ASTM D6371-24

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6371 − 17a D6371 − 24
Standard Test Method for
Cold Filter Plugging Point of Diesel and Heating Fuels
This standard is issued under the fixed designation D6371; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers the determination of the cold filter plugging point (CFPP) temperature of diesel and domestic heating
fuels using either manual or automated apparatus.
NOTE 1—This test method is technically equivalent to test methods IP 309 and EN 116.
1.2 The manual apparatus and automated apparatus are both suitable for referee purposes.
1.3 This test method is applicable to distillate fuels, including those containing a flow-improving or other additive, intended for
use in diesel engines and domestic heating installations.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 WARNING—Mercury has been designated by many regulatory agencies as a hazardous materialsubstance that can cause
central nervous system, kidney, and liver damage. serious medical issues. Mercury, or its vapor, may has been demonstrated to be
hazardous to health and corrosive to materials. Caution should be taken Use caution when handling mercury and mercury-
containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s website—http://
www.epa.gov/mercury/faq.htm—for additional information. Users should be aware (SDS) for additional information. The potential
exists that selling mercury and/or mercury containing products in your state or country may be prohibited by law.or
mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For specific warning statements, see Section 7.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D2500 Test Method for Cloud Point of Petroleum Products and Liquid Fuels
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.07 on Flow Properties.
Current edition approved Dec. 1, 2017March 1, 2024. Published December 2017April 2024. Originally approved in 1999. Last previous edition approved in 2017 as
D6371 – 17.D6371 – 17a. DOI: 10.1520/D6371-17A.10.1520/D6371-24.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6371 − 24
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D5771 Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Optical Detection Stepped Cooling Method)
D5772 Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Linear Cooling Rate Method)
D5773 Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Constant Cooling Rate Method)
D7962 Practice for Determination of Minimum Immersion Depth and Assessment of Temperature Sensor Measurement Drift
E1 Specification for ASTM Liquid-in-Glass Thermometers
E644 Test Methods for Testing Industrial Resistance Thermometers
E2251 Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids
E2877 Guide for Digital Contact Thermometers
2.2 IP Standards:
IP 309 Diesel and domestic heating fuels—Determination of cold filter plugging point
Specifications for IP Standard Thermometers
2.3 ISO Standards:
IP 3310ISO 3310 Test sieves—Technical requirements and testing—Part 1: Metal cloth
2.4 European Standards:
EN 116 Diesel and domestic heating fuels—Determination of cold filter plugging point
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
3.1.2 digital contact thermometer (DCT), n—an electronic device consisting of a digital display and associated temperature
sensing probe.
3.1.2.1 Discussion—
This device consists of a temperature sensor connected to a measuring instrument; this instrument measures the temperature-
dependent quantity of the sensor, computes the temperature from the measured quantity, and provides a digital output. This digital
output goes to a digital display and/or recording device that may be internal or external to the device. These devices are sometimes
referred to as a “digital thermometer.”
3.1.2.2 Discussion—
PET is an acronym for portable electronic thermometers, a subset of digital contact thermometers (DCT).
3.2 Definitions of Terms Specific to This Standard:
3.2.1 certified reference material, n—a stable petroleum product with a method-specific nominal CFPP value established by a
6 4
method-specific interlaboratory study following RR:D02-1007 guidelines or ISO Guides 34 and 35.
3.2.2 cold filter plugging point, n—highest temperature, expressed in multiples of 1 °C, at which a given volume of fuel fails to
pass through a standardized filtration device in a specified time when cooled under the conditions prescribed in this test method.
4. Summary of Test Method
4.1 A specimen of the sample is cooled under specified conditions and, at intervals of 1 °C, is drawn into a pipet under a controlled
vacuum through a standardized wire mesh filter. The procedure is repeated, as the specimen continues to cool, for each 1 °C below
the first test temperature. Testing is continued until the amount of wax crystals that have separated out of solution is sufficient to
stop or slow down the flow so that the time taken to fill the pipet exceeds 60 s or the fuel fails to return completely to the test jar
before the fuel has cooled by a further 1 °C.
4.2 The indicated temperature at which the last filtration was commenced is recorded as the CFPP.
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http://www.energyinst.org.uk.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from European Committee for Standardization (CEN), 36 rue de Stassart, B-1050, Brussels, Belgium, http://www.cenorm.be.
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1007. Contact ASTM Customer
Service at service@astm.org.
D6371 − 24
5. Significance and Use
5.1 The CFPP of a fuel is suitable for estimating the lowest temperature at which a fuel will give trouble-free flow in certain fuel
systems.
5.2 In the case of diesel fuel used in European light duty trucks, the results are usually close to the temperature of failure in service
except when the fuel system contains, for example, a paper filter installed in a location exposed to the weather or if the filter
plugging temperature is more than 12 °C below the cloud point value in accordance with Test Method D2500, D5771, D5772, or
D5773. Domestic heating installations are usually less critical and often operate satisfactorily at temperatures somewhat lower than
those indicated by the test results.
5.3 The difference in results obtained from the sample as received and after heat treatment at 45 °C for 30 min can be used to
investigate complaints of unsatisfactory performance under low temperature conditions.
6. Apparatus
6.1 Manual Apparatus:
6.1.1 The apparatus, as detailed in 6.1.2 – 6.1.13, shall be arranged as shown in Fig. 1.
6.1.2 Test Jar, cylindrical, of clear glass, flat bottomed, with an internal diameter of 31.5 mm 6 0.5 mm, a wall thickness of
1.25 mm 6 0.25 mm and a height of 120 mm 6 5 mm. The jar shall have a permanent mark at the 45 mL 6 1 mL level.
NOTE 2—Test jars of the required dimensions may be obtained by selection from jars conforming to Test Method D2500, which specifies a wider diameter
tolerance.
6.1.3 Jacket, brass, watertight, cylindrical, flat bottomed, to be used as an air bath. It shall have an inside diameter of 45 mm 6
0.25 mm, outside diameter of 48 mm 6 0.25 mm, and a height of 115 mm 6 3 mm (see Fig. 2).
6.1.4 Insulating Ring, made from oil-resistant plastics or other suitable material, to be placed in the bottom of the jacket (see 6.1.3)
to provide insulation for the bottom of the test jar. It shall fit closely inside the jacket and have a thickness of 6 mm + 0.3 mm -
0.0 mm.
6.1.5 Spacers (two),approximately 5 mm thick, made of oil-resistant plastics or other suitable material, to be placed as shown in
Fig. 1 around the test jar (see 6.1.2) to provide insulation for the test jar from the sides of the jacket. The spacers shall fit closely
to the test jar and closely inside the jacket. The use of incomplete rings, each with a 2 mm circumferential gap, will accommodate
variations in test jar diameter. The spacers and insulating ring may be made as a single part as shown in Fig. 3.
6.1.6 Supporting Ring, of oil resistant plastics or other suitable non-metallic, non-absorbent, oil-resistant material, used to suspend
the jacket (see 6.1.3) in a stable and upright position in the cooling bath and to provide a concentric location for the stopper (see
6.1.7). A design is shown in Fig. 4 for guidance, but this design may be modified to suit the cooling bath.
6.1.7 Stopper, of oil-resistant plastics or other suitable nonmetallic, nonabsorbent, oil-resistant material, to fit the test jar and the
support ring as shown in Fig. 5. It shall have three holes to accommodate the pipet (see 6.1.8) and the thermometer (see 6.1.9)
and to allow venting of the system. If necessary, when using the high-range thermometer (see 6.1.9), the upper part of the stopper
shall have an indentation to permit the thermometer (see 6.1.9) to be read down to a temperature of –30 °C. A pointer shall be fitted
to the upper surface of the stopper to facilitate location of the thermometer in relation to the bottom of the test jar. A spring wire
clip shall be used to retain the thermometer in the correct position.
6.1.8 Pipet with Filter Unit:
6.1.8.1 Pipet, of clear glass with a calibration mark corresponding to a contained volume of 20 mL 6 0.2 mL at a point 149 mm
6 0.5 mm from the bottom of the pipet (see Fig. 6). It shall be connected to the filter unit (see 6.1.8.2).
6.1.8.2 Filter Unit (see Fig. 7),containing the following elements:
(1) Brass Body, with a threaded cavity that houses the wire mesh holder. The cavity shall be fitted with an O-ring of oil-resistant
plastics. The internal diameter of the central tube shall be 4 mm 6 0.1 mm.
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(2) Brass Screw Cap, to connect the upper part of the body of the filter unit (see 6.1.8.2) to the lower part of the pipet (see
6.1.8.1) to ensure a leak-free joint. An example of satisfactory connection is shown in Fig. 7.
(3) Disc, 15 mm 6 0.1 mm diameter, of plain weave stainless steel wire mesh gauze with a nominal aperture size of 45 μm.
The nominal diameter of the wire shall be 32 μm, and the tolerance for the size of an individual aperture shall be as follows:
No aperture size shall exceed the nominal size by more than 22 μm.
The average aperture size shall be within 6 3.1 μm of the nominal size.
Not more than 6 % of the apertures shall be above the nominal size by more than 13 μm.
(4) Filter Holder of Brass, in which the disc of wire mesh gauze (see 6.1.8.2 (3)) is firmly clamped by a retaining ring pressed
into the filter holder. The diameter of the exposed part of the gauze shall be 12 mm + 0.1 mm – 0.0 mm (see Fig. 8).
(5) Brass Cylinder, threaded on the outside, that can be screwed into the cavity of the body (see 6.1.8.2 (1)) to clamp the filter
holder (see 6.1.8.2 (4)) against the O-ring (6.1.8.2 (1)), The lower end shall have four slots to allow the specimen to flow into the
filter unit.
NOTE 3—The requirements for the wire mesh are taken from IP 3310ISO 3310, to which reference may be made for methods for testing the gauze.
6.1.9 Temperature Measuring Device—Either a liquid-in-glass thermometer as described in 6.1.9.1 or a digital contact
thermometer (DCT) meeting the requirements described in 6.1.9.2.
6.1.9.1 Liquid-in-glass Thermometers, having ranges shown below and conforming to the requirements prescribed in Specifica-
tions E1 or E2251, or Specifications for IP Standard Thermometers.
Thermometer Number
Thermometer Temperature Range ASTM IP
High-range for CFPP down to −38 °C to +50 °C 5C, S5C 1C
−30 °C
Low-range from CFPP below –80 °C to +20 °C 6C 2C
−30 °C
Cooling bath −80 °C to +20 °C 6C 2C
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6.1.9.2 Digital contact thermometer requirements:
Parameter Requirement
DCT Guide E2877 Class F or better
A
Nominal Temperature Range
–38 °C to +50 °C for CFPP down to –30 °C
–80 °C to +20 °C for CFPP below –30 °C
–80 °C to +20 °C for cooling bath
Display Resolution 0.1 °C, minimum
B
Accuracy ±500 mK (±0.5 °C) for combined probe and sensor
Sensor Type Platinum Resistance Thermometer (PRT)
C
Sensor Sheath 4.2 mm OD maximum
D
Sensor Length Less than 10 mm
E
Immersion Depth Less than 40 mm per Practice D7962.
E
Measurement Drift Less than 500 mK (0.5 °C) per year.
E F
Response Time Less than or equal to 4 s per Footnote F
Calibration Error Less than 500 mK (0.5 °C) over the range of intended use.
Calibration Range Consistent with temperature range of use
Calibration Data Four data points evenly distributed over the calibration range that is consistent with the range of
use. The calibration data is to be included in calibration report.
Calibration Report From a calibration laboratory with demonstrated competency in temperature calibration which is
traceable to a national calibration laboratory or metrology standards body.
A
The nominal temperature range may be different than the values shown provided the calibration and accuracy criteria are met.
B
Accuracy is the combined accuracy of the DCT unit which is the display and sensor.
C
Sensor sheath is the tube that holds the sensing element. The value is the outside diameter of the sheath segment containing the sensor element.
D
The physical length of the temperature sensing element.
E
As determined by Practice D7962 or an equivalent procedure.
F
Response Time—The time for a DCT to respond to a step change in temperature. The response time is 63.2 % of the step change time as determined per Section 9 of
Test Method E644. The step change evaluation begins at 20 °C ± 5 °C air to 77 °C ± 5 °C with water circulating at 0.9 m ⁄s ± 0.09 m ⁄s past the sensor.
NOTE 4—A DCT display mounted on the end to the probe’s sheath is likely not suitable due to temperature exposure of the electronics. Consult
manufacturer for temperature limitations.
NOTE 5—When making measurements below –40 °C with a PRT, it may be necessary to use a 1000 ohm sensor in order to obtain accurate measurements.
6.1.9.3 The DCT calibration drift shall be checked at least annually by either measuring the ice point or against a reference
thermometer in a constant temperature bath at the prescribed immersion depth to ensure compliance with 6.1.9.2. See Practice
D7962.
NOTE 6—When a DCT’s calibration drifts in one direction over several calibration checks, it may be an indication of deterioration of the DCT.
6.1.10 Cooling Bath:
6.1.10.1 The type of cooling bath is optional, but it shall be of a shape and size suitable for containing the jacket (see 6.1.3) in
a stable and upright position at the required depth.
6.1.10.2 The bath shall be fitted with a cover with one or more holes in it to accommodate the supporting ring (see 6.1.6). The
jacket (see 6.1.3) may be permanently mounted in the cover.
6.1.10.3 The bath temperature shall be maintained at the required value and tolerance by a refrigeration unit or by the use of
suitable freezing mixtures, ensuring a homogenous temperature in the bath by stirring or other means of agitation. Table 1 lists the
D6371 − 24
bath temperature set-points required in the CFPP procedure. If only one bath is utilized, it must have the ability to change down
to the next lower set-point temperature in a time period not exceeding 2 min 30 s.
6.1.11 Stopcock, glass, with double oblique bore of 3 mm diameter.
6.1.12 Vacuum Source, vacuum pump or water pump powerful enough to ensure an air flow rate in the vacuum regulator of 15 L ⁄h
6 1 L/h for the duration of the test.
6.1.13 Vacuum Regulator, consisting of a glass bottle, at least 350 mm high, not less than 5 L capacity, partially filled with water.
It shall be closed by a stopper with three holes of convenient diameters for glass tubes. Two tubes shall be short and shall not go
below the water level. The third tube, with an internal diameter of 10 mm 6 1 mm, shall be long enough for one end to be
approximately 200 mm beneath the surface of the water while the other end reaches a few centimetres above the stopper. The depth
of the immersed part shall then be adjusted to obtain a depression of 200 mm 6 1 mm of water (2 kPa 6 0.05 kPa) on the
manometer, which shall contain water. A second empty 5 L bottle shall be fitted in the line to serve as a vacuum reservoir to ensure
a constant depression. The arrangement is shown in Fig. 1.
6.1.14 Stopwatch, with a graduation or reading of 0.2 s or lower, with an accuracy of 0.1 % over a period of 10 min.
6.2 Automated App
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