api mpms chapter 19.1 (2002)

Manual of Petroleum Measurement Standards Chapter 19-Evaporative Loss

Measurement

Section 1-Evaporative Loss fromFixed-RoofTanks

THIRD EDITION, MARCH 2002

American Petroleum Institute

HelpingYou GetTheJob Done Right~M

Manual of Petroleum Measurement Standards Chapter 19-Evaporative Loss

Measurement

Section 1-Evaporative Loss fromFixed-RoofTanks

Measurement Coordination Department

THIRD EDITION, MARCH 2002


HelpingYou GetTheJob Done Right~M

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Copyright © 2002 American Petroleum Institute

FOREWORD

This standard was formerly API Publication 2518.API publications may be used by anyone desiring to do so. Every effort has been made by

the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby express1y disclaims any liability or responsibility for loss or damage resu1ting from its use or for the vio1ation of any federal, state, or municipal regu1ation with which this publication may conflict.

Suggested revisions are invited and shou1d be submitted to the standardization manager, American Petro1eum Institute, 1220 L Street, N.W., Washington, D.C. 20005.

¡¡¡

CONTENTS

19.1.1 GENERAL

Page

119.1.1.1 Scope 119.1.1.2 Referenced Publications 2

19.1.2 PROCEDURESFORCALCULATINGLOSSES 319.1.2.1 Loss Equations 319.1.2.2 Discussion ofVariables 1019.1.2.3 Summary ofCalculationProcedure 3919.1.2.4 Sample Problem 41

19.1.3 DESCRIPTION OF FlXED-ROOF TANKS 4219.1.3.1 General 4219.1.3.2 Fixed-RoofTanks 4219.1.3.3 RoofFittings 4219.1.3.4 Insulation 4419.1.3.5 Outside Surface of the Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

44

19.1.4 DETAILS OFLOSS ANALYSIS 4419.1.4.1 Introduction 4419.1.4.2 Loss Mechanisms 4519.1.4.3 Database for Loss Analysis 4719.1.4.4 Development of Standing Storage Loss Equation 4819.1.4.5 Development ofWorking Loss Equation 50

APPENDIX A DOCUMENTATION RECORDS 53

APPENDIX B METRIC UNITS 55

Figures

1 Fixed-RoofTank Geometry 12

2 Dome Roof Outage (HRO). . • • • • • • • • • • • . . • • • • • • • • • • • . • • • • • • • • • • • . . • •

•• 13

3 Vapor Pressure Function Coefficient(A) of Refined Petroleum Stocks witha Reid Vapor Pressure of 1 to 20 psi, Extrapolated to 0.1 psi 32

4 Vapor Pressure Function Coefficient(B) of Refined Petroleum Stocks with a Reid Vapor Pressure of 1 to 20 psi, Extrapolated to 0.1 psi 32

5 True Vapor Pressure (Pv) of Refined Petroleum Stocks with a ReidVaporPressure of 1 to 20 psi 33

6 Vapor Pressure Function Coefficient(A) of Crude 0i1Stocks with aReid Vapor Pressure of 2 to 15 psi, Extrapolated to 0.1 psi. . . . . . . . . . . . . . . . .. 35

7 Vapor Pressure Function Coefficient(B) of Crude Oil Stocks with aReid Vapor Pressure of 2 to 15 psi, Extrapolated to 0.1 psi. . . . . . . . . . . . . . . . .. 35

8 True Vapor Pressure (Pv) of Crude 0i1Stocks with a Reid VaporPressure of 2 to 15 psi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 36

v

VentedVapor Saturation Factor (Ks) 38

10 Working Loss Thmover Factor (KN) 39

11 Typical Fixed-RoofTank 43

Tables

1 Nomenclature 4

2 Summary of Procedures for Calculating Standing Storage Loss (Ls) . . . . . . . . . .. 6

3 Summary of Procedures for Calculating Working Loss (Lw) 8

4 Meteorological Data (TMAX,TMIN,l) for Selected U.S. Locations 14

5 Solar Absorptance (u) for Selected Tank Surfaces 19

6 Properties (M f' W vo Pv. A, B) of Selected Petroleum Liquids. . . . . . . . . . . . . .. 20

7 Properties of Selected Petrochemicals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 21

8 ASTM Distillation Slope (S) for Selected Refined Petroleum Stocks. . . . . . . . .. 34

9 Typical Concentrations of Selected Chemicals in Common Petroleum Products. 40

10 Annual Stock Tumover Rate (N) for 123 Test Tanks . . . . . . . . . . . . . . . . . . . . . .. 47

A-l Contents of Documentation Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 53

vi

Chapter 19-Evaporative Loss Measurement

Section 1-Evaporative Loss from Fixed-Roof Tanks

19.1.1 General19.1.1.1 SCOPE

This publication contains an improved method for estimat ing the total evaporative losses or the equivalent atmospheric hydrocarbon emissions from fixed-roof tanks that contain multicomponent hydrocarbon mixture stocks (such as petro leum liquid stocks like crude oils) or single-componenthydro carbon stocks (such as petrochemical stocks like ethanol). The standing storage loss equation was improved in the second edition of API Publication 2518 [also identified as API Man ual of Petroleum Measurement Standard s, Chapter 19.1 (API MPMS 19.1)] over that which appeared in the first edition of API Bulletin 2518. The working loss equation in the second edition of API Publication 2518 remained the same as that in the First Edition. This third edition utilizes the same equations as those in the second edition, but presents simplifiedcalcula tion procedures as well as additional information.

The following improvements have been incorporated into this edition:

a. Simplified forms of the emissions estimating equations for the common scenario of a low volatility liquid (i.e., true vapor pressure not greater than 0.1 psia) stored in a fixed roof tank with vents that are either open or have very low set points [i.e., not greater than 0.03 pounds (0.5 oz) per square inch].b. Methods to estimate emissions from horizontal tanks.c. Methods to account for the vent setting when estimating emissions from tanks with vent settings greater than 0.03 pounds (0.5 oz) per square inch (the previous edition accounted for the vent setting when estimating standing stor age loss, but did not account for the vent setting when estimating working loss).d. Methods to speciate estimated emissions of individual chemicals from the estimate of total hydrocarbon emissions for a multicomponent hydrocarbon mixture.

This publication was developed by the API Committee on Evaporation Loss Estimation. The equations presented are based on test-tank and field-tank data. The equations are intended to provide loss estimates for general equipment types, since it is not within the scope of this publication to address specificproprietary equipment designs.

Types of fixed-roof tanks and roof fittings currently avail able are described for information only, This publication is not intended to be used as a guide for equipment design, selection, or operation.

The equations are intended to be used to estimate average

annuallosses from uninsulated fixed-roof tanks for various

liquid stocks, stock vapor pressures, tank sizes, meteorologi cal conditions, and operating conditions. The equations are applicable to properly maintained equipment under normal working conditions. The equations were developed for non boiling stocks, although volatile liquid stocks with a true vapor pressure over 1.5 pounds per square inch absolute are not now typically stored in the U.S. in fixed-roof tanks. To calculate emissions from tanks that contain material at or aboye their boiling point or the point at which material starts to flash, the API model E&P Tank can be used. Without detailed field information, the estimation techniques become more approximate when used to calculate losses for time periods shorter than one year.

The equations are not intended to be used in the following applications:

a. To estimate losses from unstable or boiling stocks or from petroleum liquids or petrochemicals for which the vapor pres sure is not known or cannot readily be predicted.

b. To estimate losses from fixed-roof tanks which have an internal floating roof.

C. To estimate losses from fixed-rooftanks which have either roof or shell insulation.

A complete guide for estimating evaporative stock loss or the equivalent total atmospheric emissions from volatile stocks stored in fixed-roof tanks is included in 19.1.2. Detailed equations are given in 19.1.2.1, for vertical above ground tanks storing liquid stocks of low volatility at nearly atmospheric conditions. In addition, the following special cases are addressed in 19.1.2.1.4:

a. Horizontal tanks.

b. Higher volatility stocks (true vapor pressure greater than0.1 psia).

C. Higher vent settings [breather vent settings, PBP and PBv, beyond the typical range of ±O.03pounds (0.5 oz) per square inch].

A description of how to determine specific values for the variables included in the equations is given in 19.1.2.2.Refer ences are made to tables and figures that include information about the most common (typical) values to use when specific information is not available. The loss-estimation procedures are sunnnarized in 19.1.2 (Tables 2 and 3). When the proce dures in 19.1.2 are applied to a fixed-rooftank storing amulti component hydrocarbon stock, the result is an estimate of the total hydrocarbon emissions from the tank. Guidance for spe ciating total hydrocarbon emissions into the emissions of the

2 CHAPTER 19-EvAPORATIVE Loss MEASUREMENT

individual components is provided in 19.1.2.3.1. A sample problem estimating total emissions is presented in 19.1.2.4.

Typical fixed-rooftank construction is described in 19.1.3. The bases and development of the loss-estimation

proce dures presented in 19.1.2 are described in 19.1.4.The estima tion procedures were developed to provide

estimates of typical losses from fixed-roof tanks that are properly main tained and in normal working condition.

Losses from poorly maintained tanks may be greater. Because the loss equations are based on equipment

conditions that represent a large pop ulation of tanks, a loss estimate for a group of fixed-roof tanks will be more

accurate than a loss estimate for an indi vidual tank. It is difficult to determine precise values of the

loss-related parameters for any individual tank.

Equipment should not be selected for use based solely on evaporative-loss considerations. Many other factors not addressed in this publication, such as tank operation, mainte nance, and safety, are important in designing and selecting tank equipment for a given application.

19.1.1.2 REFERENCED PUBLlCATIONS

D] API, Welded Steel Tanksfor Oil Storage, Standard 650, Eighth Edition, Washington,D.C., November 1988.

[2] U.S. Department of Commerce, National Oceanic and Atmospheric Administration, "Comparative Climatic Data Through 1984," National Climatic Data Center, Asheville, North Carolina, 1986.

[3] Cinquemani, v., J.R Owenby, Jr., and RG. Baldwin, "Input for Solar Systems," Prepared by the U. S. Department of Commerce, National Oceanic and Atmospheric Adminis tration, Environmental and Information Service, National Cli matic Center, Asheville, North Carolina, Prepared for the U.S. Department of Energy, Division of Solar Technology, under Interagency Agreement No. E (49-26)-1041, Novem ber 1978 (RevisedAugust 1979).

[4] API, Evaporation Loss from Internal Floating-Roof Tanks, Publication 2519, Third Edition, Washington, D.C., June 1983.

[5] U.S. Environmental Protection Agency, "Compilation of Air Pollutant Emission Factors," USEPA Report No, AP-42, Third Edition, Section 4.3, "Storage of Organic Liquids," September 1985.

[6] The Chemical Rubber Co., Handbook of Chemistry and Physics, 51st Edition, RC. Weast, Editor, Cleveland, Ohio, pp. Dl46-Dl65, 1970.

[7] API, TechnicalData Book-Petroleum Refining, Publication 999, Ninth Revision, Washington,D.C., 1988.

[8] Perry's Chemical Engineers' Handbook, Sixth Edition, RH. Perry, D.W. Green, and J.O. Maloney, Editors, McGraw-Hill Book Co., Inc., New York, New York, 1984.

[9] API, Use of Pressure-VacuumVentValvesfor Atmospheric Pressure Tanks to Reduce Evaporation Loss, Bulletin 2521, First Edition, Washington,D.C., September 1966.

[10] API, Venting Atmospheric and Low-Pressure Storage Tanks (Nonrefrigerated and Refrigerated), Standard 2000, Third Edition, Washington,D.C., January 1982.

[11] API, Evaporation Loss from Fixed-Roof Tanks, Bulletin2518, First Edition, Washington,D.C., June 1962.

[12] Engineering-Science, Inc., "Hydrocarbon Emissions From Fixed-Roof Petroleum Tanks," Prepared for the West ero Oil and Gas Association, July 1977.

[13] Engineering-Science,Inc., "Synthetic Organic Chemical Manufacturing Industry, Emission Test Report, Breathing Loss Emissions From Fixed-Roof Petrochemical Storage Tanks," Prepared for the U.S. Environmental Protection Agency, EPA Report No. EMB-78-0CM-5, February 1979.

[14] Environmental Monitoring & Services, Inc. (subsidiary of Combustion Engineering Co.), "Breathing Loss Emissions From Fixed-Roof Tanks," Final Report, Prepared for the API, Committee on Evaporation Loss Measurement, June 1985.

[15] Beckman, Duffie and Associates, "Evaporation Loss of Petroleum From Storage Tanks," Final Report, Prepared for the API, Committee on Evaporation Loss Measurement, August 1, 1982.

[16] Knodel, B.D. and Laverman, RJ., "Data Base Generation, Analysis, and Revision of API Bulletin 2518, Task 1: Validate Computer Model," Final Report for Task 1, Prepared by CBI Industries, Inc., Prepared for the API, Committee on Evaporation Loss Measurement, Task Group 2518, Septem ber 11, 1986.

[17] Rinehart, J.K. and Laverman, RJ., "Data Base Genera tion, Analysis, and Revision of API Bulletin 2518, Task 3: Correlate Data Base," Final Report for Task 3, Prepared by CBI Industries, Inc., Prepared for the API, Committee on Evaporation Loss Measurement, Task Group 2518, August26,1988.

[18] API, "Evaporation Loss in the Petroleum Industry Causes and Control," Publication 2513, First Edition, Wash ington, D.C., February 1959.

[19] Rinehart, J.K. and Laverman, RJ., "Data Base Genera tion, Analysis and Revision of API Bulletin 2518, Task 2: Generate Computer Data Base," Final Report for Task 2, Pre pared by CBI Industries, Inc., Prepared for the API, Commit tee on Evaporation Loss Measurement, Task Group 2518, February 16, 1987.

[20] API, "Symposium on Evaporation Loss of Petroleum From Storage Tanks," Papers Presented During the 32nd Annual Meeting of the American Petroleum Institute, Held

3SECTION 1-EvAPORATIVE Loss FROM FIXED-RoOF TANKS

in Chicago, lllinois, November 10, 1952, (Also Published in API Proceedings, Vol. 32, Part I, 1952, pp. 212-281).

19.1.2 Procedures For CalculatingLosses

19.1.2.1 LOSS EQUATIONS

19.1.2.1.1 General

Procedures for estimating the total annual evaporative stock loss, or the equivalent atmospheric hydrocarbon vapor emissions, from volatile stocks stored in fixed-roof tanks, are outlined in 19.1.2. The totalloss, Ly; is the sum of the stand ing storage loss, Ls, and the working loss, Lw:

Lr (pounds per year) = Ls (pounds per year)

c. The daily average ambient temperature.

d. The daily ambient temperature range.

e. The daily total solar insulation on a horizontal surface.

f. The atmospheric pressure.

g. The molecular weight of the stock vapor.

h. The stock liquid surface temperature.

The standing storage loss, Ls, pertains to loss of stock vapors which occurs as a result of tank vapor space breathing. The standing storage loss can be estimated from Equation 2:

+ Lw(pounds per year) (1) (2)

A complete list of nomenclature, including conversion relationships, is given in Table 1. In addition, descriptions of the variables used in the calculation procedure summaries of Tables 2 and 3 are repeated in those tables. A description of how to determine specific values for the variables is given in19.1.2.2.

The following conditions are assumed in the calculation procedures presented in 19.1.2.1.2 and 19.1.2.1.3:

a. The tank is a vertical cylinder (for horizontal cylindrical tanks, see 19.1.2.1.4.1).

b. The liquid stock has a true vapor pressure not greater than0.1 psia (for higher volatility stocks, see 19.1.2.1.4.2).

c. The vents are either open or are set at approximately ±0.03 pounds (0.5 oz) per square inch (for higher vent settings, see19.1.2.1.4.3).

19.1.2.1.2 Standing Storage Loss, Ls

The following minimum information is needed to calculate the standing storage loss, Ls:

a. The tank diameter.b. The tank shell height.c. The tank roof type (cone roof or dome roof).

d. The tank outside surface color.

where KE, Hvo, Ks, and Wvare calculated from Equations 3,4,5, and 6, respectively, and the tank diameter, D, is specified by the user.

Vapor Space Expansion Factor, KE

KE = 0.04 (3a)

A more accurate estimate of KE may be obtained using Equation 3b when the solar absorptance factor (u) is known for the tank outside surface color and the average daily maxi mum and minimum ambient temperatures (TMAX and TMIN) and the daily total solar insolation (l) are known for the tank location (in order to calculate the daily vapor temperature range, I1T v. from Equation 25b).

(3b)

Vapor Space Outage, Hvo

(4)

Vented Vapor Saturation Factor, Ks

1

e. The tank location. f. The stock type.

g. The stock liquid bulk temperature.h. The stock vapor pressure (or the stock Reid vapor pressure).

i. The stock liquid level.

Ks=-------1 +0.053 PVA Hvo

Stock Vapor Density, Wv

Wv = MVPVAR TLA

(5)

(6)

Improved estimates of the standing storage loss can be obtained through a knowledge of some or all of the following additional information:

a. The tank cone roof slope or dome roof radius.b. The breather vent pressure and vacuum settings.

The constant, 365, in Equation 2 is the number of daily events in ayear, and has units of (yearr+ The constant, 0.04, in Equation 3a is dimensionless. The constant, 0.0018, in Equation 3b has units of (degrees Rankiner+, The constant,0.053, in Equation 5 has units of [(pounds per square inch absolute) feet ]-1.

Table 1-Nomenclature

Reference Information

Symbol Description Units Equations Tables Figures

A Constant in the vapor pressure equation Dimensionless 31,34 6, 7 3,6B Constant in the vapor pressure equation °R 32,35 6, 7 4, 7D Tank diameter ft 1DE Effective tank diameter, horizontal tanks ft 10HE Effective tank height, horizontal tanks ft 11HL Stock liquid height (or innage) ftHLJ( Stock maximum liquid height ftHR Tank roof height ft 17HRO Roof outage (or shell height equivalent to the volume contained under the roof) ft 16 2Hs Tank shell height ftHvo Vapor space outage (or height) ft 41 Daily total solar insulation on a horizontal surface Btu/ft2 day 4KB Vent setting correction factor Dimensionless 9, 15KE Vapor space expansion factor Dimensionless 3,14Kp Working loss product factor Dimensionless 43Ks Vented vapor saturation factor Dimensionless 5 9KN Working loss tumover factor Dimensionless 8 10L End-to-end length, horizontal tanks ftLs Standing storage loss lb/yr or bbllyr 2,12,44 2LT Totalloss lb/yr or bbllyr 1Lw Working loss lb/yr or bbllyr 7,13,46 3Mv Stock vapor molecular weight lbllb-mole 6, 7N Stock tumover rate Thmoverslyr 42PA Atmospheric pressure psiaPBP Breather vent pressure setting (always a positive value) psigPBV Breather vent vacuum setting (always a negative value) psigMB Breather vent pressure setting range psi 40PVA Stock vapor pressure at the daily average liquid surface temperature psia 29,37 6, 7 5,8PV1 pressure of the vapor space at initial (normaloperating) conditions

for pressurized servicepsig

PVN Stock vapor pressure at the daily minimum liquid surface temperature psia 30,38 6, 7 5,8Prx Stock vapor pressure at the daily maximum liquid surface temperature psia 28,36 6, 7 5,8Mv Stock daily vapor pressure range psi 39Q Stock annual net throughput (associated with increasing the stock

liquid level in the tank)bbllyr

R Ideal gas constant (l0.731) psia ft3llb-mole °RRR Tank dome roof radius ft lbRs Tank shell radius ftRVP Stock Reid vapor pressure psiS Stock ASTM-D86 distillation slope at 10 volume percent evaporated °F/vol % 33 8SR Tank cone rood slope ftlft laT5 Temperature at which 5 volume percent is evaporated °FT15 Temperature at which 15 volume percent is evaporated °FTA Ambient temperature °RTAA Daily average ambient temperature °R 20TAN Daily minimum ambient temperature °R 19TAX Daily maximum ambient temperature °R 18ATA Daily ambient temperature range °R 21TB Liquid buIk temperature °R 23TLA Daily average liquid surface temperature °R 24TLN Daily minimum liquid surface temperature °R 27TLJ( Daily maximum liquid surface temperature °R 26TMAX Daily maximum ambient temperature °F 4TMIN Daily minimum ambient temperature °F 4Tv Vapor temperature °RATv Daily vapor temperature range °R 25VLJ( Tank maximum liquid volume (or tank liquid capacity) ft3


Table 1-Nomenclature (Continued)

Reference Information

Symbol

VvDescription

Tank vapor space volnme

Units

ft

Equations

45

Tables Figures

WL Stock liquid density Ib/gal 7

Wv Stock vapor density Ib/ft3 6

Wrc Stock condensed vapor density at 60°F Ib/gal 41 6, 7

Greek Symbol Notation

a Tank surface solar absorptance DimensionJess 22 5

aR Tank roof surface solar absorptance Dimensionless 5

as Tank she1l surface solar absorptance Dimensionless 51t Constant (3.14159) DimensionJess

Fnnction Notation

Exp( ) Exponential value of the quantity in parenthesesIn ( ) NaturallogaritInn value of the quantity in parentheses

Subscript Notation

A Ambient, or atmosphericAA Ambient averageAN Ambient minimum, degrees RankineAX Ambient maximum, degrees RankineB Breather, or liquid bulkBP Breather pressureBV Breather vacuumE ExpansionL LiquidLA Liquid averageLN liquid minimumLX liquid maximumMAX Ambient maximum, degrees FahrenheitMIN Ambient minimum, degrees FahrenheitN TurnoverP ProductR RoofRO RoofoutageS Standing, or she1l, or saturationT TotalV VaporVAve

Vapor averageVapor condensed

VI initial or normal operating condition of the vapor spaceVN Vapor minimumVO Vapor outageVx Vapor maximumW Working

Unit Notation

Btu British thermal unitlb Ponnd masslb-mole Ponnd mole°R Degree Rankine°F Degree Fahrenheit

Conversion Relationships

°R = °F + 459.61psia = psig + 14.696barrels = ponnds/(42 Wvc)


Table 2-Summary of Procedures for Calculating Standing Storage Loss (Ls)

Standing Storage Loss Equation

Ls (lb/yr) = 365 KE Hvo (Jt!4) D 2 Ks Wv (2)

Variable Description Equation Units Source

KE Vapor space expansion factor Dimensionless Calculate from Equation 3a or 3b for stocks with a true vapor pressure not greater than 0.1 psia, stored in tanks with the breather vent settingrange not greater than ±0.5 oz/in2

Calculate from Equation 14 for stocks with a higher stock vapor pressure or for tanks with a higher vent setting range

=0.04 3a

=0.OO18~Tv 3b

sr, Daily vapor temperature range °R Calculate from Equation 25b

= 0.72 (TMAX- TMIN) + 0.028a 1 25b

TMAX Daily maximum ambient temperature °F User specified or Table 4

TMIN Daily minimum ambient temperature °F User specified or Table 4

a Tank surface solar absorptance Dimensionless User specified or Table 5Calculate from Equation 22 for different color roof and shell

1 Daily total solar insolation on a hori- Btu/fté day User specified or Table 4 zontal surface

Hvo Vapor space outage ft Calculate from Equation 4

=Hs-HL+HRO 4

Hs Tank shell height ft User specified (Figure 1)

HL Stock liquid height (or innage) ft User specified (Figure 1)

HRO Roofoutage ft Calculate from Equation l6a for a cone roofCalculate from Equation l6b for a dome roof

= (1/3)HR l6a

= HR [(1/2) + (1/6)(HRi'Rs)2] l6b

HR Tank roof height ft User specified (Figure 1), or Equation 17a for a cone roof Equation l7b for dome roof

=SRRs l7a

=RR - (RR 2 _Rs2)O.5 l7b

SR Tank cone roof slope ftlft User specified (Figure 1)


Table 2-Summary of Procedures for Calculating Standing Storage Loss (Ls) (Continued)

Standing Storage Loss Equation

Ls (lb/yr) = 365 KE Hvo (Jt!4)D 2 Ks Wv (2)


Rs

D

Ks

PVA

A

B

Tank shell radius Tank

dome roof radius Tank

diameter

Vented vapor saturation factor

K s = -:----:::--c::-=--=-----::-::--1 +0.053 PVA Hvo

Stock vapor pressure at the daily average liquid surface temperature

= exp[A - (B/TLA)]

Constant in the 2-constant vapor pressure equation

Constant in the 2-constant vapor pressure equation

Daily average liquid surface temperature

= TAA + 0.56(6 a - 1) + 0.0079 al

Daily average ambient temperature

5

29

24b

ft User specified (Figure 1)

ft User specified (Figure 1)

ft User specified

Dimensionless Calculate from Equation 5

psia Calculate from Equation 29 orFigure 5 for refined petroleum stocksFigure 8 for crude oil stocks

Dimensionless Table 6 for selected petroleum liquid stocksTable 7 for selected petrochemical stocksEquation 31 or Figure 3 for refined petroleum stocksEquation 34 or Figure 6 for crude oil stocks

Table 6 for selected petroleum liquid stocksTable 7 for selected petrochemical stocksEquation 32 or Figure 4 for refined petroleum stocksEquation 35 or Figure 7 for crude oil stocks

Calculate from Equation 24b

User specified or Table 4 and Equations 18 - 20

Wv Stock vapor density

MVPVA=---R TLA

R Ideal gas constant (10.731)

Mv Stock vapor molecular weight

Ib/ft3 Calculate from Equation 6

6

psia ft3

lb-mole °R

lb/lb-mole User specified orTable 6 for selected petroleum liquid stocksTable 7 for selected petrochemical stocks64 for gasoline50 for U.S. mid-continent crude oil stocks

Table 3-Summary of Procedures for CalculatingWorking Loss (Lw)

Working Loss Equations

Lw(lb/yr) =N HLX(Jt/4) D2 KNKpKE Wv (7)


N Stock turnover rate turnover/yr User specified orCalculate from Equation 42

= 5.614 Q 2(:n:/4) D HLX

(42)

Q D

H

LX

= Stock annual net throughput

Tank diameter

Stock maximum liquid height

Working loss turnover factor

bbl/yr

ft

ft

Dimensionless

User specified

User specified

User specified

Calculate from Equation 8a or 8b= 1 (for N~36) (8a)

(180+N) (forN >36)6N

(8b)

Kp Working loss product factor Dimensionless 0.75 for crude oil stocks1.0 for refined petroleum stocks1.0 for single-componentpetrochemical stocks

Vent setting correction factor Dimensionless Calculate from Equation 9 for breather vent settingpressure range, ME , not greater than ±O.5oz/in2Calculate from Equation 15 for higher vent settings

= 1.0 9

Wv Stock vapor density lb/ft3 Calculate from Equation 6= (MVPVA) / (R TLA) 6

M v Stock vapor molecular weight lb/lb-mole User specified orTable 6 for selected petroleum liquid stocksTable 7 for selected petrochemical stocks64 for gasoline50 for U.S. midcontinent crude oil stocks

P VA Stock vapor pressure at the daily average psia Calculate from Equation 29 orliquid surface temperature Figure 5 for refined petroleum stocks

Figure 8 for crude oil stocks= exp [A - (B/TLA)] (29)

A Constant in the 2-constant vapor pressure Dimensionless Table 6 for selected petroleum liquid stocksequation Table 7 for selected petrochemical stocks

Equation 31 or Figure 3 for refined petroleum stocksEquation 34 or Figure 6 for crude oil stocks

B Constant in the 2-constant vapor pressure °R Table 6 for selected petroleum liquid stocksequation Table 7 for selected petrochemical stocks

Equation 32 or Figure 4 for refined petroleum stocksEquation 35 or Figure 7 for crude oil stocks

R ideal gas constant (10.731) psia ft3/lb-mole °R

TLA Daily average liquid surface temperature Calculate from Equation 24b= TAA + 0.56(6a - 1) + 0.OO79a1 24b

TAA Daily average ambient temperature °R User specified orTable 4 and Equations 18 through 20

a Tank surface solar absorptance Dimensionless User specified or Table 5Calculate from Equation 22 for different color roofandshell

1 Daily total solar insolation on a horizon Btu/ft2 day User specified or Table 4tal surface

n/

The procedures used to calculate the standing storage loss are summarized in Table 2.

19.1.2.1.3 Working Loss, Lw

The working loss, Lw; can be calculated from the following information:

a. The stock vapor molecular weight.

b. The stock vapor pressure (or the stock Reid vapor pressure).

c. The tank diameter and stock maximum liquid height or the stock annual net throughput (associated with increasing the stock liquid level).

d. The stock turnover rateo

e. The stock type.

Improved estimates of the working loss can be obtained through a knowledge of some or all of the following addi tional information:

a. The breather vent pressure settings.

b. The stock liquid surface temperature.

The working loss, Lw; pertains to loss of stock vapors which occurs as a result of tank emptying and filling opera tions. The working loss can be estimated from Equation 7:

(7)

If the annual net throughput, Q, is known, the terms N, HL){, and (n/4) D2 can be replaced by the following equiva lence:

where the constant, 5.614, has units of cubic feet per barrel.The working los s turnover factor, KN, is calculated from

Equation 8a when the stock turnover rate, N, does not exceed36 tank tumovers per year, and from Equation 8b when the tank tumovers exceed 36 per year.

(for N :;;36) (8a)

KN = (180 + N)/(6N) (for N~36) (8b)

The vent setting correction factor, KB, is equal to 1 for abreather vent setting range, MB, not greater than the typical range of ±0.03 pounds (0.5 oz) per square inch.

The procedures used to calculate the working loss are summarized in Table 3.

19.1.2.1.4 Special Cases

19.1.2.1.4.1 Horizontal Tanks

If a user needs to estimate emissions from a horizontal fixed- roof tank, the length and diameter of the horizontal tank may be transformed to the diameter and height of an equiva lent vertical tank. First, assume that the horizontal tank is a cylinder (i.e., that the cross section at its middle extends all the way to each of its ends). Then, by assuming the horizontal tank to be one-half full, the surface of the liquid in the tank describes a rectangle, having a length equal to the length of the tank and a width equal to the cross-sectional diameter of the tank. This liquid-surface rectangle of the horizontal tank may be converted to a circle of equal area to describe an equivalent vertical tank. The diameter, DE, of the equivalent vertical tank is calculated from Equation 10.

D = JLD (10)E

where

L = length of the horizontal tank (for tanks with rounded ends, use the overalllength), and

D = diameter of a vertical cross-section of the horizontal tank.

The height, HE, of the equivalent vertical tank is deter mined by calculating the height of the vertical tank that will result in an enclosed volume approximately equal to that of the horizontal tank. By assuming the volume of the horizontal tank to be equal to the cross-sectional area of the tank times the length of the tank, the height, HE, of an equivalent vertical tank may be calculated from Equation 11.

HE= (n/4) D (11)

The standing storage loss of the horizontal tank may becalculated by substituting DE for D and (HE/2) for Hvo inEquation 2, as shown in Equation 12.

(12)

Altematively, the standing storage loss of the horizontaltank may be calculated without first determining DE andHE, if the head space volume of the horizontal tank is known. Equation 12 would be modified by substituting the

KB=l (9) head space volume, expressed in cubic feet, for the term,

[(HE/2) (n/4 DE2)], and the standing storage loss could then be calculated.

For underground horizontal tanks, assume that no standing storage losses occur (Ls = O) because the insulating nature ofthe earth limits the diurnal temperature change.

The working loss of the horizontal tank may be estimated by substituting DE in place of D, and HE in place of HL){, in Equation 7. This modified form of Equation 7 is shown in Equation 13.

(13)

sion is less than or equal to 1), use the value of 1 for KB fromEquation 9.

When:

Then:

(15)

Altematively, the working loss of the horizontal tank may be calculated without first determining DE and HE, if theannual net throughput, Q, of the horizontal tank is known.Given the annual net throughput, the working loss may be calculated from Equation 7 by replacing the N, HL){, and (n/4)

where

KN = working loss turnover (saturation) factor(dimensionless ),

D2 terms with the equivalent term, 5.614 Q.

19.1.2.1.4.2 HigherVolatility Stocks

When the liquid stock has a true vapor pressure greater than 0.1 psia, a more accurate estimate of the vapor space expansion factor, KE, should be calculated from Equation 14.

(14)

where the stock daily vapor pressure range, Mv. may be calculated from Equation 39a or 39b.

The standing storage loss of the tank storing the higher vol atility stock would then be calculated from Equation 2 using the value of KE determined from Equation 14. When the cal culation of Equation 14 yields a negative value for KE, use zero as the value of KE•This will result in an estimated stand ing storage los s of zero, on the basis that the vent pressure set ting range, MB, is sufficiently high to prevent breathing losses from occurring during the average conditions assumed.

The working loss of the tank storing the higher volatility stock would be calculated from Equation 7 without any modification.

19.1.2.1.4.3 HigherVent Settings

When the breather vent settings are significantly higher than the typical range of plus and minus one-half ounce per square inch, a more accurate estimate of the vapor space expansion factor, KE, may be calculated from Equation 14. Higher vent settings may also warrant the use of a value less than 1 for the vent setting correction factor, KB, as determined from Equation 15.

When the following condition is met, then a vent setting correction factor, KB, may be determined using Equation 15. When this condition is not met (i.e., the value of the expres-

PBP = breather vent pressure setting, in pounds persquare inch gauge,

PA = atmospheric pressure, in pounds per square inch absolute,

PV1 = pressure of the vapor space at initial (normal operating) conditions, in pounds per square inchgauge,

KB = vent setting correction factor (dimensionless),

PVA = stock vapor pressure at the daily average liquid surface temperature, in pounds per square inch absolute.

The standing storage loss of the tank with the higher vent settings is calculated from Equation 2 using the value of KE determined from Equation 14. When the calculation of Equa tion 14 yields a negative value for KE, use zero as the value of KE as explained in 19.1.2.1.4.2.

The working loss of the tank with the higher vent settings is calculated from Equation 7 using the value of KB deter mined from Equation 15, if the given condition is met, to account for any reduction in emissions due to condensation of vapors prior to the opening of the vent.

19.1.2.2 DISCUSSION OFVARIABLES

19.1.2.2.1 General

Information is sunnnarized in 19.1.2.2.2 and 19.1.2.2.3 on how to determine specific values for the variables in the loss equations given in 19.1.2.1. Tables, graphs, and the range of values of the variables for which the loss equations are appli cable are cited for reference.

To obtain the most accurate estimate, detailed information pertinent to the specific tank or tanks under consideration should be used. The typical values included in 19.1.2.2 and

SECTION 1-EvAPORATIVE Loss FROM FIXED-RoOF TANKS 11

the cited tables and figures should be used only when actual detailed information is not available.

More detailed discussion of the definition, development and effects of the variables is given in 19.1.4.

19.1.2.2.2 Standing Storage Loss Variables

The standing storage loss, Ls, is related in Equation 2 to the following variables:

a. Tank vapor space volume, Vv(expressed in terms of HvoandD).

b. Stock vapor density, Wv.c. Vapor space expansion factor, KE•

d. Vented vapor saturation factor, Ks.

where

HRO = roof outage (or additional shell height equivalent to the volume contained under the roof), in feet,

HR = tank roof height, in feet,

SR = tank cone roof slope, in feet per foot,

Rs = tank shell radius, in feet.

If the tank cone roof slope, SR, is not known, a typical value of 0.0625 feet per foot may be assumed.

19.1.2.2.2.1.2 Dome Roof

For a dome roof, the roof outage (or additional shell height equivalent to the volume contained under the roof), HRO, may be determined from Figure 2 or calculated from Equation 16b:

These variables can be calculated using Equations 3 through 6. Data sources and proper usage for each ofthe vari ables in Equations 3 through 6 are described in 19.1.2.2.2.1 through 19.1.2.2.2.13.

19.1.2.2.2.1 Vapor Space Outage, Hvo

The vapor space outage, Hvo, is the height of a cylinder of

where

where

(16b)

(17b)

tank diameter, D, whose volume is equivalent to the vapor space volume of a fixed-roof tank, including the volume under the cone or dome roof. Figure 1 illustrates the geometry of a fixed-roof tank with either a cone roof or dome roof. The vapor space outage may be determined from Equation 4:

(4)

where

Hvo = vapor space outage, in feet,

Hs = tank shell height, in feet,

HL = stock liquid height, in feet,

HRO = roof outage (or additional shell height equivalent to the volume contained under the roof), in feet.

19.1.2.2.2.1.1 Cone Roof

For a cone roof, the roof outage (or additional shell height equivalent to the volume contained under the roof), HRO, can be calculated from Equation 16a:

(16a)

where

(17a)

HRO = roof outage (or additional shell height equivalentto the volume contained under the roof), in feet,

HR = tank roof height, in feet,

Rs = tank shell radius, in feet,

RR = tank dome roof radius, in feet.

Figure 2 shows for a dome roof that the ratio HRO.HR var ies from 0.500 to 0.666. This may be compared to the same ratio for a cone roof which, from Equation 16a, is a constant value ofO.333.

Section 3.10.6 of API Standard 650 [1] indicates that the tank dome roof radius, RR, varies between a minimum of 0.8D and a maximum of 1.2 D. If the tank dome roof radius is not known, a typical value of 1.0 D may be assumed. In this case, Equations 16b and 17b simplify to Equations 16c and 17c:

HRO = 0.137 Rs (16c)

HR = 0.268 Rs (17c)

19.1.2.2.2.2 Meteorological Data, TMAX, TM1N> I

The meteorological data needed to estimate the standing storage loss, Ls, consists of:

a. Daily maximum ambient temperature, TMAX.

b. Daily minimum ambient temperature, TM/N;

c. Daily total solar insolation on a horizontal surface, l.


Cane roaf slape, SR

-- --------

l. o :1Con e Roof

l. o :1Dome Roof

Figure 1-Fixed-RoofTank Geometry


Equations 20 and 21, respectively:

(20)

(21)

where

TAA = daily average ambient temperature, in degreesRankine,

TAX = daily maximum ambient temperature, in degrees Rankine,

TAN = daily minimum ambient temperature, in degrees Rankine,

I1TA = daily ambient temperature range, in degreesRankine.

Figure 2-Dome Roof Outage (HRO)

The term insolation refers to incident-solar-radiation.When possible, meteorological data for the tank site should

be used. If this data is not available, meteorological data from the nearest local weather station may be used. Data for selected U.S. locations are listed in Table 4.

Data for other U.S. locations may be found in weather station records [2,3].

The daily maximum and minimum ambient temperatures are reported in degrees Fahrenheit, but must be con verted to degrees Rankine from Equations 18 and 19, respectively:

TAX= TMAX+ 459.67 (18)

19.1.2.2.2.3 Tank Paint Solar Absorptance, a

The tank outside surface solar absorptance, a, is a function of the tank surface color, surface shade or type, and surface condition. Table 5 lists the solar absorptance for selected tank surfaces. Section E of the Documentation File contains addi tional solar absorptance values for a variety of paint colors.

If specific information is not available on the tank surface color and surface condition, a white shell and roof, with the paint in good condition, can be assumed to represent the most common or typical tank surface in use.

If the tank roof and shell are painted a different color, Equation 22 may be used to determine the tank surface solar absorptance, a.

aR+aS

TAN = TM/N+459.67 (19)where

0.= --2

(22)

where

TAX = daily maximum ambient temperature, in degrees Rankine,

a = tank surface solar absorptance (dimensionless),

aR = tank roof surface solar absorptance (dimensionless),

TMAX = daily maximum ambient temperature, in degrees Fahrenheit,

TAN = daily minimum ambient temperature, in degrees Rankine,

TM/N = daily minimum ambient temperature, in degrees Fahrenheit.

The daily average ambient temperature, TAA, and the daily ambient temperature range, I1TA, may be calculated from

as = tank shell surface solar absorptance (dimensionless).

19.1.2.2.2.4 Liquid BulkTemperature, Ts

The liquid bulk temperature, TE, is the average temperature of the liquid stock in the storage tank. This information is usually available from tank gaging records or other tank oper ating records. The liquid bulk temperature is used to estimate the daily average liquid surface temperature, TLA (see19.1.2.2.2.5).

Table 4-Meteorological Data (T MAX, TM/N. 1) for Selected U.S. Locations

Location

Property Monthly Averages------------- ----------------------------------------------------------Annu~

Symbol Units Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct Nov. Dec. Average

BirminghamAirport,AL TMAX °F 52.1 57.3 65.2 15.2 81.6 87.9 90.3 89.7 84.6 74.8 63.7 55.9 73.2TMIN °F 33.0 35.2 42.1 50.4 58.3 65.9 69.8 69.1 63.6 50.4 40.5 35.2 51.1

1 Btu/ft2 day 707 967 1296 1674 1857 1919 1810 1724 1455 1211 858 661 1345

Montgomery,AL TMAX °F 57.0 60.9 68.1 77.0 83.6 89.8 91.5 91.2 86.9 77.5 67.0 59.8 75.9TMIN °F 36.4 38.8 45.5 53.3 61.1 68.4 71.8 71.1 66.4 53.1 43.0 37.9 53.9

1 Btu/ft- day 752 1013 1341 1729 1897 1972 1841 1746 1468 1262 915 719 1388

Homer,AK TMAX °F 27.0 31.2 34.4 42.1 49.8 56.3 60.5 60.3 54.8 44.0 34.9 27.7 43.6TMIN °F 14.4 17.4 19.3 28.1 34.6 41.2 45.1 45.2 39.7 30.6 22.8 15.8 29.5

1 Btu/ft2 day 122 334 759 1248 1583 1751 1598 1189 791 437 175 64 838

Phoenix,AZ TMAX °F 65.2 69.7 74.5 83.1 92.4 102.3 105.0 102.3 98.2 87.7 14.3 66.4 85.1TMIN °F 39.4 42.5 46.7 53.0 61.5 70.6 79.5 77.5 70.9 59.1 46.9 40.2 57.3

1 Btu/ft2 day 1021 1374 1814 2355 2677 2739 2487 2293 2015 1577 1151 932 1869

Tucson,AZ TMAX °F 64.1 67.4 71.8 80.1 88.8 98.5 98.5 95.9 93.5 84.1 72.2 65.0 81.7TMIN °F 38.1 40.0 43.8 49.7 57.5 61.4 73.8 72.0 61.3 56.7 45.2 39.0 54.2

1 Btu/ft2 day 1099 1432 1864 2363 2671 2730 2341 2183 1979 1602 1208 996 1872

Fort Smith, AR TMAX °F 48.4 53.8 62.5 73.7 81.0 88.5 93.6 92.9 85.7 75.9 61.9 52.1 72.5TMIN °F 26.6 30.9 38.5 49.1 58.2 66.3 70.5 68.9 62.1 49.0 37.7 30.2 49.0

1 Btu/ft2 day 744 999 1312 1616 1912 2089 2065 1877 1502 1201 851 682 1404

Little Rock, AR TMAX °F 49.8 54.5 63.2 73.8 81.7 89.5 92.7 92.3 85.6 75.8 62.4 53.2 72.9TMIN °F 29.9 33.4 41.2 50.9 59.2 67.5 71.4 69.6 63.0 50.4 40.0 33.2 50.8

1 Btu/ft2 day 731 1003 1313 1611 1929 2107 2032 1861 1518 1228 847 674 1404

Bakersfield,CA TMAX °F 57.4 63.7 68.6 75.1 83.9 92.2 98.8 94.4 90.8 81.0 67.4 57.6 77.7TMIN °F 38.9 42.6 45.5 50.1 57.2 64.3 70.1 68.5 63.8 54.9 44.9 38.7 53.3

1 Btu/ft2 day 766 1102 1595 2095 2509 2749 2684 2421 1992 1458 942 677 1749

Long Beach, CA TMAX °F 66.0 67.3 68.0 70.9 73.4 77.4 83.0 83.8 82.5 78.4 72.7 67.4 74.2TMIN °F 44.3 45.9 47.7 50.8 55.2 58.9 62.6 64.0 61.6 56.6 49.6 44.7 53.5

1 Btu/ft2 day 928 1215 1610 1938 2065 2140 2300 2100 1701 1326 1004 847 1598

Los Angeles Airport, CA TMAX °F 64.6 65.5 65.1 66.7 69.1 72.0 75.3 76.5 76.4 74.0 70.3 66.1 70.1TMIN °F 41.3 48.6 49.1 52.2 55.7 59.1 62.6 64.0 62.5 58.5 52.1 47.8 55.0

1 Btu/ft2 day 926 1214 1619 1951 2060 2119 2308 2080 1681 1317 1004 849 1594

Sacramento, CA TMAX °F 52.6 59.4 64.1 71.0 19.1 87.4 93.3 91.7 87.6 11.7 63.2 53.2 73.4TMIN °F 37.9 41.2 42.4 45.3 50.1 55.1 57.9 51.6 55.8 50.0 42.8 37.9 47.8

1 Btu/ft2 day 597 939 1458 2004 2435 2684 2688 2368 1907 1315 782 538 1643

San Francisco Airport, TMAX °F 55.5 59.0 60.6 63.0 66.3 69.6 71.0 71.8 73.4 70.0 62.7 56.3 64.9CA

TMIN °F 41.5 44.1 44.9 46.6 49.3 52.0 53.3 54.2 54.3 51.2 46.3 42.2 48.31 Btu/ft2 day 708 1009 1455 1920 2226 2317 2392 2117 1742 1226 821 642 1553

Table 4-Meteorological Data (T MAX, TM/N. 1) for Selected U.S. Locations (Continued)

Loeation


Symbol Units Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oet Nov. Dee. Average

Santa Maria, CA TMAX °F 62.8 64.2 63.9 65.6 67.3 69.9 72.1 72.8 74.2 73.3 68.9 64.6 68.3TMIN °F 38.8 40.3 40.9 42.7 46.2 49.6 52.4 53.2 51.8 47.6 42.1 38.3 45.3

1 Btu/ft2 day 854 1141 1582 1921 2141 2349 2341 2106 1730 1353 974 804 1608

Denver,CO TMAX °F 43.1 46.9 51.2 61.0 70.7 81.6 88.0 85.8 77.5 66.8 52.4 46.1 64.3TMIN °F 15.9 20.2 24.7 33.7 43.6 52.4 58.7 57.0 47.7 36.9 25.1 18.9 36.2

1 Btu/ft2 day 840 1127 1530 1879 2135 2351 2273 2044 1727 1301 884 732 1568

Grand Junction, CO TMAX °F 35.7 44.5 54.1 65.2 76.2 87.9 94.0 90.3 81.9 68.7 51.0 38.7 65.7TMIN °F 15.2 22.4 29.7 38.2 48.0 56.6 63.8 61.5 52.2 41.1 28.2 17.9 39.6

1 Btu/ft2 day 791 1119 1554 1986 2380 2599 2465 2182 1834 1345 918 731 1659

Wilmington, DE 39.2 41.8 50.9 63.0 72.7 81.2 85.6 84.1 77.8 66.7 54.8 43.6 63.5TMIN °F 23.2 24.6 32.6 41.8 51.7 61.2 66.3 65.4 58.0 45.9 36.4 27.3 44.5

1 Btu/ft-day 571 827 1149 1480 1710 1883 1823 1615 1318 984 645 489 1208

Atlanta,GA TMAX °F 51.2 55.3 63.2 73.2 79.8 85.6 87.9 87.6 82.3 72.9 62.6 54.1 71.3TMIN °F 32.6 34.5 41.7 50.4 58.7 65.9 69.2 68.7 63.6 51.4 41.3 34.8 51.1

1 Btu/ft2 day 718 969 1304 1686 1854 1914 1812 1709 1422 1200 883 674 1345

Savannah,GA TMAX °F 60.3 63.1 69.9 77.8 84.2 88.6 90.8 90.1 85.6 77.8 69.5 62.5 76.7TMIN °F 37.9 40.0 46.8 54.1 62.3 68.5 71.5 71.4 67.6 55.9 45.5 39.4 55.1

1 Btu/ft2 day 795 1044 1399 1761 1852 1844 1784 1621 1364 1217 941 754 1365

Honolulu, ID TMAX °F 79.9 80.4 81.4 82.7 84.8 86.2 87.1 88.3 88.2 86.7 83.9 81.4 84.2TMIN °F 65.3 65.3 67.3 68.7 70.2 71.9 73.1 73.6 72.9 72.2 69.2 66.5 69.7

1 Btu/ft2 day 1180 1396 1622 1796 1949 2004 2002 1967 1810 1540 1266 1133 1639

Chieago,IL TMAX °F 29.2 33.9 44.3 58.8 70.0 79.4 83.3 82.1 75.5 64.1 48.2 35.0 58.7TMIN °F 13.6 18.1 27.6 38.8 48.1 57.7 62.7 61.7 53.9 42.9 31.4 20.3 39.7

1 Btu/ft2 day 507 760 1107 1459 1789 2007 1944 1719 1354 969 566 402 1215

Springfield,IL TMAX °F 32.8 38.0 48.9 64.0 74.6 84.1 87.1 84.7 79.3 67.5 51.2 38.4 62.6TMIN °F 16.3 20.9 30.3 42.6 52.5 62.0 65.9 63.7 55.8 44.4 32.9 23.0 42.5

1 Btu/ft2 day 585 861 1143 1515 1866 2097 2058 1806 1454 1068 677 490 1302

Indianapolis, IN TMAX °F 34.2 38.5 49.3 63.1 73.4 82.3 85.2 83.7 77.9 66.1 50.8 39.2 62.0TMIN °F 17.8 21.1 30.7 41.7 51.5 60.9 64.9 62.7 55.3 43.4 32.8 23.7 42.2

1 Btu/ft2 day 496 747 1037 1398 1638 1868 1806 1644 1324 977 579 417 1165

Wiehita,KS TMAX °F 39.8 46.1 55.8 68.1 77.1 87.4 92.9 91.5 82.0 71.2 55.1 44.6 67.6TMIN °F 19.4 24.1 32.4 44.5 54.6 64.7 69.8 67.9 59.2 46.9 33.5 24.2 45.1

1 Btu/ft2 day 704 1058 1406 1783 2036 2264 2239 2032 1616 1250 871 690 1502

Louisville, KY TMAX °F 40.8 45.0 54.9 67.5 76.2 84.0 87.6 86.7 80.6 69.2 55.5 45.4 66.1TMIN °F 24.1 26.8 35.2 45.6 54.6 63.3 67.5 66.1 59.1 46.2 36.6 28.9 46.2

1 Btu/ft2 day 546 789 1102 1467 1720 1904 1838 1680 1361 1042 653 488 1216

Baton Rouge, LA TMAX °F 61.1 64.5 71.6 79.2 85.2 90.6 91.4 90.8 87.4 80.1 70.1 63.8 78.0TMIN °F 40.5 42.7 49.4 57.5 64.3 70.0 72.8 72.0 68.3 56.3 47.2 42.3 57.0

1 Btu/ft2 day 785 1054 1379 1681 lX71 1926 1746 1677 1464 1301 920 737 1379


Location



Lake Charles, LA TMAX °F 60.8 64.0 70.5 77.8 84.1 89.4 91.0 90.8 87.5 80.8 70.5 64.0 77.6TMIN °F 42.2 44.5 50.8 58.9 65.6 71.4 73.5 72.8 68.9 57.7 48.9 43.8 58.3

1 Btu/ft2 day 728 1010 1313 1570 lX49 1970 1788 1657 1485 1381 917 706 1365

New Orleans, LA TMAX °F 61.8 64.6 71.2 78.6 84.5 89.5 90.7 90.2 86.8 79.4 70.1 64.4 77.7TMIN °F 43.0 44.8 51.6 58.8 65.3 70.9 73.5 73.1 70.1 59.0 49.9 44.8 58.7

1 Btu/ft2 day 83.5 1112 1415 1780 1968 2004 1814 1717 1514 1335 973 779 1437

Detroit, MI TMAX °F 30.6 33.5 43.4 57.7 69.4 79.0 83.1 X1.5 74.4 62.5 47.6 35.4 58.2TMIN °F 16.1 18.0 26.5 36.9 46.7 56.3 60.7 59.4 52.2 41.2 31.4 21.6 38.9

1 Btu/ft2 day 417 680 1000 1399 1716 1866 1835 1576 1253 876 478 344 1120

Grand Rapids, MI TMAX °F 29.0 31.7 41.6 56.9 69.4 78.9 83.0 81.1 73.4 61.4 46.0 33.8 57.2TMIN °F 14.9 15.6 24.5 35.6 45.5 55.3 59.8 58.1 50.8 40.4 30.9 20.7 37.7

1 Btu/ft2 day 370 648 1014 1412 1755 1957 1914 1676 1262 858 446 311 1135

Minneapolis-St. Paul, MN

19.9 26.4 37.5 56.0 69.4 78.5 83.4 80.9 71.0 59.7 41.1 26.7 54.2

TMIN °F 2.4 8.5 20.8 36.0 47.6 57.7 62.7 60.3 50.2 39.4 25.3 11.7 35.21 Btu/ft2 day 464 764 1104 1442 1737 1928 1970 1687 1255 860 480 353 1170

Jackson,MS TMAX °F 56.5 60.9 68.4 77.3 84.1 90.5 92.5 92.1 87.6 78.6 67.5 60.0 76.3TMIN °F 34.9 37.2 44.2 52.9 60.8 67.9 71.3 70.2 65.1 51.4 42.3 37.1 52.9

1 Btu/ft2 day 754 1026 1369 1708 1941 2024 1909 1781 1509 1271 902 709 1409

Billings, MT TMAX °F 29.9 37.9 44.0 55.9 66.4 76.3 86.6 84.3 72.3 61.0 44.4 36.0 57.9TMIN °F 11.8 18.8 23.6 33.2 43.3 51.6 58.0 56.2 46.5 37.5 25.5 18.2 35.4

1 Btu/ft2 day 486 763 1190 1526 1913 2174 2384 2022 1470 9X7 561 421 1325

Las Vegas, NV TMAX °F 56.0 62.4 68.3 77.2 87.4 98.6 104.5 101.9 94.7 X1.5 66.0 57.1 79.6TMIN °F 33.0 37.7 42.3 49.8 59.0 68.6 75.9 73.9 65.6 53.5 41.2 33.6 52.8

1 Btu/ft2 day 978 1340 1824 2319 2646 2778 2588 2355 2037 1540 1086 881 1864

Newark,NJ TMAX °F 38.2 40.3 49.1 61.3 71.6 80.6 85.6 84.0 76.9 66.0 54.0 42.3 62.5TMIN °F 24.2 25.3 33.3 42.9 53.0 62.4 67.9 67.0 59.4 48.3 39.0 28.6 45.9

1 Btu/ft2 day 552 793 1109 1449 1687 1795 1760 1565 1273 951 596 454 1165

Roswell,NM TMAX °F 55.4 60.4 67.7 76.9 85.0 93.1 93.7 91.3 84.9 75.8 63.1 56.7 75.3TMIN °F 27.4 31.4 37.9 46.8 55.6 64.8 69.0 67.0 59.6 47.5 35.0 28.2 47.5

1 Btu/ft2 day 1047 1373 1807 2218 2459 2610 2441 2242 1913 1527 1131 952 1810

Buff~o,NY TMAX °F 30.0 31.4 40.4 54.4 65.9 75.6 80.2 78.2 71.7 60.2 47.0 65.0 55.8TMIN °F 17.0 17.5 25.6 36.3 46.3 56.4 61.2 59.3 52.7 47.2 33.6 22.5 39.3

1 Btu/ft2 day 349 546 XX9 1315 1597 1804 1776 1513 1152 7X4 403 283 1034

NewYork,NY TMAX °F 37.4 39.2 47.3 59.6 69.7 78.7 83.9 82.3 75.2 64.2 52.9 41.5 61.0(LaGuardiaAirport)

TMIN °F 26.1 27.3 34.6 44.2 53.7 63.2 68.9 68.2 61.2 50.5 41.2 30.8 47.51 Btu/ft2 day 548 795 1118 1457 1690 1802 1784 1583 1280 951 593 457 1171


Loeation

Property MonthlyAverages------------- ----------------------------------------------------------Annu~

Symbol Units Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oet Nov. Dee. Average

Cleveland,OH °F 32.5 34.8 44.8 57.9 68.5 78.0 81.7 80.3 74.2 62.7 49.3 37.5 58.5

TMIN °F 18.5 19.9 28.4 38.3 47.9 57.2 61.4 60.5 54.0 43.6 34.3 24.6 40.71 Btu/ft2 day 388 601 922 1350 1681 1843 1828 1583 1240 867 466 318 1091

Columbus,OH TMAX °F 34.7 38.1 49.3 62.3 72.6 81.3 84.4 83.0 76.9 65.0 50.1 39.4 61.5TMIN °F 19.4 21.5 30.6 40.5 50.2 59.0 63.2 61.7 54.6 42.8 33.5 24.7 41.8

1 Btu/ft2 day 459 677 980 1353 1647 1813 1755 1641 1282 945 538 387 1123

Toledo,OH TMAX °F 30.7 34.0 44.6 59.1 70.5 79.9 a3.4 81.8 75.1 63.3 47.9 35.5 58.8TMIN °F 15.5 17.5 26.1 36.5 46.6 56.0 60.2 58.4 51.2 40.1 30.6 20.6 38.3

1 Btu/ft2 day 435 680 991 1384 1717 1878 1849 1616 1276 911 498 355 1133

Oldahoma,City,OK 46.6 52.2 61.0 71.7 79.0 87.6 93.5 92.8 84.7 74.3 59.9 50.7 71.2TMIN °F 25.2 29.4 37.1 48.6 57.7 66.3 70.6 69.4 61.9 50.2 38.6 29.1 48.6

1 Btu/ft2 day 801 1055 1400 1725 1918 2144 2128 1950 1554 1233 901 725 1461

Tulsa,OK TMAX °F 45.6 51.9 60.8 72.4 79.7 87.9 93.9 93.0 85.0 74.9 60.2 50.3 71.3TMIN °F 24.8 29.5 31.7 49.5 58.5 67.5 72.4 70.3 62.5 50.3 37.1 29.3 49.2

1 Btu/ft2 day 732 978 1306 1603 1822 2021 2031 1865 1473 1164 827 659 1373

Astoria,OR TMAX °F 46.8 50.6 51.9 55.5 60.2 63.9 67.9 68.6 67.8 61.4 53.5 48.8 58.1TMIN °F 35.4 37.1 36.9 39.7 44.1 49.2 52.2 52.6 49.2 44.3 39.7 37.3 43.1

1 Btu/ft2 day 315 545 866 1253 1608 1656 1746 1499 1183 713 387 261 1000

Portland,OR TMAX °F 44.3 50.4 54.5 60.2 66.9 72.7 79.5 78.6 74.2 63.9 52.3 46.4 62.0

TMIN °F 33.5 36.0 37.4 40.6 46.4 52.2 55.8 55.8 51.1 44.6 38.6 35.4 44.01 Btu/ft2 day 310 554 895 1308 1663 1773 2031 1674 1217 124 388 260 1067

Philadelphia,PA TMAX °F 38.6 41.1 50.5 63.2 73.0 81.7 86.1 84.6 77.8 66.5 54.5 43.0 63.4TMIN °F 23.8 25.0 33.1 42.6 52.5 61.5 66.8 66.0 58.6 46.5 37.1 28.0 45.1

1 Btu/ft2 day 555 795 1108 1434 1660 1811 1758 1575 1281 959 619 470 1169

Pittsburgh,PA TMAX °F 34.1 36.8 47.6 60.7 70.8 79.1 82.7 81.1 74.8 62.9 49.8 38.4 59.9TMIN °F 19.2 20.7 29.4 39.4 48.5 57.1 61.3 60.1 53.3 42.1 33.3 24.3 40.7

1 Btu/ft2 day 424 625 943 1317 1602 1762 1689 1510 1209 895 505 347 1069

Providenee,Rl TMAX °F 36.4 37.7 45.5 57.5 67.6 76.6 81.7 SO.3 73.1 63.2 51.9 40.5 59.3TMIN °F 20.0 20.9 29.2 38.3 47.6 57.0 63.3 61.9 53.8 43.1 34.8 24.1 41.2

1 Btu/ft2 day 506 739 1032 1374 1655 1776 1695 1499 1209 907 538 419 1112

Columbia,SC 5602 59.5 67.1 77.0 83.8 89.2 91.9 91.0 85.5 76.5 67.1 58.x 75.3TMIN °F 33.2 34.6 41.9 50.5 59.1 66.1 70.1 69.4 63.9 50.3 40.6 34.7 51.2

1 Btu/ft2 day 762 1021 1355 1747 1895 1947 1842 1703 1439 1211 921 722 1380

SiouxF~s, SD TMAX °F 22.9 29.3 40.1 58.1 70.5 80.3 86.2 83.9 73.5 62.1 43.7 29.3 56.7TMIN °F 1.9 8.9 20.6 34.6 45.7 56.3 61.8 59.7 48.5 36.7 22.3 10.1 33.9

1 Btu/ft2 day 533 802 1152 1543 1894 2100 2150 1842 1410 1005 608 441 1290


Location



Memphis, TN TMAX °F 48.3 53.0 61.4 72.9 81.0 88.4 91.5 90.3 84.3 74.5 61.4 52.3 71.6TMIN °F 30.9 34.1 41.9 52.2 60.9 68.9 72.6 70.8 64.1 51.3 41.1 34.3 51.9

1 Btu/ft2 day 683 945 1278 1639 1885 2045 1972 1824 1471 1205 817 629 1366

Amarillo, TX TMAX °F 49.1 53.1 60.8 71.0 79.1 88.2 91.4 89.6 82.4 72.7 58.7 51.8 70.1TMIN °F 21.7 26.1 32.0 42.0 51.9 61.5 66.2 64.5 56.9 45.5 32.1 24.8 43.8

1 Btu/ft2 day 960 1244 1631 2019 2212 2393 2281 2103 1761 1404 1033 872 1659

Corpus Christi, TX TMAX °F 66.5 69.9 76.1 82.1 86.7 91.2 94.2 94.1 90.1 83.9 75.1 69.3 81.6TMIN °F 46.1 48.7 55.7 63.9 69.5 74.1 75.6 75.8 72.8 64.1 54.9 48.8 62.5

1 Btu/ft2 day 898 1147 1430 1642 1866 2094 2186 1991 1687 1416 1043 845 1521

D~as, TX TMAX °F 54.0 59.1 67.2 76.8 84.4 93.2 97.8 97.3 89.7 79.5 66.2 58.1 76.9TMIN °F 33.9 37.8 44.9 55.0 62.9 70.8 74.7 73.7 67.5 56.3 44.9 37.4 55.0

1 Btu/ft2 day 822 1071 1422 1627 1889 2135 2122 1950 1587 1276 936 780 1468

Houston, TX TMAX °F 61.9 65.7 72.1 79.0 85.1 90.9 93.6 93.1 88.7 81.9 71.6 65.2 79.1TMIN °F 40.8 43.2 49.8 58.3 64.7 70.2 72.5 72.1 68.1 57.5 48.6 42.7 57.4

1 Btu/ft2 day 772 1034 1297 1522 1775 1898 1828 1686 1471 1276 924 730 1351

Midland-Odessa, TX TMAX °F 57.6 62.1 69.8 78.8 86.0 93.0 94.2 93.1 86.4 77.7 65.5 59.7 77.0TMIN °F 29.7 33.3 40.2 49.4 58.2 66.6 69.2 68.0 61.9 51.1 39.0 32.2 49.9

1 Btu/ft2 day 1081 1383 1839 2192 2430 2562 2389 2210 1844 1522 1176 1000 1802

Salt Lake City, UT TMAX °F 37.4 43.7 51.5 61.1 72.4 83.3 93.2 90.0 80.0 66.7 50.2 38.9 64.0TMIN °F 19.7 24.4 29.9 37.2 45.2 53.3 61.8 59.7 50.0 39.3 29.2 21.6 39.3

1 Btu/ft2 day 639 989 1454 1894 2362 2561 2590 2254 1843 1293 788 570 1603

Riclunond, VA TMAX °F 46.7 49.6 58.5 70.6 77.9 84.8 88.4 87.1 81.0 70.5 60.5 50.2 68.8TMIN °F 26.5 28.1 35.8 45.1 54.2 62.2 67.2 66.4 59.3 46.7 37.3 29.6 46.5

1 Btu/ft2 day 632 877 1210 1566 1762 1872 1774 1601 1348 1033 733 567 1248

Seattle, WA TMAX °F 43.9 48.8 51.1 56.8 64.0 69.2 15.2 13.9 68.1 59.5 50.3 45.6 58.9(Sea-Tac airport)

TMIN °F 34.3 36.8 37.2 40.5 46.0 51.1 54.3 54.3 51.2 45.3 39.3 36.3 43.91 Btu/ft2 day 262 495 849 1294 1714 1802 2248 1616 1148 656 337 211 1053

Charleston, WV TMAX °F 41.8 45.4 55.4 67.3 76.0 82.5 85.2 84.2 78.7 67.7 55.6 45.9 65.5TMIN °F 23.9 25.8 34.1 43.3 51.8 59.4 63.8 63.1 56.4 44.0 35.0 27.8 44.0

1 Btu/ft2 day 498 707 1010 1356 1639 1776 1683 1514 1272 972 613 440 1123

Huntington, WV TMAX °F 41.1 45.0 55.2 67.2 75.7 82.6 85.6 84.4 78.7 67.7 55.2 45.2 65.3TMIN °F 24.5 26.6 35.0 44.4 52.8 60.7 65.1 64.0 57.2 44.9 35.9 28.5 45.0

1 Btu/ft2 day 526 757 1067 1448 1710 1844 1769 1580 1306 1004 638 467 1176

Cheyenne, WY TMAX °F 37.3 40.7 43.6 54.0 64.6 75.4 83.1 SO.8 72.1 61.0 46.5 40.4 58.3TMIN °F 14.8 17.9 20.6 29.6 39.7 48.5 54.6 52.8 43.7 34.0 23.1 18.2 33.1

1 Btu/ft2 day 766 1068 1433 1771 1995 2258 2230 1966 1667 1242 823 671 1491

Table 5-Solar Absorptance (a.) forSelected Tank Surfaces"

Solar Absorptance (a.) (dimensionless) Surface Condition

Surface Color Shade or Type Good Poor

Aluminum Specular 0.39 0.49

Aluminum Diffuse 0.60 0.68

Beige/Cream 0.35 0.49

Brown 0.58 0.67

Gray Light 0.54 0.63

Gray Medium 0.68 0.74

Green Dark 0.89 0.91

Red Primer 0.89 0.91

Rust Red iron oxide 0.38 0.50

Tan 0.43 0.55

White 0.17 0.34

Aluminum'' Mili finish, unpainted 0.10 0.15

Notes:aIf specific information is not availab1e, a white shell and roof, withthe paint in good condition, can be assumed to represent the most common or typical tank surface in use.hThis refers to aluminum as the base metal, rather than aluminumco1ored paint.

If the liquid buIk temperature is not available, it may be estimated from Equation 23:

TB = TAA + 60.-1 (23)

where

TB = liquid buIk temperature, in degrees Rankine,

TAA = daily average ambient temperature, in degreesRankine,

a. = tank surface solar absorptance (dimensionless).

The constants, 6 and 1, in Equation 23 have units of degrees Rankine.

19.1.2.2.2.5 Daily Average Liquid SurfaceTemperature, TLA

The daily average liquid surface temperature, TLA, is used to calculate the stock vapor pressure at the daily average liq uid surface temperature, PVA•

If actual daily average liquid surface temperature data for the tank is not available, this temperature can be estimated from Equation 24a:

TLA = 0.44TAA + 0.56TB + 0.OO79a.l (24a)

where

TLA = daily average liquid surface temperature, in degrees Rankine.

TAA = daily average ambient temperature, in degreesRankine.

TB = liquid buIk temperature, in degrees Rankine.


1 = daily total solar insolation on a horizontal surface, in British thermal units per square foot day.

The constants, 0.44 and 0.56, in Equation 24a are dimen sionless. The constant, 0.0079, in Equation 24a has units of degrees Rankine square-foot day per British thermal unit.

Combining Equations 23 and 24a, the daily average liquid surface temperature may altematively be expressed as shown in Equation 24b:

TLA = TAA +0.56 (60.-1) +0.00790.1 (24b)

The calculations of Equations 23 and 24 are based on aheat transfer model that as sumes the liquid and vapor phaseswithin the tank to be in equilibrium with each other and with atmospheric conditions, but does not account for heat transfer effects due to changes in mass (i.e., due to stock liquid of a different temperature entering the tank). This assumption is reasonably valid only when the tank stands idle for an extended period of time. When a tank is frequently filled and emptied, the actual daily average liquid surface temperature, TLA, may deviate significantly from this assumption. In such cases, the use of actual temperature data may significantly improve the accuracy of the loss estimate.

19.1.2.2.2.6 DailyVaporTemperature Range, LiTv

The daily vapor temperature range, I1T v. may be estimated from Equation 25a:

I1T v = O.72I1TA + 0.0280. 1 (25a)

where

I1Tv = daily vapor temperature range, in degrees Rankine.

I1TA = daily ambient temperature range, in degrees Rankine.

= (TAX- TAN)= (TMAX+459.6- TMIN+459.6) =(TMAX- TMIN)

1 = daily total solar insolation on a horizontal surface, inBritish thermal units per square foot day.

where

TLX = daily maximum liquid surface temperature, in degrees Rankine,

TLA = daily average liquid surface temperature, indegrees Rankine,


Given that (TAX- TAN)is equal to (TMAX- TMIN), the daily vapor temperature range can be calculated directly from the meteorological data of Table 4, using Equation 25b.

(25b)

The constant, 0.72, in Equation 25b is dimensionless. Theconstant, 0.028, in Equation 25b has units of degrees Rankinesquare- foot day per British thermal unit.

19.1.2.2.2.7 Daily Maximum and Minimum LiquidSurface Temperatures, ti» ti»

The daily maximum and minimum liquid surface tempera tures, TLX and TLN, respectively, are used for calculating the stock vapor pressures Pvx and PVN•

If data on these liquid surface temperatures are not available, they may be estimated from Equations 26 and 27:

TLX= TLA + 0.2511Tv (26)

TLN = daily minimum liquid surface temperature, in degrees Rankine,

I1T v = daily vapor temperature range, in degreesRankine.

19.1.2.2.2.8 Vapor MolecularWeight, Mv

The stock vapor molecular weight, Mv. can be determined by analysis of vapor samples or by calculation from the com position of the liquido

19.1.2.2.2.8.1 Petroleum Liquid Stocks

The vapor molecular weight of selected petroleum liquids(multicomponent stocks) is given in Table 6.

19.1.2.2.2.8.1.1 Refined Petroleum Stocks

In the absence of specific information, a typical value of 64 pounds per pound-mole can be assumed for gasoline.

19.1.2.2.2.8.1.2 Crude Oil Stocks

In the absence of specific information, a typical value of 50 pounds per pound-mole can be assumed for U. S midconti

TLN= TLA - 0.2511Tv (27) nent crude oils (including both reactive and nonreactive frac-

Table 6-Properties (Mv; Wvc, Pv; A, B) of Selected Petroleum Liquids

Vapor Condensed VaporMolecular Vapor Density Pressure- Vapor Pressure Equation Temperature Range For

Weight (60°F) (at 60°F) Constants? Constants A and B

Petroleum LiquidMv

(lb/lb-mole)Wvc

(lb/gal)Pv

(psia)A

(Dimensionless)B

eR)Minimum

eF)Maximum

eF)

Refined petroleum stocks

Crude oil stocks

Jet naphtha (JP-4) 80 5.4 1.27

e

e

11.368

e

e

5,784.3 40 100

Jet kerosene 130 6.1 0.00823 12.390 8,933.0 40 100

Distillate fuel oil no. 2 130 6.1 0.00648 12.101 8,907.0 40 100

Residual oil no. 6 190 6.4 0.0000430 10.104 10,475.5 40 100

Notes:aVapor pressure calculated at 60°F using constants A and B.hThe vaporpressure equationis Pv= exp [A - (BITL)], where Pvis the vapor pressure in psia, TL is the liquid surface temperature in °R, and exp is the exponential function.cThe vapor pressure equation constants A and B are listed in Equations 31 and 32 for refined petroleum stocks, and Equations 34 and 35 forcrude oil stocks. These constants are from Reference [4].

Sources: The vapor pressure equation constants A and B were developed from a correlation of the vapor pressures given in Reference [5] (except as indicated in Note b). The other properties are also from References [5].

TopLine: oc c TemperatureVaporPressure (psia) at: Bottom Line: °R Range

m

o

es

O

"T

z

'T

Table 7-Properties of Selected Petrochernicals''

Constants for Antoine's Equation''

LiquidDensity at

CAS Molecular 60°F A B C Min. Max.Chemica1Name No. Weight (lb/gal) 40°F 50°F 60°F 70°F 80°F 90°F lOO°F Dimensionless (degrees) (degrees) COF) COF)

Acetaldehyde 00075.{)7-0 44.00 6.576 12.184 8.005 1,600.0 291.81

Acetic acid 00064-19-7 60.05 8.788 0.169 7.387 1,533.3 222.31

Acetic anhydride OOlO8-24-7 lO2.09 9.013 0.053 7.149 1,444.7 199.82(f)

Acetone vv 00067-64-1 58.08 6.628 1.682 2.185 2.862 3.7l3 4.699 5.917 7.251 7.117 1,2lO.6 229.66

"o

14.254 6,920.2 -74.9 418.1 z_"

Acetonitrile e 00075-05-8 41.05 6.558 0.638 0.831 1.083 1.412 1.876 2.456 3.133 7.119 1,314.4 230.00 Im:;:;'U

Acry1amide 00079-06-1 71.09 9.364 0.00009 11.293 3,939.9 273.16~<:m

Acrylic acid 00079-lO-7 72.10 8.864 0.015 0.024 0.037 0.055 0.082 0.119 0.169 8.539 2,305.8 266.55 r O (f)(f)

'T1Acrylonitrilee d 00107-l3-1 53.06 6.758 0.812 0.967 1.373 1.779 2.378 3.133 4.022 7.038 1,232.5 222.47 ;u

14.132 7,191.8 -59.8 173.3 <:

Ally1alcohol e d e 00107-18-6 58.08 7.125 0.135 0.193 0.261 0.387 0.522 0.716 1.006 11.187 4,068.5 392.7 m

Xo

17.107 9,579.2 -4.0 205.9 ::oO

Ally1chloride e de 00107-05-1 76.53 7.864 2.998 3.772 4.797 6.015 7.447 9.1 lO 11.025 5.297 418.4 128.17 O

14.456 6,689.5 -94.0 112.3 :;lAAniline 00062-53-3 93.10 8.529 0.006 7.320 1,731.5 206.05 (f)

Benzene ? 00071-43-2 78.11 7.365 0.638 0.870 1.160 1.508 1.972 2.6lO 3.287 6.905 1,211.0 220.79

Butane (-n) e f 58.12 5.007 25.960 6.809 935.9 238.73

Butene (2-methy1-1) 70.13 5.420 10.246 6.486 1,039.7 236.65

Buty1alcohol (-n) e 00071-36-3 74.12 6.760 0.057 7.477 1,362.4 178.77

{butano1(-1)}

Buty1alcohol (-tert) 00075-65-0 74.12 6.595 0.174 0.290 0.425 0.638 0.909 1.238 1.702

17.223 9,430.3 -4.7 432.5 ~

Table 7-Properties of Selected Petrochemicals" (Continued) N N

Constants for Antoine's Equatioré'

oC°R B

(degrees)

oC TemperatureRange

Topline:Bottom

Line: ADimensionless

LiquidDensity at

60°F (lb/ga1)

Vapor Pressure (psia) at:

CASNo.

MolecularWeight

C(degrees)

Min.COF)

Max.COF)

Chemical Name

40°F

50°F

60°F

70°F

80°F

90°F

lOO°F

o

»

<

Buty1 chloride (-n) e e 00lO9-69-3 92.57 7.430 0.715 1.006 l.320 1.740 2.185 2.684 3.481 6.837 1,173.8 218.13

Buty1 ether (di-t) 06163-66-2 130.23 6.400 0.647 6.933 1,348.5 233.79

Carbon disu1fide e d 00075-15'{) 76.13 lO.588 3.036 3.867 4.834 6.014 7.387 9.185 11.215 6.942 1,169.1 241.59

l3.329 6,146.2 -lOO.8 492.8Carbon tetrachloride e d 00056-23-5 153.84 l3.366 0.793 1.064 1.412 1.798 2.301 2.997 3.771 6.934 1,242.4 230.00

Ol3.522 6,908.7 -58.0 528.8 I»

'UChlorobenzene 00lO8-90-7 112.60 9.239 0.133 6.978 1,431.1 217.55

"m;u"_"

<D

Chlorobutane (-1) 00lO9-63-9 92.57 7.380 1.261 6.837 1,173.8 218.13 I:;;'U

Chlorobutane (-2) 00078-864 92.57 7.270 2.007 6.799 1,149.1 224.68~<:m

Chloroform e d 00067-66-3 119.39 12.488 1.528 1.934 2.475 3.191 4.061 5.163 6.342 6.493 929.4 196.03 r O (f)

l3.865 6,792.5 -72.4 489.2 (f)

Chloroprene e 00126-99-8 88.54 8.046 1.760 2.320 2.901 3.655 4.563 5.685 6.981 6.161 783.5 179.70 s::(f)e;u

Chloroto1uene (--o) 00095-49-8 126.59 9.020 0.039 7.368 1,735.8 230.00 mmz

""Creso1 (-m) 00lO8-394 108.10 8.629 0.0014 7.508 1,856.4 199.07

Creso1 (--o) d 00095-48-7 108.14 8.738 0.002 6.911 1,435.5 165.16

16.296 11,308.6 lOO.8 375.4

Creso1 (-p) 00lO6-44-5 108.10 8.629 0.0006 7.035 1,511.1 161.85

Cyclohexane e 00110-82-7 84.16 6.522 0.677 0.928 1.218 1.605 2.069 2.6lO 3.249 6.841 1,201.5 222.65

Cyclohexano1 d 00lO8-93'{) 100.20 8.029 0.002 6.255 912.9 lO9.13

l3.697 7,091.7 -49.5 495.5

Cyclohexanone 00lO8-94-1 98.20 7.9lO 0.054 7.849 2,l37.2 273.16

:;:

;

l3.804 7,200.2 -48.1 545.0

O

(f

Cyclohexene 00110-83-8 82.15 6.750 1.098 6.886 1,230.0 224.10

Cyclopentane e de 00287-92-3 70.13 6.248 2.514 3.287 4.177 5.240 6.517 8.063 9.668 6.887 1,124.2 231.36

14.338 6,711.5 -90.4 120.7

Cyclopentanone 00120-92-3 84.12 7.900 0.132 2.902 162.9 63.22

(f)

Cyclopentene 00142-29-0 68.12 6.430 3.263 6.921 1,121.8 223.45 mo

"ezs"_"Decane (-n) d 00124-18-5 142.29 6.092 0.021 0.026 0.033 0.042 0.053 0.066 0.083 I

15.046 9,882.0 62.8 343.4 m

Dibromopropane (1,2) 00078-75-1 201.89 16.100 0.089 7.304 1,644.4 232.00 'oU

~<:Dibromopropane (1,3) 00109-64-8 201.89 16.510 0.027 7.550 1,890.6 240.00 m

r O (f)(f)

Dichloroethane (1,1) e e 00075-34-3 98.97 9.861 1.682 2.243 2.901 3.771 4.738 5.840 7.193 6.977 1,174.0 229.06 'T1

O<:"Tl

Dichloroethane (1,2) e d

00107-06-2 98.97 10.500 0.561 0.773 1.025 1.431 1.740 2.243 2.804 7.025 1,272.3 222.90 Xm

::oDichloroethy1ene 00540-59-0 96.95 10.763 1.450 2.011 2.668 3.461 4.409 5.646 6.807 7.022 1,205.4 230.6 O

'T1(cis-1,2)ce :;lz

Dichloroethy1ene 00156-60-5 96.95 10.524 2.552 3.384 4.351 5.530 6.807 8.315 10.016 6.965 1,141.9 231.90 A

(trans-1,2) e

Dichloroto1uene(3,4) 161.03 10.470 0.003 7.344 1,882.5 215.00

Diethoxyethane (1,1) 00105-57-7 118.18 6.920 0.394 6.758 1,191.6 203.12

Diethoxymethane 104.15 6.990 0.810 6.908 1,229.5 217,Ol

Diethy1(n,n) aniline 00091-66-7 149.23 7.763 0.002 7.466 1,993.6 218.50

Diethy1ketone 00096-22-0 86.13 6.780 0.402 6.858 1,216.3 204.00

Nw

Table 7-Properties of Selected Petrochemicals" (Continued) N.¡:,.


oC°R B

(degrees)

oC TemperatureRange

Topline:Bottom

Line: ADimensionless

LiquidDensity at

60°F (lb/ga1)

Vapor Pressure (psia) at:

CASNo.

MolecularWeight

C(degrees)

Min.COF)

Max.COF)

Chemical Name

40°F

50°F

60°F

70°F

80°F

90°F

lOO°F

'

e

Diethy1 sulfide 00352-93-2 90.18 6.970 0.699 6.928 1,257.8 218.66

Diethy1amine e de 00lO9-89-7 73.14 5.906 1.644 1.992 2.862 3.867 4.892 6.130 7.541 5.802 583.3 144.1l3.788 6,617.7 -27.4 4lO.0

Diethy 1benzene (l ,2) 134.22 7.330 0.009 6.988 1,576.9 200.51

Diethy1benzene (l,3) 134.22 7.170 O.OlO 7.004 1,575.3 200.96OI

Diethy1benzene (l,4) 134.22 7.180 O.OlO 6.998 1,588.3 201.97 »

"m;u"_"

Di-isopropy1 ether e e 00lO8-20-3 102.17 6.075 1.199 1.586 2.127 2.746 3.481 4.254 5.298 6.850 1,l39.3 218.70 <D

Im

Dimethoxyethane (l,2) 00110-714 90.12 7.220 2.146 6.719 1,050.5 209.20 :;;'oU

~ Dimethy1 formamide 00068-12-2 73.09 7.578 0.040 6.928 1,400.9 196.43 <:

mr O (f)

Dimethy1 hydrazine (1,1) 00057-14-7 60.10 7.882 1.895 7.408 1,305.9 225.53 (f)

s::m»

Dimethy1 phthalate 00131-11-3 194.20 9.965 0.00000002 4.522 700.3 51.42 (f)

;u m<:

Dimethy1butane (2,3) 86.18 5.510 3.058 6.8lO 1,127.2 228.90 mz

""Dimethy1cyclopentane 87.50 6.290 0.932 6.817 1,219.5 221.95 (l,1)Dimethy1pentane (2,2) 100.20 5.610 l.316 6.815 1,190.0 223.30

Dimethy1pentane (2,3) 100.20 5.790 0.841 6.854 1,238.0 221.82

Dimethy1pentane (2,4) 100.20 5.600 1.459 6.826 1,192.0 225.32

Dimethy1pentane (3,3) 100.20 5.780 1.029 6.827 1,228.7 225.32

Dioxane (1,4) e 00123-91-1 88.10 8.659 0.232 0.329 0.425 0.619 0.831 1.141 1.508 7.431 1,554.7 240.34

'

(f

<

Dipropy1ether e e 00111-43-3 102.17 6.260 0.425 0.619 0.831 1.102 1.431 1.876 2.320 6.948 1,256.5 219.00

Epichlorohydrin 00106-89-8 92.50 9.848 0.194 8.229 2,086.8 273.16

Ethanolamine (mono-) 00141-43-5 61.09 8.344 0.002 7.456 1,577.7 173.37

(f)Ethy1acetate e d 00141-78-6 88.10 7.551 0.580 0.831 1.102 1.489 1.934 2.514 3.191 7.101 1,245.0 217.88 mo

14.478 7,517.5 -46.1 455.0 "ezs"Ethy1acry1atee 00140-88-5 100.11 7.750 0.2l3 0.290 0.425 0.599 0.831 1.122 1.470 7.965 1,897.0 273.16 _"

ImEthy1alcohol e d 00064-17-5 46.07 6.610 0.193 0.406 0.619 0.870 1.218 1.682 2.320 8.321 1,718.2 237.52 :;:;

{ethano1} 16.380 8,760.7 -24.3 467.6 O

Ethy1chloride 00075'{)0-3 64.52 7.678 16.591 6.986 1,030.0 238.61 ~ m r O

Ethy1ether e 00060-29-7 74.12 5.988 4.215 5.666 7.019 8.702 10.442 l3.342 6.920 1,064.1 228.80 (f)

'T1{diethy1ether} ;U

OEthy1amine 00075'{)4-7 45.08 5.690 14.103 7.054 987.3 220.00 <:

"Tl X

moEthy1benzened 00100-41-4 106.17 7.227 0.109 6.975 1,424.3 2l3.21 ::o

O14.036 8,423.3 14.4 619.7 O'T1

Ethy1cyclopentane 98.19 6.380 0.475 6.887 1,298.6 220.68 :;l z A (f)

Ethy1eneoxide 00075-21-8 44.00 7.227 17.842 7.128 1,054.5 237.76

Ethy1pentane(-3) 100.20 5.820 0.700 6.876 1,251.8 219.89

Fluorobenzene 00462-06-6 96.10 8.520 0.937 7.187 1,381.8 235.60

Formic acid 00064-18-6 46.00 10.182 0.521 7.581 1,699.2 260.70

Freon 11 e 00075-69-4 l37.38 12.480 7.032 8.804 10.900 l3.401 16.311 19.692 23.600 6.884 1,043.0 236.88{trichlorofluoromethane}

Furan 00110-00-9 68.08 7.821 7.961 6.975 1,060.9 227.74

NCJ1

Topline: oC oC TemperatureBottom Line: °R Range

'

m

»

m

;

s:

Table 7-Properties of Selected Petrochemicals" (Continued)

LiquidDensity at VaporPressure (psia) at:


CAS Molecular 60°F A B C Min. Max. Chemical Name No. Weight (lb/ga1) 40°F 50°F 60°F 70°F 80°F 90°F 100°F Dimensionless (degrees) (degrees) COF) COF)

Furfura1 00096-01-1 96.09 9.648 0.014 6.575 1,198.7 162.80

Heptane (_n)cde 00142-82-5 100.20 5.727 0.290 0.406 0.541 0.735 0.967 1.238 1.586 6.897 1,264.9 216.54l3.984 7,615.8 -29.2 477.5

Heptene (-1) 98.19 5.810 0.677 6.902 1,258.3 219.30

Hexadiene (l,5) 82.15 5.730 2.890 6.574 1,0l3.5 214.80OI

Hexane (-n) e d 00110-54-3 86.17 5.527 1.102 1.450 1.876 2.436 3.055 3.906 4.892 6.876 1,171.2 224.41 »

l3.824 6,907.2 --65.0 408.9 "m;

u"_"

Hexano1(-1) 00111-27-3 102.18 6.760 0.007 7.860 1,76l.3 196.66 <D

I:;;

Hydrogen cyanide e 00074-90-8 27.03 5.772 6.284 7.831 9.514 11.853 15.392 18.563 22.237 7.528 1,329.5 260.40 'oU

{hydrocyanic acid} ~Isobuty1alcohol e 00078-83-1 74.12 6.712 0.058 0.097 0.135 0.193 0.271 0.387 0.541 7.474 1,314.2 186.55 <:

r O (f)

Isooctane e e 26635-64-3 114.22 5.794 0.2l3 0.387 0.580 0.812 1.093 1.392 1.740 6.812 1,257.84 220.74 (f)

m(f)

Isopentane e e 00078-784 72.15 5.199 5.878 7.889 10.005 12.530 15.334 18.370 21.657 6.833 1,040.7 235.45 em<:

Isoprenev= 00078-79-5 68.11 5.707 4.757 6.130 7.677 9.668 11.699 14.503 17.113 7.012 1,126.2 238.88 z""Isopropy1alcohol e d 00067-63'{) 60.09 6.573 0.2l3 0.329 0.483 0.677 0.928 1.296 1.779 8.118 1,580.9 219.61

{isopropano1} 16.769 9,1l3.6 -15.0 449.6Isopropy1benzene d 00098-82-8 120.20 7.211 0.051 6.963 1,460.8 207.78

{cumene} 15.009 9,359.7 37.2 306.3Isopropy1benzene 00527-844 134.22 7.300 0.014 6.940 1,548.1 203.15

(l-methyl-2)Methacrylonitrilee e 00126-98-7 67.09 6.738 0.483 0.657 0.870 1.160 1.470 1.934 2.456 6.980 1,275.0 220.70

Methy1acetate e d 00079-20-9 74.08 7.831 1.489 2.011 2.746 3.693 4.699 5.762 6.961 7.065 1,157.6 219.7314.334 7,002.9 -71.0 437.0

Methy1acry1atee d 00096-33-3 86.09 7.996 0.599 0.773 1.025 1.354 1.798 2.398 3.055

14.997 7,786.4 -46.7 176.4

Table 7-Properties of Selected Petrochernicals'' (Continued)

Constants for Antoine's Equation'' oc

°RB

oc TemperatureRange

TopLine:Bottom Line:

A

LiquidDensity at

60°F

VaporPressure (psia) at:

CAS Molecular C Min. Max.Chemica1Name No. Weight (lb/gal) 40°F 50°F 60°F 70°F 80°F 90°F lOO°F Dimensionless (degrees) (degrees) COF) COF)

Methy1alcohol e d 00067-56-1 32.04 6.630 0.735 1.006 1.412 1.953 2.610 3.461 4.525 7.897 1,474.1 229.13{methano1} 15.948 8,l3l.3 -47.2 435.2

Methy1ethy1ketone e d 00078-93-3 72.10 6.747 0.715 0.928 1.199 1.489 2.069 2.668 3.345 6.974 1,209.6 216.0014.381 7,380.2 -54.9 175.3

Methy1isobuty1ketone OOlO8-10-1 100.20 6.677 0.212 6.672 1,168.4 191.90

(f)Methy1methacry1atee d 00080-62-6 100.11 7.909 0.116 0.213 0.348 0.541 0.773 1.064 1.373 8.409 2,050.5 274.40 mo

14.800 8,127.7 -22.9 2l3.8 "ezs"Methy1propy1eíher ? 00557-17-5 74.12 6.166 3.674 4.738 6.091 7.058 9.417 11.602 13.729 6.119 708.7 179.90 _"

ImMethy1styrene (a1pha) 00098-83-9 118.00 7.586 0.024 6.923 1,486.9 202.40 :;:;

'o

U

Methy1cyclohexanee 00108-87-2 98.18 6.441 0.309 0.425 0.541 0.735 0.986 l.315 1.721 6.823 1,270.8 221.42

Methy1cyclopentanee 00096-37-7 84.16 6.274 0.909 1.160 1.644 2.224 2.862 3.616 4.544 6.863 1,186.1 226.04

~<:mr O (f)(f)

'T1;uO

Methy1dichlorosilane 129.06 8.910 5.718 7.028 1,167.8 240.70 <: "Tl X

moMethy1enechloride e d

00075-09-2 84.94 11.122 3.094 4.254 5.434 6.787 8.702 lO.329 13.342 7.409 1,325.9 252.60 ::oO

14.897 6,857.5 -94.0 lO5.3 O'T1

Methylhexane (-2) 100.21 5.660 0.799 6.873 1,236.0 219.55 :;l z A (f)

Methylhexane (-3) 100.21 5.720 0.744 6.868 1,240.2 219.22

Methy1pentane(-2) 86.18 5.440 2.731 6.839 1,l35.4 226.57

Methy1-tert-buty1ether g 01634-04-4 88.15 6.200 1.920 2.500 3.220 4.1 lO 5.180 6.470 8.000 6.867 1,116.1 224.74{MTBE}

Morpholine 00llO-91-8 87.12 8.337 0.109 7.718 1,745.8 235.00

Naphthalene s l' 128.17 9.555 0.0007 7.011 1,733.7 201.86

Nitrobenzene 00098-95-3 123.10 10.057 0.002 7.115 1,746.6 201.80

N-.,,¡

Topline: oC oC TemperatureBottom Line: °R Range

Nonane (-n) 00111-84-2 128.26 5.992 0.040 0.051 0.065 0.083 0.106 0.135 0.17115.241 9,469.8 36.3 301.1

Octane (-n) de 00111-65-9 114.23 5.867 0.087 0.112 0.145 0.188 0.244 0.315 0.408 6.920 1,352.0 209.1514.231 8,350.6 6.8 538.5

Octano1(-1) 00111-87-5 130.23 6.890 0.0008 12.070 4,506.8 319.90OI

Pentachloroethane 00076-01-7 202.30 l3.947 0.035 6.740 1,378.0 197.00 »

"m;u"_"

6.918 1,105.0 228.85 <D

CX

m

»

m

;

s:

Table 7-Properties of Selected Petrochemicals" (Continued) N


Liquid VaporPressure (psia) at:Density atCAS Molecular 60°F A B C Min. Max.

Chemical Name No. Weight (lb/ga1) 40°F 50°F 60°F 70°F 80°F 90°F 100°F Dimensionless (degrees) (degrees) COF) COF)Nitromethane e e 00075-52-5 61.04 9.538 0.2l3 0.251 0.348 0.503 0.715 1.006 1.334 7.282 1,446.9 227.60

'U

Pentadiene (l,2) 68.12 5.770 4.827I

:;;Pentadiene (l,4) 68.12 5.490 10.019 6.835 1,018.0 231.46 'oU

~Pentadiene (2,3) 68.12 5.790 4.160 6.962 1,126.8 227.84 <:

r O (f)

Pentane (-n) e de 00109-66'{) 72.15 5.253 4.293 5.454 6.828 8.433 10.445 12.959 15.474 6.853 1,064.8 233.01 (f)

l3.300 5,972.6 -105.9 376.3 m(f)

Pentene (-1) 00109-67-1 70.14 5.330 8.688 6.844 1,044.0 233.50 em<:

Pentyne (-1) 68.12 5.760 5.663 6.967 1,092.5 227.18 z""Pheno1dh 94.11 8.937 0.006

15.658 10,769Phosgene 00075-44-5 98.92 11.500 19.788 6.843 94l.3 230.00

Picoline (-2) 00108-99-6 93.12 7.928 0.122 7.032 1,415.7 211.63

Propanethio1(-1) 76.16 7.010 1.942 6.928 1,183.3 224.62

Propanethio1(-2) 76.16 6.830 3.595 6.877 1,1l3.9 226.16

Propy1alcohol (-n) 00071-23-8 60.10 6.700 0.212 7.848 1,499.2 204.64

{propano1(-1)}

Table 7-Properties of Selected Petrochernicals'' (Continued)

Constants for Antoine's Equation'' oc

°RB

oc TemperatureRange

TopLine:Bottom Line:

A

LiquidDensity at

60°F

VaporPressure (psia) at:

CAS Molecular C Min. Max.

Propy1eneoxide 00075-66-9 58.10 7.169 6.674 8.277 1,656.9 273.16

Chemica1Name No. Weight (lb/gal) 40°F 50°F 60°F 70°F 80°F 90°F 100°F Dimensionless (degrees) (degrees) COF) COF)Propy1nitrate (-n) 00627-l3-4 105.09 8.780 0.262 6.955 1,294.4 206.70

Propy1arnine(-n)ce 00107-10-8 59.11 6.030 2.456 3.191 4.157 5.250 6.536 8.044 9.572 6.927 1,044.1 210.84

Propy1eneglyco1 00057-55-6 76.11 8.646 0.0009 8.208 2,085.9 203.54

(f)

"ezs"Pyridine 00110-86-1 79.10 8.162 0.233 7.041 1,373.8 214.98 _"

ImResorcino1 00108-46-3 110.11 10.616 0.00007 6.924 1,884.5 186.06 :;:;

'oU

~ Styrcnc+ 00100-42-5 104.15 7.560 0.072 7.140 1,574.5 224.09 <:

m14.295 8,725.2 19.4 293.4 r

O (f)Tetrachloroethane 00630-20-6 167.85 13.336 0.132 6.898 1,365.9 209.74 (f)

'T1(1,1,1,2) ;u

OTetrachloroethane 00079-34-5 167.85 13.236 0.043 6.631 1,228.1 179.90 <:

"Tl

(1,1,2,2) mXo

Tetrachloroethylene 00127-18-4 165.83 13.545 0.207 6.980 1,386.9 217.53 ::o o o'T1

Tetrahydrofuran 00109-99-9 72.12 7.421 2.038 6.995 1,202.3 226.25 :;l z A (f)

To1uenecd 00108-88-3 92.13 7.261 0.174 0.213 0.309 0.425 0.580 0.773 1.006 6.954 1,344.8 219.48l3.829 7,770.6 -16.1 606.2

Trichloroethane (1,1,1) e d 00071-55-6 l33.42 11.216 0.909 1.218 1.586 2.030 2.610 3.307 4.199 8.643 2,l36.6 302.8014.373 7,256.4 -61.6 165.4

Trichloroethane (1,1,2) 00079-00-5 l33.40 11.163 0.245 6.951 1,314.4 209.20

Trichloroethy1enee d 00079-01-6 l31.40 12.272 0.503 0.677 0.889 1.180 1.508 2.030 2.610 6.518 1,018.6 192.7014.374 7,529.8 -46.8 188.1

Trichloropropane (1,2,3) 00096-18-4 147.43 11.575 l39.194 6.903 788.2 243.23

Trifluoroethane 00076-l3-1 187.38 13.178 4.376 6.880 1,099.9 227.50(trichloro 1,1,2) N

<D

9,054.71,453.4 215.31

Density at

m

oTable 7-Properties of Selected Petrochemicals" (Continued) w

Liquid VaporPressure (psia) at:


TopUne: -cBottom Line: °R

TemperatureRange

Chemical NameCAS No.

MolecularWeight

60°F (lb/ga1)

A BDimensionless (degrees)

C(degrees)

Trimethy1benzene(1,2,4) 95-63-6 120.19 7.290 0.021 7.044 1,573.3 208.56

Trimethy1chorosilane 108.64 7.130 3.034 7.056 1,245.5 240.70

Trimethy1pentane(2,2,3) 114.23 5.970 0.378 6.825 1,294.9 218.42

Trimethy1pentane(2,2,4){isooctane}

00540-84-1 114.23 5.760 0.2l3 0.387 0.580 0.812 1.093 1.392 1.740 6.812 1,257.8 220.74o

I»Trimethy1pentane(2,3,3) 114.23

Undecane (-n) e f 156.32

6.050 0.317 6.844 1,328.1

6.184 0.003 6.972 1,569.6

220.38 ~m;u_"

187.7 l'Vmy1 acetate e d 00108-054

86.09 7.817 0.735 0.986 1.296 1.721 2.262 3.1l3 4.022 7.21015.032

1,296.17,670.9

226.66 ~o-54.4 162.5 ~

Vmylidenechloride e d 00075-354 96.50 10.383 4.990 6.344 7.930 9.806 11.799 15.280 23.210 6.97214.676

1,099.46,531.1

237.20-107.0 89.1

~ro(f)

Xy1ene(-m) 0l330-20-7 106.17 7.244 0.129 7.009 1,462.3 215.11 (f)

s::~

Xy1ene(--o) d 00095-47-6 106.17

Xy1ene(_p)ef 106.17

7.345 0.071 6.99814.815

7.185 0.096 6.991

1,474.7 213.69 e;um25.2 291.9 <:mz""

Notes:aSources:The properties are from the TANKS software prograrn published by the United States Environmenta1ProtectionAgency, version 4.08, except where noted otherwise.~e top line ofthe entries for Antoine's equation has 3 constants for use in Equations 36, 37, and 38. The bottom line ofthese entries has 2 constants foruse in Equations 28, 29, and 30.cSources:Values for the vapor pressures at 10-degreeFahrenheit increments of temperature are from API Bulletin 2523, PetrochemicalEvaporation Loss From Storage Tanks,First Edition, Washington,D.C., November 1969.dSources:Va1uesof A and B for the 2-constantAntoine's equation are fromAPI Manual of PetroleumMeasurement Standards Chapter 19.1, Evaporative Lossfrom Fixed-RoofTanks, Second Edition, Washington, D.C., October 1991.eSources:Values of A, B, and C for the 3-<:onstanAt ntoine's equation are from API Manual of PetroleumMeasurement Standards Chapter 19.4, Recommended Practicefor Speciation of Evaporative Losses,First Edition, Washington,D.C., November 1997.fSources:Values for the molecular weight and liquid density are from Reference [6].Va1uesfor the vapor pressure at 60 degrees Fahrenheit are fromAPI Manual ofPetroleum Measurement Standards Chapter19.4, Recommended Practicefor Speciation of Evaporative Losses, First Edition, Washington,D.C., November 1997.gSources:Va1uesof A, B, and C for the 3-constant Antoine's equation are from Lisal, M., Smith, W.R., and Nezbeda, l., "Accurate Computer Simu1ationof Phase Equilibrium for Comp1exFluid Mixtures. Application to Binaries Invo1vingIsobutene, Methano1,Methy1tert-Buty1Ether, and n-Butane," J. Phys. Chem. B 1999, 103, 10496-10505.hSources:Va1uesfor the molecular weight, the liquid density and the vapor pressure at 60 degrees Fahrenheit are fromAPI Manual of PetroleumMeasurement Standards Chapter 19.1, Evaporative LossfromFixed-RoofTanks, Second Edition, Washington,D.C., October 1991.


tions). Since a large variability in vapor molecular weights has been observed in foreign crude oils, no average value has been developed for these stocks.

19.1.2.2.2.8.2 Petrochemical Stocks

For single-component petrochemical stocks, the molecular weight of the vapor is equal to the molecular weight of the liq uid, which is given in Table 7 for selected petrochemicals.

19.1.2.2.2.9 Daily Maximum,Average,and MinimumVapor Pressures, Pvx. PVA, PVN

The stock vapor pressure must be determined at three different temperatures:

a. The daily maximum liquid surface temperature, TLX.

b. The daily average liquid surface temperature, TLA,

c. The daily minimum liquid surface temperature, TLN•

These three liquid surface temperatures are discussed in19.1.2.2.2.5 and 19.1.2.2.2.7. The corresponding three stock vapor pressures, Prx PVA, and PVN, can be calculated from Equations 28, 29, and 30, respectively:

Prx= exp [A - (B/TLX)] (28)

PVA =exp [A-(B/TLA)] (29)

PVN = exp [A - (B/TLN)] (30)

where

Pvx = stock vapor pressure at the daily maximum liq uid surface temperature, in pounds per square inch absolute,

PVA = stock vapor pressure at the daily average liquid surface temperature, in pounds per square inch absolute,

PVN = stock vapor pressure at the daily minimum liq uid surface temperature, in pounds per square inch absolute,


TLA = daily average liquid surface temperature, in degrees Rankine,


A = constant in the vapor pressure equation (dimensionless),

B = constant in the vapor pressure equation, in degrees Rankine,

exp = exponential function.


For selected petroleum liquid stocks, the stock vapor pressure may be calculated from Equations 28, 29, and 30, where the constants A and B are listed in Table 6.

19.1.2.2.2.9.1.1 Refined Petroleum Stocks

For refined petroleum stocks, the stock vapor pressure maybe determined from Figure 5 or calculated from Equations28, 29, and 30. For refined petroleum stocks, the constants A and B are functions of both the Reid vapor pressure, RVP, and the ASTM Distillation Slope, S. The constants A and B can be determined from Figures 3 and 4 or calculated from Equa tions 31 and 32, respectively:

A = 15.64 -1.854:fJ.5 - (0.8742 - 0.3280 :fJ.5) In(RVP) (31)

B = 8742-1042:fJ.5 -(1049 -179.4 :fJ.5) In (RVP) (32)

where

RVP = stock Reid vapor pressure, in pounds per square inch,

s = stock ASTM-D86-Distillation ofPetroleumProducts distillation slope at 10 volume percentevaporated, in degrees Fahrenheit per volume percent,

In = naturallogarithm function.

The slope, S, is the slope of the ASTM-D86 distillation data at 10 volume percent evaporated and can be calculated from the distillation data using Equation 33:

where

(33)

S = stock ASTM-D86 distillation slope at 10 volume percent evaporated, in degrees Fahrenheitper volume percent,

T5 = temperature at which 5 volume percent is evaporated, in degrees Fahrenheit,

T15 = temperature at which 15 volume percent is evaporated, in degrees Fahrenheit.

The constant, 10, in Equation 33 has units of volume percent.

Figure 3-Vapor Pressure Function Coefficient (A) of Refined Petroleum Stocks with a

Reid Vapor Pressure of 1 to 20 psi, Extrapolated to 0.1 psi

Figure 4-Vapor Pressure Function Coefficient (B) of Refined Petroleum Stocks with a

Reid Vapor Pressure of 1 to 20 psi, Extrapolated to 0.1 psi

Figure 5- True Vapor Pressure (Pv) of Refined Petroleum Stocks with aReid Vapor Pressure of 1 to 20 psi

ReidVapor 10 VolumePercentRefined Pressure Evaporated

Petroleum Stock

Aviation gasoline

RVP, (psi) S, eF/vol. %)

2.0

Naphtha 2-8 2.5

Motor gasoline 3.0

Light naphtha 9-14 3.5

Table 8-ASTM Distillation Slope (S) for SelectedRefined Petroleum Stocks

ASTM-D86Distillation Slope at

In the absence of ASTM-D86 distillation data on refined petroleum stocks, approximate values of the distillation slope, S, from Table 8 may be used.

19.1.2.2.2.9.1.2 Crude Oil Stocks

For crude oil stocks, the stock vapor pressure may be deter

mined from Figure 8 or calculated from Equations 28, 29, and30. For crude oil stocks, the constants A and B are functions of only the Reid vapor pressure, RVP, and can be determined from Figures 6 and 7 or calculated from Equations 34 and 35, respectively:

A = 12.82- 0.9672ln(RVP) (34)

B = 7261 - 1216ln(RVP) (35)

where

RVP = stock Reid vapor pressure, in pounds per square inch,

In = naturallogarithm function.


For selected petrochemical stocks, the stock vapor pressure may be calculated from Equation 28, 29, and 30, where the constants A and B are from the 2-constant form of Antoine's equation. The 2-constant values of A and B are listed on the bottom line of the entry for Antoine's equation constants in Table 7, for those chemicals for which values are provided. Use of the values of A and B from the 3-constant form of Antoine's equation would yield meaningless results.

The loss equations are applicable to nonboiling stocks, although volatile stocks with a true vapor pressure over 1.5 pounds per square inch absolute are not now typically stored in the U.S. in fixed-rooftanks.

Altematively,a more accurate estimation of the vapor pres sure of petrochemical stocks may be calculated from

Equa tions 36, 37, and 38, which use a 3-constant form of Antoine's

equation rather than the 2-constant form used in Equations28,29, and 30.

Pvx = 0.019337 log-l rA- B 1 (36)(5 ~LX _ 273.15) + C

PVA = 0.019337 log-l rA- B 1 (37)(5 ~LA-273.15) +C

PVN = 0.019337 log-l rA- B 1 (38)(5 ~LN -273.15) +C

where


PVA = stock vapor pressure at the daily average liquid surface temperature, in pounds per square inch absolute,

PVN = stock vapor pressure at the daily minimum liq uid surface temperature, in pounds per square inch absolute,


TLA = daily average liquid surface temperature, in degrees Rankine,


A = constant in the vapor pressure equation (dimensionless),

B = constant in the vapor pressure equation, in degrees Celsius,

C = constant in the vapor pressure equation, in degrees Celsius.

The constant, 0.019337, is a conversion factor with units of pounds per square inch absolute per millimeter of mercury. The terms (5TLX/ 9- 273.15), (5TLA /9- 273.15), and (5TLN

/9 - 273.15) convert the liquid surface temperatures, TLX,

TLA, and TLN, from degrees Rankine to degrees Celsius. The constants A, B, and C are listed in Table 7 for selected petro chemicals. The 3-constant values of A, B, and C are listed on

35

SECTION 1-EvAPORATIVE Loss FROM FIXED-RoOF TANKS

Figure 6-Vapor Pressure Function Coefficient (A) of Crude Oil Stocks with a Reid Vapor

Pressure of 2 to 15 psi, Extrapolatedto 0.1 psi

Figure 7-Vapor Pressure Function Coefficient (8) of Crude Oil Stocks with a Reid Vapor

Pressure of 2 to 15 psi, Extrapolatedto 0.1 psi


Figure 8---True Vapor Pressure (Pv) of Crude Oil Stocks with a ReidVapor Pressure of 2 to 15 psi


the top line of the entry for Antoine's equation constants inTable 7, for those chemicals for which values are provided.

19.1.2.2.2.10 Daily Vapor Pressure Range, LiPv

The stock daily vapor pressure range, Mv. can be calculated from Equation 39a:

MV=PVX-PVN (39a)

19.1.2.2.2.11 Breather Vent Pressure SettingRange,LiPs

The breather vent pressure setting range, MB, is used inEquation 14 and may be calculated from Equation 40:

(40)

where

~B = breather vent pressure setting range, in poundswhere per square inch,

Mv = stock daily vapor pressure range, in pounds per square inch,


PVN = stock vapor pressure at the daily minimum liq uid surface temperature, in pounds per square inch absolute.

In order to calculate the stock daily vapor pressure range, Mv. from Equation 39a, it is first necessary to determine the stock vapor pressure at the daily maximum liquid surface temperature, TLX, and at the daily minimum liquid surface temperature, TLN• These temperatures are discussed in19.1.2.2.2.7.

An approximate method of estimating the stock daily vapor pressure range is from Equation 39b:

PBP = breather vent pressure setting (always a positive value), in pounds per square inch gauge,

PBV = breather vent vacuum setting (always a negativevalue), in pounds per square inch gauge.

The breather vent pressure setting, PB/J, and breather vent vacuum setting, PBv. should be available from the tank owner or operator.

If specific information on the breather vent pressure setting and vacuum setting is not available, as sume +0.03 pounds per square inch gauge for PBP and -0.03 pounds per square inch gauge for PBf7.

If the fixed-roof tank is of bolted or riveted construction inwhich the roof or shell plates are not gas tight, as sume that MB is O pounds per square inch, even if a breather vent is used.

19.1.2.2.2.12 Vented Vapor Saturation Factor, Ks

where

I1Pv = 0.05 B P~A I1T V

TLA(39B) The vented vapor saturation factor, Ks, accounts for the

degree of stock vapor saturation in the vented vapor. The vented vapor saturation factor may be estimated from Equa tion 5 or determined from Figure 9.

Mv = stock daily vapor pressure range, in pounds persquare inch,

B = constant in the vapor pressure equation, in degrees Rankine, where

K s = 1-:----=-=-==--=--::-::--1 +0.053 PVA tt ¿

(5)

PVA = stock vapor pressure at the daily average liquidsurface temperature, in pounds per square inch absolute,

TLA = daily average liquid surface temperature, indegrees Rankine,

I1T v = daily vapor temperature range, in degreesRankine.

Although Equation 39b is less accurate than Equation 39a, it is easier to use since it requires the stock vapor pressure at only the daily average liquid surface temperature, TLA•

Ks = vented vapor saturation factor, (dimensionless),

PVA = stock vapor pressure at the daily average liquid surface temperature, in pounds per square inchabsolute,

Hvo = vapor space outage, in feet.

The constant, 0.053, in Equation 5 has units of [(pounds per square inch absolute) feeW 1.

19.1.2.2.2.13 Condensed Vapor Density, Wvc


For selected petroleum liquid stocks, the stock condensed vapor density at 60°F is given in Table 6.

Figure 9-Vented Vapor Saturation Factor (Ks)

For refined petroleum stocks and crude oil stocks, the stock condensed vapor density, Wve, is lower than the stock liquid density, WL. If this information is not known, it can be esti mated from Equation 41, which was developed primarily for gasoline stocks:

Wve= 0.08 Mv (41)

where

Wve = stock condensed vapor density, in pounds per gallon,

Mv = stock vapor molecular weight, in pounds per pound-mole.

The constant, 0.08, in Equation 41 has units of poundmoles per gallon.


For single-componentpetrochemical stocks, the stock con densed vapor density is equal to the stock liquid density, WL• For selected petrochemical stocks, the stock liquid density at60°F is given in Table 7.

19.1.2.2.3 Working LossVariables

The working loss, Lw. is related in Equation 7 to the following variables:

a. Volume of displaced vapors, Q (expressed in terms of N,HLX, andD).

b. Stock vapor density, W¡;;

c. Product factor, Kp

d. Tumover (saturation) factor, KN.

e. Vent setting correction factor, KB•

The variables pertaining to stock vapor density, Wv. were discussed in 19.1.2.2.2.The additional working loss variables of stock annual net throughput, Q; working loss tumover fac tor, KN; working loss product factor, Kp; and vent setting cor rection factor, KB; are discussed in 19.1.2.2.3.1 through19.1.2.2.3.4.

19.1.2.2.3.1 Annual NetThroughput, Q

The annual net throughput, Q, as used in this publication, is the total volume of stock that is pumped into the tank in a year that results in an increase in the level of the stock liquid in the tank. If filling and withdrawal occur equally and simul taneously so that the liquid level does not change, the net throughput is zero. The annual net throughput is presented in Equation 7 as a function of the volume of the tank and the number of tumovers. The volume of the tank is expressed in terms of the tank diameter, D, and the stock maximum liquid height, HLX•

19.1.2.2.3.2 Turnover Factor, KN

For tanks where the annual net throughput, Q, is large, resulting in frequent tank tumovers (greater than 36 tumovers per year), the vented air-stock vapor mixture is not

saturated

=

D = tank diameter, in feet,

HLX = stock maximum liquid height, in feet.

In Equation 42, the constant, 5.614, has units of cubic feet perbarrel.

19.1.2.2.3.3 Product Factor, Kp

Figure 1Q-Working Loss Turnover Factor (KN)

with stock vapor. The working loss tumover factor, KN, is used to account for this non-saturation condition in the vented vapor. The tumover factor can be determined from Figure 10 or calcu1ated from Equations 8a and 8b:

180+NKN 6N (for N> 36) (8a)

(for N:s 36 (8b)

where

KN = working loss tumover factor (dimensionless),

N = stock tumover rate, in tumovers per year.

In Equation 8b, the constant, 180, has units of tumovers per year, and the constant, 6, is dimensionless.

The stock tumover rate, N, may be calculated from Equation42:

The working loss product factor, KFI accounts for the effect of different types of liquid stocks on evaporative loss during tank working. The use of this product factor applies only to working losses and should not be used for estimating stand ing storage los ses.

Product factors have been developed for multicomponent hydrocarbon liquid mixtures, including crude oil stocks and refined petro1eum stocks (such as gasolines and naphthas), as well as for sing1e-component petrochemical stocks.

Kp = 0.75 for crude oil stocks. (43a)

Kp = 1.00 for refined petro1eum stocks. (43b)

Kp = 1.00 for sing1e-component petro-barre1schemical stocks. (43c)

19.1.2.2.3.4 Vent Setting Correction Factor, Ka

Previous editions of 19.1 (i.e., the first and second editions of API Publication 2518) did not include a vent setting cor rection factor, KB, in the calculation of working losses. The method for estimating working loss in those editions assumed that the tank behaves as if free1y vented during the tank filling process. This assumption is reasonab1e for very 10w breather vent settings (such as the typical1eve1 of one-half ounce per square inch). As the breather vent settings increase, however, the free1y-vented assumption becomes increasing1y conservative (i.e., results in an overestimate ofworking loss).

The calcu1ation of the vent setting correction factor is performed in two steps. The first step is a check to determine whether the compression of the vapor space during filling, prior to opening of the vent, is sufficient to bring the concen tration of vapors in the head space aboye the saturation point.If the vapor concentration is shown to reach the saturation

where

N = 5.614 Q

(~) D2 HLX

N = stock tumover rate, in tumovers per year,

(42) point, it is assumed that condensation takes place. The amount of vapor reduction due to condensation is then calcu-1ated in accordance with the ideal gas 1aws, as formu1ated inEquation 15.

19.1.2.3 SUMMARY OF CALCULATION PROCEDURE

Q = stock annual net throughput (associated with increasing the stock liquid 1eve1in the tank), in barreIs per year,

Tab1es 2 and 3 summarize the equations and information necessary to estimate the total evaporative loss, Ly; from a fixed-roof tank, including the standing storage loss, Ls, and

Normal Gasoline Reformulated wlMTBE Oxygenated wlMTBE0.0 8.8 12.0

the working loss, Lw. The information in these tables is the same as that presented in 19.1.2.1 and 19.1.2.2, but without all of the important descriptive qualifiers presented in those sections. Therefore, questions about the information in Tables2 and 3 should be answered by referring to 19.1.2.1 and19.1.2.2 for more detailed information.

19.1.2.3.1 Speciation of Evaporative Losses

When the procedures in 19.1.2 are applied to a fixed-roof tank storing a multicomponent hydrocarbon stock, the result is an estimate of the total hydrocarbon emissions from the tank. The process of breaking down the total emissions of a mixture into its specific components is commonly referred to as speciation. Guidance for speciating total hydrocarbon emissions into the emissions of the individual components is provided in API's Manual of Petroleum Measurement Stan dards, Chapter 19.4, Recommended Practicefor Speciation of Evaporative Losses.

When speciated emissions are desired for only a portion of the components in a mixture, such as those deemed to be toxic, the calculation example of Chapter 19.4, First Edition,

Section 5, may be followed. The calculation steps are summarized in the footnote to Chapter 19.4, First Edition, Table 4. More detailed guidance for this procedure is found in Chapter19.4, First Edition, Section 7.2. This procedure requires the following information:

• total hydrocarbon emissions as estimated in accordance with 19.1.2,

• vapor molecular weight of the stock,

• true vapor pressure of the stock at the average liquid surface temperature,

• liquid molecular weight of the stock,

• molecular weight of each component to be speciated (for single components, liquid-phase and vapor-phase molecular weights are the same),

• true vapor pressure of each component to be speciated, at the average liquid surface temperature, and

• liquid weight fraction of each component to be speciated (i.e., the weight fraction of the component in theliquid mixture).

Table 9- Typical Concentrations of Selected Chemicals in Common Petroleum Products

GasolineJP-4

(Jet Naphtha)JetA

(Jet Kerosene)Diesel

(Distillate Fue1 Oil No.2)

Liquid Molecular Weight1 92 120 162 188

Component Typical Liquid Concentration, Weight Percent

n-Hexane 1.0 1.5 0.005 0.0001

Benzene 1.8 0.6 0.004 0.0008

Iso-octane2 4.0 0.0 0.0 0.0

To1uene 7.0 2.0 0.l33 0.032

Ethy1benzene 1.4 0.5 0.127 0.0l3

Xy1enes3 7.0 2.5 0.31 0.29

Cumene4 0.5 0.2 0.0 0.0

MTBE Note 5 0.0 0.0 0.0

1,2,4- Trimethy1benzene 2.5 0.0 0.0 1.0

Cyclohexane

Notes:

0.2 1.2 0.0 0.0

1. Liquid molecular weights from "Memorándum from Patrick B. Murphy, RadianJRTP to James F. Durham, EPA/CPB Conceming Petro-1eum Refinery Liquid HAP and Properties Data, August 10, 1993," as adopted in versions 3.1 and 4.0 ofEPA's TANKS software.2. Iso-octane is also known as 2,2,4 trimethy1pentane.3. The Chemical Database in EPA's TANKS software inc1udes m,o-Xy1enes. For convenience, use m- to represent all xy1enes.4. Cumene is also known as isopropy1benzene.5. MTBE concentrations vary significantly. EPA, in the Background Information Document for the Gasoline Distribution Industry (Stage 1) MACT Rule, suggests the following liquid concentrations:

MTBE %

If data are not available for a specific stock, the values given in Table 9 may be assumed for the common petroleum products shown.

19.1.2.4 SAMPLE PROBLEM

19.1.2.4.1 Problem

{since PVA < 0.1 psia; PE = ±O.03 pounds (0.5 oz) per square inch} (3b)

I1Tv= 0.72 (TMAX- TM/N) + 0.0280. 1 (25b)

(given)

Estimate the total annual evaporative loss, in pounds per year, given the following information:

A fixed-roof tank has the following characteristics:

a. A diameter of 100 feet.

b. A shell height of 40 feet.

c. A cone roof with roof slope not given.

d. A typical or average liquid level of 20 feet.

e. A maximum liquid level of 38 feet.

f. The tank is painted white, and the paint is in good condition.

g. The breather vent pressure setting is 0.03 pounds per square inch gauge and the breather vent vacuum setting is-0.03 pounds per square inch gauge.

The product stored in the tank has the following character

TM1N=45.1°F

a. = 0.17

I = 1502 Btu/ft/day

KE = 0.042

Hs=4Ofeet HL

=20feet HRO= e13)HR

(given)

(Table 5)

(given)

(4)

(given)

(given)

(16a)

(17a)

istics:

a. A stock of diesel fuel (distillate fuel oil no. 2).SR = 0.0625 feetlfoot (default per 19.1.2.2.2.1.1)

b. The Reid vapor pressure is not known.

c. The stock vapor and liquid composition are not given.

d. An annual net throughput of 3.0 million barreIs per year.

The ambient conditions are not known at the tank location, but the nearest city is Wichita, KS, for which the following values are given:

a. A daily maximum ambient temperature of 67.6°F (Table 4).

b. A daily minimum ambient temperature of 45.1 °F (Table 4).

c. A daily total solar insolation on a horizontal surface of1502 British thermal units per square foot day (Table 4).

d. An atmospheric pressure of 14.0 pounds per square inch absolute (EPA's TANKS software).

19.1.2.4.2 Solution

19.1.2.4.2.1 Standing Storage Loss, Ls

Calculate the standing storage loss, Ls, by following the steps in Table 2:

(2)

Rs= 50feet

HR =3.1 feet

HRO = 1.0 feet

Hvo = 21.0 feet

D = 100 feet

PVA = exp [A- (BITLA)]

A = 12.101 (dimensionless)

B = 8,907.0oR

TLA = TAA + 0.56 (6 x-1) + 0.0079 xl

TAA = (TAX+ TAN) 12

TAN = TM/N + 459.67

(given)

(given)

(5)

(29)

(Table 6)

(Table 6)

(24b)

(20)

(18)

(19)

KE = 0.001811Tv

PVA = 0.006 psia

Ks=0.99

Wv = MVPVA R TLA

(6)

19.1.2.4.2.3 Total Loss, Lr

Calculate the totalloss, Ly; from Equation 1:

Lr (pounds per year) = Ls (pounds per year)

+ Lw(pounds per year)

= 351 + 1,651

Lr = 2,002 pounds per year

(1)

Mv = 130 lb/lb mole (Table 6)

R = 10.731 psia ft3 / lb mole °R

Wv= 0.OOO14lb/ft3

Ls = 351 lb/yr

19.1.2.4.2.2 Working Loss, Lw

(Table 2) 19.1.3 Description of Fixed-RoofTanks19.1.3.1 GENERAL

This section describes evaporativeloss-related construction features of fixed-roof tanks. Figure 11 shows a typical fixed roof tank. Fixed-roof tanks are vessels that have a vertical cylindrical shell and a fixed roof. In addition to the shell and roof, the basic components and construction features include:

Calculate the working loss, Lw; by following the steps inTable 3:

(7)

a. Roof fittings that penetrate the fixed roof and serve operational functions.b. Shell and roof insulation on tanks that store stocks in a heated condition.

N = 5.614 Q

(~) D2 HLX

Q = 3,000,000 bbllyrD = 100 feetHLX=38 feet

N=56.4

KN= (180 +N) / (6N)

KN=0.70

(42)

(given) (given) (given)

(8b)

c. Shell and roof surface type and condition.

General types of these components, which are available in a range of commercial designs, are described in this section. Included in these descriptions are comments on the potential for evaporative loss, as well as some design and operational characteristics. Other factors, such as tank maintenance and safety, are important in designing and selecting tank equip ment, but are outside the scope of this publication.

19.1.3.2 FIXED-ROOFTANKS

The fixed-roof tank is the minimum accepted standard for the storage of volatile liquids. Large, modern fixed-rooftanks are of all-welded construction and are designed to be liquid

Kp=l (Table 3)

KB = 1 {since PB = ±O.03pounds (0.5 oz) per square inch} (9)

WV= 0.OOO14lb/ft3{from the Standing Storage Losscalculation}

Lw= 1,651lb/yr

and vapor tight. Some older fixed-roof tanks may be of riv eted or bolted construction. In this publication, it is assumed that the tank roof and shell are vapor tight. These are available in a range of sizes from 20 to 300 feet in diameter and up to65 feet in shell height. The fixed roof may be column-sup ported or self-supported, and may be cone-shaped, dome shaped, or flat. Some fixed-roof tanks incorporate an internal floating roof, but these types of storage tanks are not covered by this publication.

19.1.3.3 ROOF FITTINGS

Several roof fittings penetrate the tank roof to allow for

operational functions and are potential sources of evaporative loss. Other accessories that are used that do not penetrate the roof or shell are not potential sources of evaporative loss.

43SECTION 1-EvAPORATIVE t.oss FROM FIXED-RoOF TANKS

Roof fittings can be a source of evaporative loss when they are not sealed. The most common types of roof fittings used on fixed-roof tanks are described in 19.1.3.3.1 through19.1.3.3.4.

The evaporative loss contribution of properly sealed roof fittings is negligible in comparion to the standing loss and the working loss, and thus no roof fittings loss estimation proce dure is included in this publication.

19.1.3.3.1 Pressure-Vacuum Vents

Pressure-vacuum (PV) vents are mounted on the tank roof to provide sufficientventing capacity to protect the tank from the damaging effects of overpressure or overvacuum.

When a pressure is formed within the tank vapor space that exceeds the pressure set point, the PV vent opens to release vapors from the tank until the pressure is reduced below its set point. When a vacuum is formed within the tank vapor space that exceeds the vacuum set point, the PV vent opens to admit air into the tank until the vacuum is reduced below its set point.

API Bulletin 2521 [9] describes the use of PV vents on fixed-roof tanks and presents factors that should be consid ered in their selection and maintenance. API Standard 2000 [10] describes the sizing requirements for PV vents on fixed roof tanks and covers both normal and emergency venting conditions.

Bmatherwnt (open or PN typa)

Ga uge-hatc!1isample well

Roof manhole

Stabl" (Il<llllx>iling)stock liqwd --.

PV vents on atmospheric pressure fixed-roof tanks are usu ally set at 0.75 inches of water column, or approximately 0.5 ounce per square inch. The required normal pressure venting capacity or vacuum venting capacity should accommodate breathing and product movement up to the maximum safe working pressure or vacuum of the tank.

Open vents of the mushroom or return-bend type are not normally used on fíxed-roof tanks storing volatile liquids since they permit higher losses.

PV vents sbould receive regular inspection and maintenance, the frequency depending upon local conditions.

PV vents are sometimes equipped witb ftame arrestors. When a ftame arrestor is used, additional consideration must be given in sizing the PV vent to allow for the ftow restriction caused by the ftame arrestor. The use of a ftame arrestor also increases maintenance requirements, since the ftame arrestor must receive frequent inspections and cleaning to ensure blockage-free operation.

19.1.3.3.2 Gauge-Hatch/Sample Wells

Gauge-hatch/sample wells provide access for manually gauging the stock level in the tank and for taking thief sam pIes of the tank contents.

Gauge-hatch/sample wells consist of a pipe penetration on the tank roof that is equipped with a self-closing cover.A gas keted cover may be used to further reduce evaporative losses.

Figure 11-Typical Fixed-RoofTank

Gauge-hatch/samp1ewells are usually located by the gauger's p1atform,which is mounted at the top of the tank shell.

Some vapor loss may occur during manual gauging and stock sampling operations, during which time the gauge hatch/samp1e well cover is open. This loss can be mini mized by reducing the period of time that the cover is 1eft open.

19.1.3.3.3 Float Gauges

Float gauges are used to indicate the 1eve1of stock within the tank.

Float gauges consist of a float that rests on the liquid sur face and its connected to a liquid 1eve1indicator mounted on the exterior of the tank shell by a cable or tape that passes through a guide system. The cable or tape passes through the tank roof and is normally contained in a sealed conduit to eliminate evaporativeloss.

19.1.3.3.4 Roof Manholes

Roof manho1esare used to provide access to the interior of the tank for the purpose of construction or maintenance.

Roof manho1esnormal1yconsist of a circular opening in the tank roof with a peripheral vertical neck attached to the roof and a removab1ecover. The opening is sized to provide for the passage of personne1 and materials through the tank roof. The cover can rest directly on the neck, or a gasket can be used between the cover and the neck to reduce evaporative loss. Bo1tingthe cover to the neck further reduces evaporative loss.

19.1.3.4 INSULATION

Insu1ationcan be used on the tank shell and roof to reduce heat input or heat loss.

Some stocks must be stored in a heated condition to permit proper handling. Tanks for warm service may require insu-1atedshells and roofs, depending upon the local climatic conditions, stock properties, and required storage temperature.

Various types of insu1ation systems have been used including:

a. Prefabricated rigid panel insu1ation.b. Prefabricated fibrous b1anketinsu1ation.c. Sprayed-on po1yurethanefoam insulation.

Insu1ationsystems should be equipped with a suitab1eexte rior vapor barrier to reduce the ingress of moisture, which can result in a loss of insu1ationeffect as well as corrosion of the tank shell.

Insu1ationon the tank shell or roof can reduce the standing storage loss by reducing the ambient heat input or loss to the tank vapor space. The standing storage loss

estimation proce dure described in this publication does not include factors for

the use of insulation, and thus overpredicts the estimated loss for insulated fixed-roof tanks.

19.1.3.5 OUTSIDESURFACEOF THETANK

Painting the tank shell and roof is important in both reduc ing evaporative loss and preserving the tank. The use of a highly reflective surface, such as white paint, will result in a lower tank metal temperatures and lower heat input to the tank vapor space, thereby reducing the breathing loss. It is important to establish a tank paint inspection and mainte nance program to preserve the paint reflectance and eliminate tank exterior corrosion. Unpainted aluminum dome roofs also provide a highly reflective surface, while avoiding the mainte nance concems inherent to paint.

19.1.4 Details of Loss Analysis

19.1.4.1 INTRODUCTION

The first edition [11] of API Bulletin 2518 was issued in June 1962. That publication was the result of a compi1ation and study of extensive test data on evaporative loss from fixed-roof tanks storing gasoline and crude oil. A breathing loss corre1ation was developed from the test data that included stocks with a true vapor pressure between 1.5 and8.8 pounds per square inch abso1ute.Currently, vo1atileliquids with a true vapor pressure exceeding 1.5 pounds per square inch abso1uteare not stored in fixed-roof tanks in the U.S. The use of the breathing loss corre1ationpresented in the first edition of API Bulletin 2518 [11] for stocks with a true vapor 1essthan 1.5 pounds per square inch abso1utehas been found to a result in an over-prediction of the breathing loss. For this reason, recent studies have addressed the breathing loss by developing a database which could be used to provide a breathing loss estimation procedure that is suitab1efor use over the entire range of true vapor pressures for stocks that are stored in fixed-rooftanks.

During the period from 1977 through 1984, three specific testing programs invo1vedmeasurement of the breathing loss from fixed-rooftanks. In 1977,44 tests were performed on 21 fie1dtanks for the Westem Oil and Gas Association (WOGA) [12] that stored crude oils, distillates and fue1oils. In 1978, 15 tests were performed on six fie1dtanks for the U.S. Environ mental ProtectionAgency (EPA) [13] that stored isopropano1, ethano1,glacial acetic acid, formaldehyde, ethy1benzene,and cyclohexane. In 1984 and 1985, ten tests were performed on one test tank for API [14] that stored Fue1Oil No. 2.

The test methods utilized to perform these 69 tests were

similar for each of the three test programs. This test method invo1vedcollecting and measuring the vo1ume of air-vapor mixture that was emitted from the fixed-roof tank during its dai1y breathing cycle. In addition, the data included stock property data, tank construction data, meteorological data,


and tank operating data. Each test was of one-day duration, covering a single breathing cycle.

Although theAPI tests [14] were performed on a single 20- foot diameter test tank, the amount of information collected were extensive. The vertical temperature distribution inside the tank, extending from below the liquid 1eve1 upward through the vapor space to the tank roof, was continuous1y monitored during each test by a series of temperature sensors uniformly positioned on a vertical staff inside the test tank. These temperature measurements included the liquid bulk temperature, liquid surface temperature, vapor space temper ature, and metal temperatures on the tank roof and shell. This temperature data provided valuab1e insight into the convec tive mixing which occurs in the tank vapor space during the dai1y heating cycle.

To study the thermal response of a fixed-roof tank, a com puter program mode1 was developed [15] that simu1ated the dai1y heating cycle. A series of differential equations were solved by step-wise integration over the course of the dai1y heating cycle to evaluate the thermal response of each of the tank e1ements including the tank shell, roof, liquid surface, liquid bu1k, and vapor space. The computer program was used to develop a computer database that included the pre dicted breathing loss and tank thermal response for a total of561 sets of conditions that covered a wide range of tank construction, stock properties, and meteorological condi tions. When the thermal response and breathing loss pre dicted by the API computer mode1 were compared against the data collected in the API tests [14], excellent agreement was found [16].

Using the API computer database, several proposed loss equations were evaluated [17]. Based upon a comparison with the API computer database, a standing storage loss equa tion was se1ected. This loss equation is not a corre1ation of test data, as was the breathing loss equation in the first edition of API Bulletin 2518 [11], but rather is an equation resu1ting from a theoretical mode1 of the breathing loss process.

Section G of the Documentation File for API Manual ofPetroleum Measurement Standards, Chapter 19.1, contains a sensitivity analysis of the standing storage loss equation. This sensitivity analysis examined the effect on breathing loss of each important variable as it was independently varied over a range of conditions that included a base-case condition.

Section H of the Documentation File for API Manual ofPetroleum Measurement Standards, Chapter 19.1, contains a comparison of the standing storage loss equation with the WOGA [12], EPA [13], and API [14] test data. This compari son includes a comparison of the calcu1ated vapor space tem perature range, calculated vented gas vo1ume outflow, and calcu1ated daily standing storage loss with that measured in the tests. The API tests provided an extensive and accurate set of test data for comparison with the API standing storage loss equation. The average percent difference between the calcu-1ated and measured standing storage loss was 14.3 percent for

the API test data. The EPA and WOGA test data also confirmed the suitability of the standing storage loss equation.

19.1.4.2 LOSS MECHANISMS

19.1.4.2.1 General

Every liquid stock has a finite vapor pressure, dependent upon the surface temperature and composition of the liquid, that produces a tendency for the liquid to evaporate. Through evaporation, allliquids tend to establish an equilibrium con centration of vapors aboye the liquid surface, Under com p1ete1y static conditions, an equilibrium vapor concentration would be established, after which no further evaporation would occur. However, fixed-roof tanks are exposed to dynamic conditions that disturb this equilibrium, 1eading to additional evaporation. These dynamic conditions are respon sib1e for continued evaporation, resulting in stock loss and atmospheric emissions.

Evaporation is the natural process in which a liquid is con verted to a vapor. Evaporation loss occurs when the evapo rated vapor escapes to the atmosphere.

19.1.4.2.2 Evaporative Loss

The total evaporative loss from a fixed- roof tank is the sum of the standing storage los s and the working loss. Evaporative loss from fixed-roof tanks may be divided into two catego ries-standing storage loss and working loss.

19.1.4.2.2.1 Standing Storage Loss

Standing storage loss is the evaporative los s of stock vapor resu1ting from the thermal expansion and contraction of the tank air-vapor mixture resulting from the daily heating cycle. This loss is also referred to as the breathing loss and occurs without any change in liquid 1eve1in the tank.

19.1.4.2.2.2 Working Loss

Working loss is the evaporative loss of stock vapor result ing from a change in liquid 1eve1 in the tank, and includes both filling los s and emptying loss.

19.1.4.2.2.2.1 Filling Loss

Filling loss occurs during an increase in liquid 1eve1in the tank, when the air-vapor mixture in the tank vapor space is compres sed and causes the pressure in the tank to exceed the PV vent pressure setting, expelling vapors from the tank.

19.1.4.2.2.2.2 Emptying Loss

Loss of stock vapors from the tank does not occur during emptying, because the direction of flow through the vents is from outside to inside. The fresh air that is drawn into the tank induces additional evaporation of stock vapors. These

vapors are accounted for in the saturation levels assumed in the working loss tumover factor, KN, and the standing storage loss saturation factor, Ks. There is not, however, a separate contribution to stock vapor loss that takes place during emp tying of the tank.

19.1.4.2.3 Standing Storage Loss Mechanisms

Several mechanisms are involved in evaporative loss dur ing standing storage. The primary driving force for standing storage loss from a fixed-roof tank is the daily heating cycle, which causes the tank vapor space temperature to increase during daytime hours and decrease during nighttime hours. This heating causes the air-vapor mixture in the tank vapor space to expand and increase in pressure up to the PV vent pressure setting, at which time vapor is vented from the tank vapor space, resulting in evaporative loss. Following the max imum vapor space temperature, which normally occurs in the early aftemoon hours, cooling causes the air-vapor mixture in the tank vapor space to shrink and decrease in pressure. When the pressure falls below the PV vent vacuum setting, air is drawn into the tank vapor space which then becomes only partially saturated with stock vapor.

During daytime hours, the tank is exposed to ambient heat ing by both solar insolation and convective heat exchange with the ambient airo The tank roof is exposed to direct and diffuse solar insolation, as well as to convective heat exchange with the ambient airo The sunny-side of the tank shell is exposed to direct, diffuse, and ground-reflected solar insolation, as well as convective heat exchange with the ambi ent airo The shady-side of the tank shell is exposed to diffuse and ground-reflected solar insolation, as well as convective heat exchange with the ambient airo During the nighttime hours, the tank roof and shell exchange heat by convective heat transfer with the ambient air, there being no solar insola tion. This daily heating cycle causes the tank roof and shell to vary in temperature and exchange heat with the air-vapor mixture in the tank vapor space.

During the daily heating cycle, the air-vapor mixture in the tank vapor space exchanges heat with the tank roof interior surface, tank shell interior surface and the stock liquid sur face. This heat transfer causes convective motion of the air vapor mixture in the tank vapor space.

Also during the daytime when the tank vapor space is heated, some heat is transferred to the liquid surface causing it to increase in temperature, resulting in a higher stock vapor pressure at the liquid surface.

Evaporation occurs at the liquid surface as the stock tries to establish equilibrium conditions with the air-vapor mixture in the tank vapor space. Stock vapor evaporated from the liquid surface mixes with the air-vapor mixture and is convected upward toward the vent area by the convection currents that are induced during the daily heating cycle. Also, diffusion of

stock vapor occurs from the liquid surface to the tank vapor space.

As the liquid surface temperature increases during the daily heating cycle, additional stock evaporates in trying to establish saturated conditions aboye the liquid surface.

At the top of the tank vapor space, stock vapor mixes with the air which was drawn into the tank vapor space through the PV vent during the prior daily heating cycle. The combined effects of convection and diffusion affect the degree of satura tion that occurs at the top of the tank vapor space.

The combined effect of the aboye loss mechanisms results in movement of stock vapor from the liquid surface to the area below the PV vent, and eventually through the PV vent as the pressure exceeds the PV vent pressure set ting. The degree of saturation in the vented vapor depends upon the mass transfer rate of stock vapor from the liquid surface to the top of the tank vapor space by convection and diffusion. These mechanisms typically result in vapor strati fication, with the vapor concentration being lowest at the top of the tank vapor space and approaching saturation at the liquid surface.

19.1.4.2.4 Working Loss Mechanisms

Working los s is the combined effect of both filling loss and emptying loss.

19.1.4.2.4.1 Filling Loss Mechanisms

During tank filling, as the stock liquid level increases, the air-vapor mixture in the tank vapor space is compressed until its pressure reaches the PV vent pressure setting. At this con dition, the PV vent opens and air-vapor mixture is expelled from the tank vapor space to maintain the vapor space pres sure near the pressure relief setting. At this condition, a vol ume of liquid entering the tank displaces an essentially equal volume of air-vapor mixture from the tank vapor space.

As the tank filling process proceeds, the degree of satura tion in the vented vapor approaches saturation conditions. The degree of saturation in the vented vapor depends upon the time interval between the tank filling process and the prior tank emptying process, during which period of time the stock tried to establish equilibrium conditions in the tank vapor space.

The method of estimating working loss in earlier editions of 19.1 assumed that the tank behaves as if freely vented dur ing the tank filling process. In other words, the method assumed that the volume of air and vapor displaced from the tank is equal to the volume of liquid brought into the tank. This assumption is reasonable for very low breather vent set tings (such as the typicallevel of one-half ounce per square inch). As the breather vent settings increase, however, the freely-vented assumption may become conservative (i.e., result in an overestimate of working los s). When the breather vent pressure setting is sufficiently high, significant compres-

sion of the vapor space may occur before the vent opens. Vapors will begin to condense if compression of the vapor space continues after it has achieved saturated conditions, thereby reducing the volume of vapors released to the atmosphere. The vent setting correction factor, KB, has been added

Table 1Q-Annual Stock TurnoverRate (N) for 123 Test Tanks

N (Tumovers per Year) Number ofTests

<10 117

to the calculation of working loss in order to account for the 10 2condensation that may occur with higher vent settings.

2019.1.4.2.4.2 Emptying Loss Mechanisms

During tank emptying, as the stock liquid level decreases, the pressure of the air-vapor mixture in the tank vapor space decreases. When the pressure reaches the PV vent vacuum setting, air enters the tank vapor space through the PV vento During a rapid emptying process, the volume of stock removed from the tank is approximately equal to the volume of air entering the tank vapor space. The stock tries to estab lish equilibrium conditions with the entering air by evapora tion from the liquid surface. Stock evaporated from the liquid surface moves upward by convection and diffusion and mixes with the air which has entered the tank vapor space. The rate at which the stock vapor tends to saturate the entering air during tank emptying may reduce to some extent the volume of entering airoAs discussed in 19.1.4.2.3, these mechanisms tend to result in stratification of vapors in the tank vapor space. There is no loss of stock vapors from the tank during the emptying process, and subsequent loss of stock vapors are accounted for in the standing storage and filling loss mechanisms.

19.1.4.3 DATABASE FOR LOSS ANAL YSIS

19.1.4.3.1 Standing Storage Loss Data

The combined set of 69 tests included 10 from the API tests [14], 15 from the EPA tests [13] and 44 from the WOGA tests [12].

The API tests [14] were performed on a single 20-foot diameter test tank that stored Fuel Oil No. 2. The stock true vapor pressure ranged from 0.0054 to 0.014 pounds per square inch absolute, with a vapor molecular weight of 110 pounds per pound-mole. The tank vapor space outage was8.85 feet during the entire test series. Although the API test data was limited to a single tank with a constant liquid level, the extensive amount of tank temperature data and meteoro logical data permitted a rigorous comparison and validation of the API computer model.

The 15 EPA tests [13] were performed on six tanks, each containing a separate single component petrochemical that included isopropanol, ethanol, glacial acetic acid, ethylben zene, and cyclohexane.The tanks ranged in diameter from 54 to 120 feet, with the vapor space outage varying from 11.4 to

30 3

27.1 feet. A single temperature probe was used to measure the tank vapor space temperature during the daily heating cycle. Although the amount of tank vapor space temperature data in the EPA tests was not as extensive as it was in the API tests, it provided a valuable check on the vapor space temperature predicted, by the API computer model and the standing stor age loss equations. Since the stocks used in each tank in the EPA tests were single components petrochemicals, it was possible to accurately calculate the degree of saturation in the vented vapor during the daily heating cycle. This data pro vided a valuable basis for developing the vented vapor satura tion factor, Ks. The stock vapor pressure at the daily average liquid surface temperature in the EPA tests varied from 0.23 to 1.95 pounds per square inch absolute.

The 44 WOGA tests [12] were performed on 21 tanks that contained crude oils, distillates, and fuel oils. These tanks ranged in diameter from 50 to 175 feet, with vapor space out ages that ranged from 1.8 to 40.1 feet. The stock true vapor pressure at the daily average liquid surface temperature varied from 0.11 to 4.5 1 pounds per square inch absolute. Out of the44 WOGA tests, 12 were found suitable for use in developing the vented vapor saturation factor, Ks, and eight had sufficient detailed information to provide a comprehensive comparison with the standing storage loss equations. In the WOGA tests, the tank vapor space temperature was not measured, so it was not possible to compare the measured and predicted vapor space temperature range.

19.1.4.3.2 Working Loss Data

From a survey of petroleum companies and petroleum tank builders, working loss data on 123 tanks were compiled. The stock tumover rate, N, for the 123 tests is summarized in Table 10.

Data were collected on numerous items in each test in order to evaluate their effect on the working loss. Variables selected for potential correlation included: measured working loss, stock true vapor pressure (as determined from the stock Reid vapor pressure and the stock liquid bulk temperature), and the tumover rateo

19.1.4.4 DEVELOPMENT OF STANDING STORAGE LOSS EQUATION

19.1.4.4.1 General

The standing storage loss equation was developed from a physical model of the breathing loss process. This equation was derived from the ideal gas law and from the pressure, temperature, and volume conditions that exist in the vapor space of a fixed-roof tank containing a volatile liquid stock during the daily heating cycle. This derivation closely follows thatinAppendix 1 of API Bulletin 2513 [18]. SectionA ofthe Documentation File contains the derivation of the standing storage los s equation.

The standing storage loss equation requires an estimation of the vapor space temperature range, I1T v. A comprehensive heat transfer model of the daily heating cycle provided ananalytical equation was validated by the test data. Section eof the Documentation file contains the derivation of the vapor space temperature range equation.

It was necessary to incorporate a vented vapor saturation factor, Ks, to account for the nonsaturation conditions which are present in the vented air-vapor mixture. Again, a physical model was used to develop an analytical equation for thevented vapor saturation factor. Some of the parameters in the analytical equation, however, could not be directly calculated from the available test data, and thus the analytical expression was used only as a guide in developing a correlation equation for the vented vapor saturation factor. Section B of the Docu mentation File contains the development of the vented vapor saturation factor, Ks.

Previous editions of 19.1 (i.e., the first and second editions of API Publication 2518) presented the standing storage loss as shown in Equation 44, which is converted to the form of Equation 2 by substituting the right hand side of Equation 44 for the tank vapor space volume, Vv.

(44)

where Vvis calculated from Equation 45.

Tank Vapor Space Volume, Vv

(45)

19.1.4.4.2 Vapor Space Expansion Factor

The vapor space expansion factor, KE, is defined as the ratio of the volume of air-vapor mixture expelled during a daily breathing cycle to the volume of the tank vapor space.

A theoretical equation was developed for the vapor space expansion factor based upon a physical model of the breath ing process. This derivation closely followed that originally described in Appendix 1 of API Bulletin 2513 [18]. The equa-

tion derived from the ideal gas law and from the pressure, temperature, and volume conditions that exist in the vapor space of a fixed-roof tank containing a volatile liquid stock during the daily heating cycle.

At sufficiently high vent settings, the breather vent pressure setting range may become large enough to result in a negative calculated value of KE• This indicates that the vent settings are sufficiently high so as to not open during the daily breath ing cycle, and the standing storage loss should be taken as zero.

The simplified expressions of Equations 3a and 3b, for approximating the vapor space expansion factor for liquid stocks with true vapor pressure less than or equal to 0.1 psia, as sume typical breather vent settings of plus and minus one half ounce per square inch (i.e., ±O.03 psig) and thus a breather vent pressure setting range, ME, of 0.06 psig. At higher vent settings, this simplification becomes increasingly conservative (i.e., results in overestimating emissions). The absolute level of the standing storage loss for these low vapor pressure stocks, however, may be so small that further refine ment of the estimate is not warranted.

Section A of the Documentation File contains the development of the vapor space expansion factor, KE•

19.1.4.4.3 Vented Vapor Saturation Factor

The vented vapor saturation factor, Ks, is defined as the ratio of the daily average stock vapor concentration in the vented vapor to the daily average saturated stock vapor concentration. When Ks = 1, the vented gas is completely saturated; when Ks = O, the vented gas contains no stock vapor.

Using a theoretical model for the mass transfer process of stock vapor from the liquid surface to the PV vent during the daily breathing cycle, a theoretical equation was developed. This equation contains the pertinent parameters that affect the vented vapor saturation factor, Ks. The equation indicates thatKs tends toward 1 as the vapor space outage, H va, tendstoward O. It also indicates that Ks tends toward O as the stock vapor pressure at the daily average liquid surface tempera ture, PVA, tends toward atmospheric pressure, PA• The equa tion contains an overall mass transfer coefficient for the transfer of stock vapor from the liquid surface to the PV vent. Insufficient information was available to evaluate the overall mass transfer coefficient, and thus the theoretical equation provided only a guide to show the dependency of Ks on PVA,

Hva and other parameters.Although it may be possible to develop a more complete

theoretical equation for the vented vapor saturation factor, Ks, it was decided instead to develop a correlation based onactual test data. However, the simplified theoretical equation was used as a guide in selecting the analytical form for the correlation equation and in selecting the parameters to include in the correlation.

The API test data [14], EPA test data [13], and WOGA test data [12] were used to develop the correlation for the vented vapor saturation factor, Ks.

The vented vapor saturation factor was calculated for all ten of the API tests [14]. The vented vapor saturation factor for the API test data was close to one, with an average value for the ten tests of 0.964.

For the 15 EPA tests [13], 12 were found suitable for calcu lated a vented vapor saturation factor. Since the daily average liquid surface temperature, TLA, was not measured during EPA tests, Equation 22 in 19.1.2.2.2.5 was used to estimate the daily average liquid surface temperature. This tempera ture was used for determining the stock vapor pressure at the daily average liquid surface temperature, PVA• For the EPA tests, the vented vapor saturation factor varied from 0.18 to0.93, depending upon the stock vapor pressure at the daily average liquid surface temperature, PVA, and vapor space out age,Hva·

For the 44 WOGA tests [12],21 were found suitable forcalculating a vented vapor saturation factor. Again, since the daily average liquid surface temperature, TLA, was not mea sured during the WOGA tests, Equation 22 in 19.1.2.2.2.5 was used to estimate the daily average liquid surface tempera ture. For the WOGA tests, the vented vapor saturation factor varied from 0.21 to 0.96, depending upon the stock vapor pressure at the daily average liquid surface temperature, PVA, and the vapor space outage, H va.

A total of 34 data points were selected to develop the vented vapor saturation factor correlation from the combined set of API, EPA, and WOGA test data. The resulting correla tion was in agreement with the theoretical analysis in that it showed the same dependency of Ks on PVA and Hva.

Section B of the Documentation File contains both the development of the theoretical equation and the correlation for the vented vapor saturation,Ks.

19.1.4.4.4 VaporSpaceTemperature Range

The daily vapor space temperature range, I1T v. is defined as the difference between the daily maximum vapor space tem perature, Tvx, and the daily minimum vapor space tempera ture, TVN•

A heat transfer model was developed that described the heat transfer processes which occurred during the daily heating cycle. The model was based upon the following assumptions:

a. The gas space is fully mixed (i.e., it is at a uniform temperature at any given time during the daily heating cycle).b. The liquid remains at a constant temperature during the daily heating cycle.c. The tank wall in the gas space can be treated as three

sepa rate elements: (1) the roof; (2) the half of the tank shell facing away from the sun; and (3) the half of the tank shell facing the

sun. Each tank wall element may be characterized by a single temperature, which varies during the daily heating cycle.

d. The effects of rain and snow precipitation are not included in the model.

e. The heat capacity terms in the energy balance equations can be neglected in comparison to the other heat transfer terms.

Using these assumptions, heat balance differential equa tions were developed for each of the tank wall elements and the gas space. These ordinary differential equations were essentially the same as those used in the API computer model [15], where they were there solved by step-wise numerical integration. Assumption e allowed the differential equations to be reduced to a set of four simultaneous algebraic equa tions, which could be solved for the temperature of the gas space.

The wall elements were assumed to exchange heat on both their inside and outside surfaces. The inside of each element was assumed to exchange heat with the vapor space gas by natural convection heat transfer. The outside of each element was assumed to exchange heat with the ambient air by con vection and receive solar insolation. Certain typical solar insolation parameters were used (see Section D of the docu mentation File for the development of the solar insolation parameters) to simplify the vapor space temperature range equation. A sensitivity analysis indicated the vapor space temperature range depended little upon the ratio of the out side to inside convection heat transfer coefficients, and an average value was selected for these heat transfer coefficients. The resulting equation was further simplified to the case where the ratio of the tank vapor space outage, Hva, to tank diameter, D, is equal to 1.0.

The simplifiedheat transfer model was compared [17] with the 561 sets of data in the API computer database [19] and found to result in an average difference of about 4 percent.

Section C of the Documentation File contains the development of the vapor space temperature range, I1T V'

Section H of the Documentation File contains a compari son of the measured and calculated vapor space temperature range for the API, EPA, and WOGA test data.

19.1.4.4.5 Surface Solar Absorptance

The solar absorptance, 0., is defined as the fraction of the solar insolation absorbed by a surface.

The exterior surface of fixed-roof tanks are normally coated with a paint to reduce corrosion and reflect solar insolation. A wide range of paint colors have been used, sometimes with a different color on the tank roof than on the tank shell.

The absorptance of tank surfaces depends upon the tank color, surface type, and surface condition. Newly painted

sur faces, or surfaces in a good condition, will have a lower solar

absorptance than weathered painted surfaces or surfaces in poor condition.

At the time that the first edition [11] of API Bulletin 2518 was published, the importance of surface absorptance on breathing los s was recognized. A surface with a low absorp tance, such as white paint, was known to affect the breathing loss in two significant ways:

a. It reduces the transfer of heat to and from the tank vapor space and therefore reduces the volume of breathing loss.

b. It reduces the transfer of heat to the liquid bulk and there fore reduces the breathing loss by lowering the stock vapor pressure.

During the development of the first edition [11] of API Bul letin 2518, extensive work was directed at gathering solar absorptance data on paints. Discussions were held and correspondence was exchanged with paint chemists and the staff of one large paint manufacturero As a result of this work, a set of point factors, listed in Table 2 in the first edition [11] of API Bulletin 2518, was developed. These paint factors are not suit able for use in conjunction with the current standing storage loss equation, and had to be converted to values of solar absorptance. Figure IV-3 in the first edition [11] of API Bulle tin 2518 provided a relationship between the paint factor and solar absorptance. This figure was used to convert the paint factors into the solar absorptance values that appear in Table 5.

Section C of the Documentation File contains the develop ment of Equation 22, which is used to determine the tank sur face solar absorptance, 0., when the tank roof and shell are painted different colors.

Section E of the Documentation File contains the develop ment of the solar absorptance, 0., values that are listed in Table 5.

19.1.4.4.6 Liquid Surface Temperature

The standing storage breathing loss equations require determining the stock vapor pressure at the daily maximumliquid surface temperature, Tv:t.he daily average liquid surface temperature, TLA; and the daily minimum surface temperature, TLN.

A theoretical equation was developed for estimating these liquid surface temperatures that is based upon a heat transfer analysis of the liquid surface during the daily heating cycle. The resulting equations require input of the liquid bulk tem perature, TB•

The liquid bulk temperature, TB, is the daily average temperature of the liquid stock in the storage tank. This informa tion is usually available from tank gaging records or other tank operating records. If the liquid buIk temperature is not available, it may be estimated from the daily average ambient temperature, TAA, and the tank paint solar absorptance, 0., by

the relationship described in Figure IV-2 in the first edition [11] of API Bulletin 2518. Equation 21 in 19.1.2.2.2.4 is a linear fit of the data presented in Figure IV-2 from the first edition of API Bulletin 2518 [11], with the assumption that the liquid bulk temperature in a white tank is the same as the average ambient temperature, TAA•

Section F of the Documentation File contains the development of the liquid surface temperature equations.

19.1.4.5 DEVELOPMENT OFWORKING LOSS EQUATION

19.1.4.5.1 General

The working loss equation which appears in this publica tion is essentially the same as that which appeared in the first edition [11] of API Bulletin 2518. The equation which appeared in the first edition of API Bulletin 2518 was con verted from working los s units of barreIs per year into Equa tion 7 in 19.1.2.1.3 which expresses working loss units in pounds per year. It should also be noted that the formula was originally given in Appendix IIof API Bulletin 2513 [18].

Of the test data assembled on 123 working tanks, only six tanks exceeded ten turnovers per year. The remaining 117 tanks had less than 10 tumovers per year. Because so much of the test data available had a very low tumover rate, the data were analyzed using the equation given in Appendix IIof API Bulletin 2513 [18], which incorporates the turnover factor,KN, as a multiplier. When KN = 1, the equation represents theloss resulting from the displacement of a volume of saturated air-vapor mixture by an equal volume of liquid pumped into the tank.

Previous editions of 19.1 (i.e., the first and second editions of API Publication 2518) presented the working loss as shown in Equation 46. This is achieved by substituting the tank maximum liquid volume, VLX, for the corresponding terms in Equation 7, and then substituting the stock annualnet throughput, Q,for N and VLX. Expressing the stock annualnet throughput in barreIs per year requires that it be multi plied by the conversion factor, 5.614 cubic feet per barrel. Substituting for the stock vapor density, Wv. as shown in Equation 6, and selecting 63°F (523°R) as a typical value for the liquid surface temperature, TLA, allows Wv to be expressed as (0.0001781 Mv PVA). Combining this coefficient with the throughput conversion factor of 5.614 gives the coef ficient of 0.0010 used in previous editions. The working loss calculation shown in Equation 46 does not contain a vent set ting correction factor, KB, because previous editions of 19.1 conservatively ignored any condensation of vapors that may occur prior to the opening of the pressure relief vento

(46)

where

Q = stock annual net throughput (associated with increasing the stock liquid level in the tank) barreIs per year,

= (N VLX) / 5.614 where the constant 5.614 has units of cubic feet per barrel,

VLX = tank maximum liquid volume (cubic feet),

= HLX(rrJ4) D2.

over rates (exceeding 36 tumovers per year). This equation results in a value of KN = 0.74 at one turnover per week and KN = 0.25 at one turnover per day.

Section J of the Documentation File contains the development of the tumover factor, KN.

19.1.4.5.3 Product Factor

The working loss product factor, Kp, accounts for the effect of different types of liquid stocks on evaporative loss during tank working. The use of this product factor applies only to

The constant, 0.0010, in Equation 46 has units of pound moles per (pounds per square inch absolute) barrel.

Section I of the Documentation File contains a development of the working loss equation.

19.1.4.5.2 Turnover Factor

The turnover factor, KN, is defined as the fraction of satura tion in the vented vapor during working loss. When KN = 1, the vented vapor is saturated with stock vapor; when KN = O,the vented vapor contains no stock vapor.

For stock turnover rates, N, up to 30 turnovers per year, the available test data substantiated a value of KN = 1. No testdata was available for tumover rates greater than 30 turnovers per year. Based upon a suggested relationship between the working KN, and the stock tumover rate, N, which was pub lishedin theAPl Proceedings, V.32,Part l, 1952, pp. 212-281 [20]. Equation 39 in 19.1.2.2.3.2was developed for high tum-

working loss and should not be used when estimating standing storage loss.

The product factor, Kp, was included in the working loss equation to account for the effects of different types of liquid stocks on evaporative loss. These effects (such as weathering) are in addition to those accounted for by considering differ ences in stock true vapor pressure and vapor molecular weight.

In the first edition [11] of APl Bulletin 2518, a productfac tor, Kp, of 0.75 was selected for crude oil stocks. The avail able test data on crude oil working loss were found to be scattered and not sufficiently accurate to permit a formal cor relation. However, a review of the scattered data, as well as other considerations, supported a product factor of 0.75 for crude oil.

Section K of the Documentation File presents additional information on the development of the product factor, Kp

APPENDIX A-DOCUMENTATION RECORDS

The docurnentation records are rnaintained at American Petroleum Institute, MeasurernentCoordination Department, 1220 L Street, Northwest, Washington, D.C. 20005.

The records are available for inspection at the aboye address. Copies of sorne of the sections rnay be obtained frorn API on request for a copying

fee.

Table A-1-Contents of Documentation Records

Section Description

Introduction

Standing Storage LossA Development ofVapor Space Expansion Factor, KE

B Development ofVented Vapor Saturation Factor, Ks

C Development ofVapor Space Temperature Range, I1TvD Development of Solar Isolation Parameters

E Development of Surface Solar Absorptance, a

F Development of Liquid Surface Temperature Equations

G SensitivityAnalysis of Standing Storage Loss Equation

H Comparison of Standing Storage Loss Equation withTest Data

Working Loss

I Development ofWorking Loss Equation

J Development ofTurnover Factor, KN

K Development of Product Factor, Kp

L Comparison ofWorking Loss Equation with Test Data

53

APPENDIX 8-METRIC UNITS

8.1 GeneralTo convert the inch pound units employed in the text to equivalent SI units of the Intema

tional System of Units, the guidelines of the API MPMS, Chapter 15, shall be followed. The unit of length is either the kilometer, designated km, or the meter, designated m. The unit of mass is the kilogram, designated kg. The unit of volume is the cubic meter, designated m3. The unit of time is the year, designated yr. The unit of temperature is the degree Celsius, des ignated "C, or the kelvin, designated K. The unit of heat energy is the joule, designated J.

8.2 PressureThe unit of pressure is the kilopascal, designated kPa.

55

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