Designation: D 4539 – 98 An American National Standard

Standard Test Method forFilterability of Diesel Fuels by Low-Temperature Flow Test(LTFT)1

This standard is issued under the fixed designation D 4539; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.

1. Scope

1.1 This test method estimates the filterability of diesel fuelsin some automotive equipment at low temperatures.1.2 The values stated in SI units are to be regarded as the

standard. The values in parentheses are for information only.1.3 This standard does not purport to address all of the

safety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.For specificprecautionary statements, see 7.1, 7.2.1, 7.3, 7.5, 7.9.3, 7.11,and A1.1.7.

2. Referenced Documents

2.1 ASTM Standards:D 97 Test Method for Pour Point of Petroleum Oils2

D 975 Specification for Diesel Fuel Oils2

D 1655 Specification for Aviation Turbine Fuels2

D 2500 Test Method for Cloud Point of Petroleum Oils2

D 3117 Test Method for Wax Appearance Point of DistillateFuels3

D 3699 Specification for Kerosine3

E 1 Specification for ASTM Thermometers4

2.2 Coordinating Research Council, Inc.CRC Report No. 528 Diesel Fuel Low-Temperature Oper-ability Field Test5

2.3 Canadian General Standards Board:CAN/CGSB-3.0, No. 14.01-M86, Low Temperature FlowTest (LTFT) for Diesel Fuels

NOTE 1—CAN/CGSB-3.0, No. 140.1-M86 is essentially equivalent toTest Method D 4539 but the differences in apparatus and procedures mayor may not yield different results.

3. Summary of Test Method

3.1 The temperature of a series of test specimens of fuel is

lowered at a prescribed cooling rate. Commencing at a desiredtest temperature and at each 1°C interval thereafter, a separatespecimen from the series is filtered through a 17-µm screenuntil a minimum LTFT pass temperature is obtained. Theminimum LTFT pass temperature is the lowest temperature,expressed as a multiple of 1°C, at which a test specimen can befiltered in 60 s or less.3.2 Alternatively, a single specimen may be cooled as

described under 3.1 and tested at a specified temperature todetermine whether it passes or fails at that temperature.

4. Significance and Use

4.1 The Low Temperature Flow Test results are indicative ofthe low temperature flow performance of the test fuel in somediesel vehicles (per CRC Report No. 528). The test method isespecially useful for the evaluation of fuels containing flowimprover additives.4.2 The test method can be used to supplement other

measurements of diesel fuel low temperature behavior (inaccordance with Test Methods D 97, D 2500, and D 3117).

5. Apparatus

5.1 Glass Specimen Vessels,6 several 300-mL, clear, heatresistant, wide-mouthed glass bottles having markings indicat-ing 200 mL6 10 mL and 50–60 mm ID or clear, heat resistant,tall form beakers with no pour spouts and equivalent dimen-sions.5.2 Glass Receiver Vessels, clear, heat resistant, glass con-

tainers graduated through 180 mL in 10 mL6 2 mL incre-ments.5.3 Filtering Assembly(see Fig. 1), including a storage lid

or some other form of cover, glass tubing, flexible fuel resistanttubing, pinch clamp and rubber stopper, or other means toprovide a vacuum seal.5.4 Filter, as shown in detail in Fig. 2, for each sample

container (300-mL beaker). 304SS sintered screen7 is a twillDutch weave mesh with a nominal filtration rating of 17 µm.The mesh is 65 wires/cm (165 wires/in.) X 303/315 wires/cm(770/800 wires/in.). The wire strands have diameters of 0.0071cm (0.0028 in.) and 0.0046 cm (0.0018 in.), respectively. The

1 This test method is under the jurisdiction of Committee D-2 on PetroleumProducts and Lubricants and is the direct responsibility of Subcommittee D02.07 onFlow Properties.

Current edition approved June 10, 1998. Published August 1998. Originallypublished as D 4539 – 85. Last previous edition D 4539 – 94.

2 Annual Book of ASTM Standards, Vol 05.01.3 Annual Book of ASTM Standards, Vol 05.02.4 Annual Book of ASTM Standards, Vol 14.03.5 Available from Coordinating Research Council, Inc., 219 Perimeter Center

Parkway, Atlanta, GA 30346.

6 Borosilicate heat resistant glass or equivalent beakers are suitable for thispurpose.

7 Suitable filter cloth is available from Pall Aerospace Co., Pall Aeropower Corp.,6301 49th St. N, Pinellas Park, FL 33781.

1

AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr., West Conshohocken, PA 19428

Reprinted from the Annual Book of ASTM Standards. Copyright ASTM

nominal filtration rating indicates a 98 % removal by massweight of all particles equal to or greater than 17 µm.5.5 Programmable Cooling System, capable of cooling mul-

tiple specimens to the desired temperature at a mean rate of1.0°C per hour between + 10°C and − 30°C. Absolute devia-tion of any single temperature point along the prescribed ramp

FIG. 1 LTFT Sample Filtration Assembly

FIG. 2 LTFT Filter Assembly

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function must not exceed 0.5°C in any specimen. The system’ssize and shape are optional. Either liquid or air baths areacceptable.5.6 Stop Watch or Electric Timer, capable of measuring

tenths of a second.5.7 Vacuum System, capable of maintaining a constant

vacuum of 20.0 kPa6 0.2 kPa (1506 1.5 mm Hg)(Warning—Mercury is a poison. SeeA2.4) below atmosphericpressure at the receiver for the duration of each determination.5.8 Thermometers, total immersion type, having a range

from − 80 to + 20°C, and conforming to the requirements forThermometer 114C for air baths or Thermometer 5C for liquidbaths as prescribed in Specification E 1.

6. Reagents

6.1 Jet A Aviation Turbine Fuel—As specified in Specifica-tion D 1655, kerosene, as specified in Specification D 3699,Grade No. 1 (or Grade Low Sulfur No. 1), as specified inSpecification D 975, or equivalent liquid that will not separateat temperatures down to –30°C.

7. Procedure

7.1 Filter a fresh specimen of test fuel (Warning—Combustible liquid. See A2.3) at 15°C or higher, through dry,lintless filter paper, having a nominal filtration rating of lessthan 17 µm.7.2 Clean and inspect the filter assembly before each test.

Filters shall be standardized before initial use and after every20 tests as specified in Annex A1.7.2.1 Clean the assembled filter with two solvents using a

vacuum to draw the solvents through the screen. Begin withthree successive washes of at least 50 mL of heptane(Warning—Flammable. See A2.2), followed by three succes-sive washes of at least 50 mL of acetone (Warning—Extremely flammable. See A2.1). Air dry the filters afterwashing.7.2.2 Visually inspect each filter assembly for screen dam-

age or the presence of particulates. Discard any damaged filterscreens. Reclean and standardize any filter screens containingparticulates.7.3 Pour 200 mL of clean, dry fuel (Warning—

Combustible liquid. See A2.3) into each of the several 300-mLbeakers.7.4 Insert a clean standardized filter assembly into each

specimen container and tightly cover the joint (Point A of Fig.1) and lid with aluminum foil to exclude condensation.7.5 Insert a total immersion thermometer into one or more

separate, identical glass specimen bottles or beaker(s) contain-ing 200 mL of Jet A aviation turbine fuel kerosine, or GradeNo. 1 (or Grade Low Sulfur No. 1) (Warning—Combustibleliquid. See A2.3) or equivalent liquid that will not phaseseparate at temperatures down to − 30°C. The thermometerbulb should be positioned in the center of the bottle or beakerapproximately half way between the top and the bottom of theliquid.7.6 Place the specimen bottles or beaker (from 7.3 through

7.5) into the cooling bath at a temperature that is at least 5°Cabove the wax appearance point (Test Method D 3117) orcloud point (Test Method D 2500) of the fuel under test.

During multiple specimen testing, a sufficient number oftemperature monitoring vessels (from 7.5) must be distributedthroughout the cooling bath to insure all test specimen tem-peratures conform with precision requirements. The position-ing of all bottles or beakers shall permit unimpeded circulationof the cooling medium across their bottoms and sides.7.7 Close the cooling bath’s door, if it has one.7.8 Start the temperature programmer at a rate of − 1.0°C/h.7.9 Before the sample reaches the desired test temperature,

check the following:7.9.1 Apply the pinch clamp at Point B (Fig. 1).7.9.2 Place an empty receiver vessel in position.7.9.3 Adjust the vacuum to 20.0 kPa6 0.2 kPa (150 + 1.5

mmHg) (Warning—Mercury is a poison. See A2.4) belowatmospheric pressure.7.9.4 Reset the timer.7.10 When the specimen has cooled to the desired testing

temperature, use the filter assembly stem to gently stir (15revolutions at approximately 1 turn/s) the specimen to disperseany settled wax crystals. Remove the aluminum foil andconnect the filtration apparatus joint at Point A (Fig. 1). If thespecimen has to be removed from the cooling bath forfiltration, these steps shall be completed within 1 min.7.11 Filter the specimen by removing the pinch clamp at

Point B (Fig. 1) while simultaneously starting the timer. Ifnecessary, adjust the vacuum system to maintain a vacuum of20.0 kPa + 0.2 kPa (150 + 1.5 mmHg). (Warning—Mercury isa poison. See A2.4) below atmospheric pressure.7.12 Reapply the pinch clamp at Point B (Fig. 1) at precisely

60 s or when suction is lost, whichever occurs first. Record thevolume of specimen filtered in millilitres and the testingtemperature in degrees Celsius.7.13 Pass—Fail Criteria:7.13.1 Passing Result—The result is considered a pass if

most of the specimen has been siphoned into the receivervessel within 60 s, and suction is lost due to the low level ofspecimen remaining in the specimen vessel.

NOTE 2—Typically, a volume of approximately 180 mL will becollected in the receiver vessel in a passing result, but this volume mayvary due to differences in specimen vessel dimensions and thetemperature/volume characteristics of the fuel.

7.13.2 Failing Result—The result is considered a fail ifsuction is not lost within 60 s.7.14 To determine the minimum LTFT pass temperature,

repeat 7.9 through 7.12 on subsequent test specimens that havebeen cooled 1°C lower than the previous test temperature, untilat least one passing result and one failing result are obtained(see 7.13.1 and 7.13.2).7.15 Alternatively, cool a single specimen to a desired

temperature and determine whether a passing (7.13.1) or afailing (7.13.2) result is obtained.

8. Report

8.1 Report the temperature of the last passing result re-corded in 7.14 as:Minimum LTFT Pass Temperature5_______°C.8.2 Alternatively, report the result recorded in Step 7.15 as:

Pass or Failat ________°C.

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9. Precision and Bias

9.1 Precision—The precision data were obtained in a coop-erative program in which fuels were investigated over thetemperature range from − 10 to − 25°C. The precision of thistest method as determined by the statistical examination ofinterlaboratory test results is as follows:9.1.1 Repeatability—The difference between successive re-

sults obtained by the same operator with the same apparatusunder constant operating conditions on identical test materialwould, in the long run, in the normal and correct operation ofthe test method exceed the following value only in one case intwenty.

Repeatability5 2°C (1)

9.1.2 Reproducibility—The difference between two singleand independent results obtained by different operators work-ing in different laboratories on identical test material would, inthe long run, in the normal and correct operation of the testmethod, exceed the following value only in one case in twenty.

Reproducibility5 4°C (2)

9.2 Bias—There being no criteria for measuring bias inthese test product combinations, no statement of bias can bemade.

10. Keywords

10.1 diesel fuel; filterability; flow; low temperature; LTFT

ANNEXES

(Mandatory Information)

A1. LTFT WIRE FILTER SCREEN STANDARDIZATION PROCEDURE

A1.1 Procedure

A1.1.1 Dismantle and inspect the wire filter screen assem-bly. Discard any damaged screens.A1.1.2 Reassemble and wash the filter assembly as speci-

fied in 7.2.A1.1.3 Filter the Vistone8 A-30 reference oil through dry,

lintless filter paper, having a normal filtration rating of less than17 µm at room temperature.A1.1.4 Pour 150 mL of clean, dry Vistone8 A-30 into a

300-mL heat resistant tall-form beaker7 with no pour spout.A1.1.5 Insert the filter assembly into the sample.A1.1.6 Insert a thermometer into the beaker and wait until

the temperature reading stabilizes.A1.1.7 Filter the Vistone8 A-30 by applying a vacuum of

20.0 kPa6 0.2 kPa (1506 1.5 mmHg) (Warning—Mercuryis a poison. See A2.4) below atmospheric pressure whilesimultaneously starting the stopwatch.A1.1.8 Stop the timer at the instant the filter assembly loses

suction on the oil and begins drawing in air.A1.1.9 Record the filtration time in seconds and the filtra-

tion temperature to the nearest 0.5°C.A1.1.10 Calculate the temperature correction factor corre-

sponding to the filtration temperature using the followingequations. The viscosity of the Vistone8A-30 reference oil willbe provided by the vendor.

log log ~vt 1 0.7! 5 A2 B log T (A1.1)

Ct 5 v20/vt (A1.2)

where:vt 5 viscosity of reference fluid at specified temperature,

mm2

v20 5 viscosity of reference fluid at 20°C, mm2,A, B 5 constants to be solved,

Ct 5 temperature correction factor at specified tempera-ture,

T 5 temperature in Kelvin at whichvt is determined,T 5 273.1 + °C.Example: Determine temperature correction factor at 10°C.

If the viscosities for Vistone8 A-30are:27.04 mm2/s (cSt) at 40°C5.38 mm2/s (cSt) at 100°C

A1.1.11 Enter the viscosity and corresponding temperaturedata in (Eq A1.1)

log log ~vt 1 0.7! 5 A2 B log T (A1.3)

log log ~27.041 0.7! 5 A2 B log ~273.11 40! (A1.4)

log log ~5.381 0.7! 5 A2 B log ~273.11 100! (A1.5)

A1.1.12 Solve forA andB

A5 8.8500,B5 3.4823 (A1.6)

A1.1.13 Determine the viscosity of Vistone8 A-30 at 20°Cand 10°C using (Eq A1.1)

log log ~v20 1 0.7! 5 8.85002 3.4823 log~273.11 20!(A1.7)

v20 5 64.75 (A1.8)

log log ~v10 1 0.7! 5 8.85002 3.4823 log~273.11 10!(A1.9)

v10 5 111.33 (A1.10)

A1.1.14 Calculate the temperature correction factor at 10°Cusing (Eq A1.2)

Ct 5 v20/vt (A1.11)

C10 5 64.75/111.335 0.582 (A1.12)

A1.1.15 Multiply the actual filtration time in seconds by thecorrection factor to obtain the corrected filtration time. (Ex-ample: for an actual filtration time of 79 s at 10°C, thecorrected filtration time would be 793 0.5825 46 s (A1.11),and the screen would be reported as acceptable.)

A1.2 Report8 Registered trademark of Exxon Chemical Co.

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A1.2.1 If the corrected filtration time falls between 45 and53 s, inclusive, the screen is reported as acceptable for use in

the LTFT. If the corrected filtration time falls outside thisrange, the screen is unacceptable and should be discarded.

A2. PRECAUTIONARY STATEMENTS

A2.1 Acetone

Warning—Extremely flammable.Vapors may cause flash fire.Keep away from heat, sparks, and open flame.Keep container closed.Use with adequate ventilation.Avoid build-up of vapors, and eliminate all sources of

ignition, especially nonexplosion proof electrical apparatus andheaters.Avoid prolonged breathing of vapor or spray mist.Avoid contact with eyes or skin.

A2.2 n-Heptane

Warning—Flammable. Harmful if inhaled.Keep away from heat, sparks, and open flame.Keep container closed.Use with adequate ventilation.Avoid prolonged breathing of vapor or spray mist.Avoid prolonged or repeated skin contact.

A2.3 Combustible Liquid

Warning—Combustible. Vapor harmful.

Keep away from heat, sparks, and open flame.Keep container closed.Use with adequate ventilation.Avoid prolonged breathing of vapor or spray mist.Avoid prolonged or repeated skin contact.

A2.4 Mercury

Warning—Poison. May be harmful or fatal if inhaled orswallowed.Vapor harmful, emits toxic fumes when heated.Vapor pressure at normal room temperature exceeds thresh-

hold limit value for occupational exposure.Do not breathe vapor.Keep container closed.Use with adequate ventilation.Do not take internally.Cover exposed surfaces with water, if possible, to minimize

evaporation.Do not heat.Keep recovered mercury in tightly sealed container prior to

sale or purification. Do not throw in sink or in rubbish.

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This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsibletechnical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make yourviews known to the ASTM Committee on Standards, 100 Barr Harbor Drive, West Conshohocken, PA 19428.

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