Report of the Committee on Electrical Equipment in Chemical Atmospheres

Richard Y. LeV'me, Chairma~i Stamford, CT

Mark C.Ode, Secretary National Fire Protection Association

(Nonvoting)

Alonza W. Ballard, Crouse-Hinds ECM Rep. National Electrical Manufacturers Assoc.

Albert A. Bardms, Underwriters Laboratories Inc. Michael K. Baueom, BEBCO Industries, Inc. Carol M. Boring, US Dept. of Labor David H. Byford, Unocal Corp.

Rep. American Petroleum Institute W'dliam G. Lawrence, Factory Mutual Research Corp. Ernest C. Magison, Honeywell Inc.

Rep. Instrument Society of America Richard C. Masek, Bailey Controls Robert E. McI~rmey, City of Tacoma, WA, Dept. of Public Utilities Charles R. Ih'asso, Industrial Risk Insurers Milton H. Ramsey, Chevron USA Inc. " '

Rep. Institute of Electrical & Electronics Engineers, Inc. John E. Rogerson, Cedar Lane Farm, OH R. F. Schwab, Allied-Signal Inc. George H. St. Onge, Bernardsville, NJ Daniel E. Vanover, United.States Testing Co., Inc. David Weehsler, Union Carbide Corp.

Rep. Chemical Manufacturers Assoc.

Alternates

Edward M. Briesch, Underwriters Labo?atories Inc. (Alt. to A. A. Bartkus)

James A. Robertson, Dow Chemical Co., USA Rep. Institute of Electrical & Electronics Engineers, Inc.

(Alt. to M. H. Ramsey)

Staff Liaison: Mark C. Ode

This list represents the membership at the time the Com- mittee was balloted on the text of this edition. Since that time, changes in the membershi p may have occured.

.~ The Report of the Committee on Electrical Equipment in

Chemical Atmospheres is presented for adoption. - -

This Report was prepared by the Technical Committee on Electrical Eqmpment in Chemical Atmospheres and proposes for adoption a revision to NFPA 497A, Recommended Prac'dce on Clas- sification of Class I Hazardous Locations in Chemical Plants. NFPA 497A is published in Volume 11 of the 1990 National Fire Codes and" in separate pamphlet form.

This Report has been submitted to letter ballot of the Techni- cal Committee on Electrical Eqhipment in Chemical Atmospheres which consists of 17 voting members; 1 ballot was not returned (Mr. Baucom). The results of the balloting can be found in the report.

32

NFPA 497A

(Log # 3) 497A- 1 - (2-3.2.1): Accept SUBMrFrER: Yonggang Chen, Worcester, MA RECOMMENDATION: ~rhe last sentence "which also enhances dis-

~ ersion" should.be deleted• UBSTANTIATION: For mass diffusion process, mass diffusion rate

m' should directively proportional m the concentration (density) gradient (2Ci/2X). The code states that When the density of the mixture approaches that of air, it enhances the dispersion, this is contrary to the theory. COMMITrEE ACTION: AccepL VOTE ON COMMITTEE ACTION: 16 affirmative, 1 negative. EXPLANATION OF VOTE: St. Onge:

"Article 2-3.2.1 "Diffusion" and "dispersion" are two different con- ditions. Paragraph 2-3.2.1 needs to be read in conjunction with the last sentence of 2.3.2. Paragraph 2-3.2.1 uses "dispersion" to convey mixture spreading is enhanced in contrast with he~tvier-than-air gas of 2.3.2.

(Log # 4) 497A- 2 - (3-3.2.1 (0): Accept in Principle SUBMrrTER: Carl C. Koslowski, Warren, MA RECOMMENDATION: Add new text:

(0 Are pressure relief valves located within the process equip- ment? SUBSTANTIATION: In the event that aprocess failure produces high pressures, a significant discharge of flammable vapors rfiay result. The large quantity of turbulent vapors will quickly fo~'n a flammable mixture. Whenever pressure relief valves are present, consideratiori must be given to escaping vapors . . COMMITTEE ACTION: Accept in Principle. COMMrr rEE STATEMENT: Change to ' (I) Are.pressure relief valve discharges located within the area?" VOTE ON COMMITI'EE ACTION: Unanimous.

(Log # ~) 497A- 3 - (Chapter 3, Section 3-4): Reject SUBMITI'ER: David N. Bishop, New Orleans, LA RECOMMENDATION: Following the pa.ragra~h "Figure 3-4.9 shows.., flammable liquid. (From API RP500A.) ', Addthe following underlined words inside the parentheses: (From API RP500A, applicable to those locations in which

petroleum gases and volatile flammable liquids are processed~ stored; or loadedp unloaded r or otherwisehandled in petroleum refineries.)

NFPA 497A

SUBSTANTIATION: The American Petroleum Institute has three separate publications dealing with the classification of locations for electricaI installations: RP500A, for refineries; RP500B, for produc- ing and drilling facilities; and RPS00C for pipeline facilities. The referenced figures are applicable ONLYto refineries. The 497A publication as now worded causes confusion to some users. For example, API RP500B must be used for classifying offshore facilities in the OCS area as specified by the Minerals Management Service (MMS), Department of the Interior. I see no need to add the note each time RP500A is cited; once should suffice. COMMITTEE ACTION: Reject. COMMITTEE STATF_aMENT: Figtire and index have been revised and no longer show API reference. VOTE ON COMMITrEE ACTION: Unanimous.

(Log # 1) 497A- 4 - (Figures 3-4.13, 3-4.15 through 3-4.20, 3-4.22, 3-4.26, 3-4.30 through 3-4.32): Accept. SUBMITrER: RichardK. Kaminski, Pittsburgh, PA RECOMMENDATION: Review figures for dimensions and radii:

Reviek, Figures 3-4.13, 3-4.15, 3-4.16, 3-4.17, 3-4.18, 3-4.19, 3-4.20, 3- 4.22,'3-4.26, 3-4.30, 3-4.31, 3-4.32. , . SUBSTANTIATION: Figures need review of dimensioning and notes. Arrowhead corrections are needed. Div. 1 should be added to some Div. 2 areas. The following marked up figures should be

• self explanatory. " . COMMITTEE ACTION: Accept. complete revision of drawings.

COMMITrEE ACTION: VOTE ON Ufianimous. EXPLANATION OF VOTE: Prasso.

"Figure 3-4.21(a) The radius shown on the right side should be 3 feet as marked on the drawing.

Figure 3-4.21 and Figure 3-4.2!(a) the size/pressure/flow box should be removed from this sheet.

Figure 3-4.30 Adding "Division 1," above the 5'R at the three pic- tures, left-hand side, would clarify where those ~'~-ows point.

St Onge. "Figure 4.3.4 "Marine Terminal Ha~ndling Hammable Liquids" "

should be credited to API Recommended practice 500A which is its original source."

/

I

33

NFPA 497A NFPA 497A

F3' R

0 o0o ; _ .,

Below grocle locat ion such as o sump or t r e n .

Figure 3-4.1 Leakage Source Located Outdoors, at Grade.

sour~oe/~~ 3' R

YJ~/, _L ~///////// ~."

I ~ I= IO 'R =i

~Be low grade locat ion such as 'o sump or t r ench ,

Figure 3-4.2 Leakage Source Located Outdoors, Above Grade.

MATERIAL. Flammable LiQuid SMALL/ LARGE/

LOW MODERATE HIGH

PROCESS EOUIP. ~ SIZE

PRESSURE ~

FLOWRATE ~

~I Division i

~ 2 ~ Divis ion 2

34

NFPA 497A 'NFPA 497A

Source 5' R

Grade

"~ . . . . .. ~: 25' R -I, " ~X Below g r a d e location s u c h as a s, jmp o r t r e n c h .

,

Figure 3-4;3 Leakage Source Locozed Indoors, at Floor Level. Adequate V e n t l l o ~ l o n Is P r o v i d e d .

S o u r c e - ~ , / / / / / / / / / / . _ 1 - 5 ' R

2Z 7 r 2 5 ' R 7 ~ ,

Below grade l o c a t i o n s u c h as a sump o r t r e n c h .

~f

Figure 3-4.4 Leakage Source Located Indoors, Above Floor Level. Adequate Ventllatlon is Provlded.

~AATERIAL. Flammable Liquid

SMALL/ LOW MODERATE

PROCESS EOUIP. 7 7 SIZE

PRESSURE ~

FLOWRATE 7 V

LARGE/ HIGH D i v i s i o n I

D l v l s l o n 2

35

NFPA 497A

oraclej

NFPA 497A

P i e r c e d ~ u n D l e r c e d

wo 1= ~- Below grade locot,on 25' Max R 25' R s u c h ~s e sump or-

tx'ench.

Figure 3-4.5 Leakage Source Located indoors, a t Floor Level, Adjacent to 0Dening In Ex te r i o r Wall. Adequate Vent i lat ion Is Provided.

Grode~ ~,°ll~/i////~ " . . , wall

o

' ! ~ox!_ Less than J L ~ i ~ 1 ~ 3' ' " outslcle 25' R I I • 25' R , ~ ~ "

8eL" 0 oo. ,oco,,oo .oc. o , o , o . o Division I or Division 2 portion of building.

Figure 3-4.6 Leakage Source Located indoors, at. Floor ° Level , Adjacent to 0penlng In Ex te r i o r Wall.

Adequate vent i la t ion is NOT Provided.

Note: If building Ts small comDared to size of ecluiDment and leakage can fill the building, the entire building inter ior is classified Division I.

MATERIAL: Flammable Liquid.

SMALL/! LOW

PROCESS EQUIP. SIZE

PRESSURE

FLOWRATE

LARGE/ ~OOERATE H,C.

7 ~ Division,

7 ~ Division 2 7

36

NFPA 497A NFPA 497A

--15' R

• soo o e

C~o~e 7 ,

4 f

Below grade locat ion such //r, as o sump or t rench . _ _ _ /

Figure 3-4.7 Leakage Source Located Outdoors, At Grade.

Figure 3-4.8

S o u r c e

- - 1 5 ' R

Z Below grade Iocot lon such as e sump or t r ench .

Leakage Source Located Outdoors, Above Grade.

MATERIAL: Flammable Liquid, Liquefied Flommable Gos Compressed Flammable Gas, ancl Cryogenic l.:i(:lufd

SMALL/ LOW

PROCESS EQLIIP. SIZE

PRESSURE

FLOWRATE

MOOERATE

V

J V

ILARGE/ HIGH

Y

Division I

Division 2

37

NFPA 497A NFPA 497A

, 25' Source -- -k ~

Below g rade loca t ion suc J- :q aS a sump or t r e n c h • IO0'

Figure 3-4.9 Leakage Source Located Outdoors, At Grade.

Source

T i 25'

T 25'

Below grade location such~ " ~ as a sump or trencln.

- - I 50'

,

I00' I

Figure 3-4.10 Leakage Source Located Outdoors, Above Grade,

MATERIAL: Flammable Liquid

PROCESS EQUIP. SIZE

PRESSURE

FLOWRATE

SMALL/ LOW MODERATE

J

LARGE/ HIGH

,/

,/

V

Division I

Division 2

Additional division 2 location ext ra pre- caution where large release of volat i le products may.occur.

'- 38

NFPA 497A NFPA 497A

Pierced I--- 0 R . , • ,WOII ~ / / ~ . / . , ~---S ou,'r ~e

2' / . 25' ~ / / / / / / ~ UnpierceO L I " / / / / / / / / / 6 ~ Wa, , Or°de 7 ~ ' ~ , ~ \ ~ / / / / / / / / ~

~*""L l~'so' No,e , , '

W _l Below grade locctlon such • I~ -I as a sump or trench.

Notes: I00'

I) Apply horlzontel dlstances oF 50 Feet From the source o£ vapor or 10 Feet beyond the per}.meter o£ the bul ldtng, whichever Is g rea te r , exoep~ t h a t beyond unpterced v a p o r t l g h t wal ls the area Is nonclassl£1ed.

Figure 3-4.11 Lec]koge Source Located Indoors, Adjacent to Opening in Exterior Wolf. Adequate Ventilation Is NOT Provided.

• F i g u r e 3-4.12

S o u r ~ - ~

Pierced

I " 50"

~ noiercecl Well

• ~1~__ Below g r a d e l o c o t l o n such as a sump o r t rench .

Leakage Source Located Indoors, ' Adjacent to Opening in Exterior Wall. Adequate Ventilation Is Provided.

MATERIAL" Flammable Liquid

~SMALL/ LOW

PROCESS EQUIP. SIZE

PRESSURE

FLOWRATE

MODERATE

7

LARGE/ HIOH

7

J

Division I

Division 2

Additional division , 2 location ex t ra pre- caution where large release o f volatile procucts may occur.

39

NFPA 497A NFPA 497A

'Plpewc w i thoL m e t e r , gaske" flange

Gr-o

MATERI . . . . . . . . . . . . . . . . . . . ~__ _

kOI MOOERATE H ~

~q0c~ss Eo~P. 4 # ~zE

p~ssuns # ¢

Solld d e c k e x c h a n g e c level

Typ. s u p p o c t column

3' R a b o v e pumps, e t c .

cotlom such as tch,

Division I ~'7~ Division 2

Figure 3-4.13 Multiple Leakage Sources, Both At and

Above Grade in Outdoor Process Area.

- °

40

NFPA 497A NFPA 497A

MATERIAL: F lammable L[qul 'd SMALL/ L ~ E A

• LOll UOOEPJI, TEi HIGH

~oa:ss Eo.p. 4 s~zE

FLOWRATIr V / ~/.

' P r o c e s s ~ - I ~ Process

Column I I t ~' I I °°'°=~

;/ ~/'/J~, 2 5 :

• : -~ ~ / / 4 ~ 2 Y / / f _ / / Z / / ~ ~ ~ (souroe,

I / / . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~/'/~. so l id f l o o r

. . . . . . . J L 2 " ~ / / . / / / / / / / / / / / / / / x / / / / / / / / / / / / / ur aae 7 ~ r / / / Y / / r / / / ~ o.o o o o.o t,p'///~//,4///A ~ \ \ \ \ \ ~

50' 50' a l ley '~-- S o u r c e s

Below grade locatlon s u c h os e sump o r t r e n c h ,

D l v l s i o n l

D tv ls lon 2

~ . AdditionaldivlsiOn 2 area where release

. may be large

Figure ~,-4.14 Multiple Leakage Sources, Both At and Above Grade, in Outdoor Process Area.

41

N F P A 497A N F P A 497A

Division 2. = ~ ~/ 5' R from "/~/ ~/ v e n t s (typ) N

Solid f l o o r wlth ---~ I] " IJ opening for vessel / -z '8'

"~, ~ .r,.,.,,~ k r~ / / / / ,1 ~ ' f / 2 7 / , 1 1 A

dump took N~ 11 , / / ~ . l l / / / , / / / ,

3'R croun~ p typi o

Division I, 3' R from

_ vents (typ) ' r

3' R orouncl vesse l oncl II leok sources such

~=~/.. ,.,~Grctlng floor wlth I~ ll°Pe~ng for vesse,.

~,~/////~18 Y~ Typlccl support column

Below grcde locotlon such os c sump or trench

Figure 3-4.15 Multiple Leakage Sources, Both At and Above Grade, in Outdoor Process Area.

42

NFPA 497A NFPA 497A

Division 2, 5"R from vents (typ)

Outside,wall SolIcl floor--, wlth openin X~X for vessel

• Division 2 . - - ,3' R from vents

OuTdoor ~ ) Emergency dump TO~K

Below grote I oco t i on~ such cs c sump or t rench.

. i .

I< =I 25:

5' R around - I leak sources I SUCh as man- I holes, valves, I etc. •

on I, 3' R f rom vent (typ)

Outside wall

--Grating floor with openIng for vessel.

-- Division 2, 5 'R around pump. and tank

. ~ G'r- ode

3' R around tank a t locat ion shown

Figure 5-4.16 Multiple Leakage Sources, Both At and Above Floor Level, Located Indoors. Adequate

Ventilation Is Provided,

MATERIAL: Flammable Liquid

SMALL/! LOW MODERATE

PROCESS EQUIP. ~ SlZE

PRESSURE ~ FLOWRATE ~ 7

LARGE/ HiGH

~ ] Div is ion

~7~'~. Division 2

43 °

NFPA 497A NFPA 497A

Division I

5 ' R "

//// ~ ~ / ~ ~ Division 2. I0' R

Vent

-- Inert gcs __ / , blonget In

. o r o~,-" " I K / I

~ . Division I Division 2

t

I

MATERIAL: Soli'ds Wet with Flammable Liquid

Figure 3-4.17 Totally Enclosed Product Dryer • Located in Adequately Ventilated Building:

44

NFPA 497A NFPA 497A

,

s

~--Vent t o solvent recovery

~ - Hoocl - 'up' p o s i t i o n

L . . .~J

F rl 25'R

3'

Divisior~ ~7~ Division 2

MATERIAL: Solids Wet with Flammable Liquid

D

Figure 3-4.18 Plate and Frame Filter Press Provided with Adequate Ventilation.

45

NFPA 497A ,NFPA 497A

Tcnk w i t h i n d i k e _- = Tank in o o e n ( u n d i k e d ) area D i v i s i o n I, "

, ' \ ' , 5 ' R . a r o u n d ' D i v i s i on 2 - - ~ \ " v e n t

. . v / / / / . y / / / ~ v / ~ . ~ .. 0 , v , . , o o ~, - ~ / / / I0 R f r o m

.//~// , vent

D i ' k e 7 ' , r "

/ ~ ~ / / ~ ' ' Tank ' ~ l i-G Gale'

I 0 ' " I O ' m ~

Below g r a d e l o c a t i o n s u c h as 0 sump or trench,

MATERIAL- Flammable Liquid

SMALL/ LOW MODERATE

IPROCESS EQUIP. SIZE

PRESSURE

FLOWRATE

iLARGE/ HIGH

~ Division

7 ~ : ~ Division 2.

Figure 3-4.19 Storage Tanks, Outdoors at Grade.

L

46

NFPA 497A NFPA497A

Vapor return iine t Liquid transfer Ilno

' ~ I ~ " Division 2, 3' R, around

Z - - v a l v e s

r" r"

MATERIAL: Flammable LiQuid

Dlvision I Dfvislon 2.

Figure 3-4.20 Tank Car/Tank Loading and Unloading via Closed System.

Transfer through Dome Only.

47

N F P A 497A N F P A 497A

Vopor r e t u r n I i n e ~ / ~ 7 ~ D i v i s i o n 2, 3' R, a round

' volves

rn 7 I r ,

• L_'2 v t_iquid trans#er 'line • " " ision 2, 3'R

Figure 3-4.21 Tank Car Loading and Unloading via Closed System. Bottom Product Transfer Only.

MATERIAL: Flammable Liquid

OroOe -/ -~~ ~-/,K~</.xc,

C/.C , , /••//Divlslon 2,

5'R

>__-I,~.

Figure 3-4.21 (a) Tank Truck Loading and Unloading via Closed System.

MATERIAL: Flammable Liquid Vapor Density > 1.0

MATERIAL: Flammable Liquid

SMALL/ LARGE/ LOW MODERATE HIGH

PROCESS EQUIP. SIZE"

PRESSURE #

FLOWRATE

Divis ion I

Div is ion 2

48

NFPA 497A NFPA 497A

• . . ~ . / / / , . , ~ Liquid t ransfer line.

L Below grade location such as a Sump or "trench.

Figure 34.22 Tank Car/Tank Truck Loading and Unloading via Open System. Top or Bottom Product Transfer.

MATERIAL: Flammable Liquid

VaDor return line

Division I, 5' R around valves

~ _ i . Liquid transfer line.

F

Division 2 p

Below grade location such as a sump or trench.

Figure 3-4.23 Tank Car/Tarlk Truck Loading and Unloading via Closed System. Transfer through Dome On.Q.~.

MATERIAL: Flammable Liquefied Gas Flammable Compressed Gas Flammable Cryogenic Liquid

~ Division I Division 2

49

. N F P A 4 9 7 A , N F P A 4 9 7 A

Fill pipe.

Division 5 'R DiviSion I,

3 'R

V e n f

Grade /

k i o ' . v I #

_/ Below g r a d e l o c a t i o n such as o sump o r t r e n c h .

18"

I ~ Division I, Division 2

MATERIAL: Flammable Liquid

Figtire 3-4.24 Drum Filling Stadon, Outdoors or Indoors with AdEquate Ventilation.

50

NFPA 497A NFPA 497A

Grade~

Y / ~ \ L

± 18' / / / /

15'

J

Liquid

Below grade Iocatlon such as El sumD o r _ t r e n c h .

18. I~_

L F" 15' .~-I

L., 15' ~I I_ 15" ~ / JL

O.oOe-- ,..

ZLiquid, / /d Below grade as a sump o r t r e n c h .

location such

MATERIAL: Flommo~)le Liquid

Divislon I ~7~ Division 2

NOTE: This diagram does not apply to open pits or open vessels, such as 'dip tanks or open mixing tanks, that normally contain flammable liquids.

Figure 3-4.25 Emergency Impounding Basin or Oil Water Separator (Top) and Emergency or Drainage Ditch Oil/Water Separator (Bottom)• .

51

NFPA 497A NFPA 497A

F Source

Division I, TR

Division 2, 25'R

O r o d e - ~

Polntwhere connections ore regulorly mode

6 - - Division 2,

25! R .

Liquid hydrogen storage container

[~ Division I ~ Division 2

Figure 3-4.26 Liquid Hydrogen Storage System Located Outdoors or in an Adequately Ventilated Building.

Division 2 , - - tS'R

Grade~ " ~

Division 2, 15' R

, Crod. l I .~/~.~

Outdoor

Source at 15' MAX or to floor

Indoor adequate venti lation

Division I ~ Division 2

• Figure 3-4.27 Gaseous Hydrogen Storage System, Located Outdoors or Indoors in an Adequately .

Ventilated Building.

52

NFPA 497A NFPA 49'7A

Bottom of e n c l o s e d a

Ore u rce a t 15' x. o r lower

MATERIAL: L i g h t e r - t h a n - A i r G a s

Figure 3-4.28 Adequately Ventilated Compressor Shelter.

Div is ion " 2 , ~ . .

i n a a e c l u a t e / / / 2 ~ // ventilation - - / 7 / 7 ~ ~ . ~ - ~ D l v l s i on 2,

/ s " " i / ; ,o

Grade - " ~ / / / / / / / / / ~ / / / / / / / / / ~ / ~ Sour ca a t 15' max. o r lower I , l " ~ / / / / M / / / / / / / / / I I ~ m°x'

S o u r c e --/

MATERIAL: Lighter-than-Air Gas

Div is ion I ~ ; ~ D iv is ion 2

Figure3-4.29 Inadequately Ventilated Compressor Shelter.

53

NFPA 497A NFPA 497A

• ~ - - 15'R f rom re l i e f valve 5'R f rom re l ie f v a l v e - ~ ~ J

' ~ / / ~ / ~ _ _ ~ / ~ / ' / - - - 15' R all around

--~-H/~/////~ C°nt °iner~/////F'l ~-Orade

~--Below groae location such as o sump or t r ench .

Dike Height Less than Distance f rom Container to Dike (H Less than X)

5'R f rom re l ie f valve - - ~ . >

/

X

~ / ~ - - - 15' R from re l i e f 15' R all around / ¥ ,

valve

Dike Height Grea te r than Distance f rom C o n t a i n e r - t o Dike (H Grea te r than X)

5'R =ram relief valve

15'R f rom re l i e f valve

f /#-- 15'R a l laround

~ / , ~-Grode

Container

Division I ~ Division 2 MATERIAL: Liquef ied Natural Gas or Other

Cryogenic Flammable Liquids Figure 3-4.30 Storage Tanks for Cryogenic Liquids.

5 4

N F P A 4 9 7 A NFPA 497A

Source -- " 15'R

:01e ow grade loca t i on such

as a sump o r t r e n c h .

Figure 3-4.31 Leakage Source from Equipment Handling Liquefied Natural Gas, Source isLocated

Odtddors At or Above Grade.

Division 2, . . 15' R

•

S o u r c e .

G r a d e ~1

Division 2 15' R, from .opening

Indoors with adequate ventilation

I ~ Division I Division 2

MATERIAL: L i q u e f i e d N a t u r o l G a s o r O t h e r C r y o g e n i c F lammab le G~

Figure 3-4.32 I~eakage Source from Equipment Handling Liquefied Natural Gas in an Adequately

Ventilated Building.

55

N F P A 497A NFPA 497A

• / - , s ' r

D i v i s i o n 2 "

5'.R ~ " i r Grade

Indoors with adequa'te vent i la t ion

~ 5 ' R

Outdoors a t Or above grade

Figure 3-4.33 Leakage Source from Routinely Operating Bleeds, Equipment Handling Liquefied Natural Gas in an

Adequ~/telyVen tilated Building.

MATERIAL: Liquefied Natural Gas or Other Cryogenic Flammable C~s

OivisTon I ~ ~ivision 2

56

N F P A 4 9 7 A N F P A 4 9 7 A

I = p , e SO'

Open clralni

) ra t i ng /elope :1 s torec l sltTon o f " cling arms hoses .

L Water level

Division I ~ Division 2

regulations.

Notes: 1. The "source of vapor" shall be the operating evelope and stored position of the outboard flange cor~nection of the loading arm (or hose).

2. The" berth area adjacent to tanker and barge cargo tanks is to be Division 2 to the follow!ng extenti

,(a) 25 ft (7.6 m) horizontally in all directions on the pier side from that portion of the hull containing cargo tanks.

(b) From the water level to 25 ft. (7.6 m) above the ~argo tanks at their highest position.

Additional locations may have to be classified as required by the presence of other sources of flammable liquids or by Coast Guard or other

Figure 3-4.34 Marine Terminal Handling Flammable Liquids

MATERIAL: Flammable Liquids

57