ASTM D5306-24

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Designation: D5306 − 92 (Reapproved 2018) D5306 − 24
Standard Test Method for
Linear Flame Propagation Rate of Lubricating Oils and
Hydraulic Fluids
This standard is issued under the fixed designation D5306; 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 Scope*
1.1 This test method covers the determination of the linear flame propagation rates of lubricating oils and hydraulic fluids
supported on the surfaces of and impregnated into ceramic fiber media. Data thus generated are to be used for the comparison of
relative flammability.
1.2 This test method should be used to measure and describe the properties of materials, products, or assemblies in response to
heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire risk
of materials, products, or assemblies under actual fire conditions. However, results of this test method may be used as elements
of fire risk which takes into account all of the factors that are pertinent to an assessment of the fire hazard of a particular end use.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
1.5 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:
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 Military Specifications:
MIL-H-83282C Hydraulic Fluid, Fire Resistant, Synthetic Hydrocarbon Base, Aircraft NATO Code Number H-537
MIL-H-46170B Amm.1, Hydraulic Fluid, Rust Inhibited, Fire Resistant, Synthetic Hydrocarbon Base
3. Terminology
3.1 Definitions:
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.N0 on Hydraulic Fluids.
Current edition approved Oct. 1, 2018March 1, 2024. Published November 2018March 2024. Originally approved in 1992. Last previous edition approved in 20132018
as D5306 – 92 (2013).(2018). DOI: 10.1520/D5306-92R18.10.1520/D5306-24.
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*A Summary of Changes section appears at the end of this standard
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D5306 − 24
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 linear flame propagation rate, n—the average quotient of the distance of flame travel and the time required for the flame
front to travel that distance.
4. Summary of Test Method
4.1 A section of a ceramic fiber support medium (string) is impregnated with the sample under specific conditions. The
impregnated fiber is placed on a standard support. The sample is ignited and the time required for the flame front to propagate
across a measured distance is determined by use of a thermoelectric system. The average propagation rate is then calculated from
the measured distance of flame travel and the time required for the flame front to propagate over that distance.
5. Significance and Use
5.1 The linear flame propagation rate of a sample is a property that is relevant to the overall assessment of the flammability or
relative ignitability of fire resistance lubricants and hydraulic fluids. It is intended to be used as a bench-scale test for distinguishing
between the relative resistance to ignition of such materials. It is not intended to be used for the evaluation of the relative
flammability of flammable, extremely flammable, or volatile fuels, solvents, or chemicals.
6. Apparatus
6.1 Apparatus for measurement of linear flame propagation rates:
FIG. 1 Apparatus for Determination of Linear Flame Propagation Rates
6.1.1 Open Top Stainless Steel Box, as shown in Fig. 1.
6.1.2 Recorder, stripchart, fast responses. A zero-centered recorder with a 65 mV range and a one-half second full-scale deflection
capacity has been found to be satisfactory. A chart speed of at least 1 in. ⁄min has been used for most studies.
6.1.3 Differential Thermocouple Pair, 30 gauge with bare junctions and double fiberglass wrap insulation, ISA, Type J or Type K
may be prepared from any premium grade thermocouple wire.
6.1.4 Fume Hood, draft-free when ventilation system is not operative.
6.1.5 Weights, 50 g 6 0.01 g, with attached hooks; two required.
6.1.6 Chrome-Plated Tube or Rod, 15 mm diameter by 375 mm long.
6.1.7 Porcelain or Glass Dish, approximately 135 mL capacity.
D5306 − 24
7. Materials
7.1 Absorbent Paper Wipers, 375 mm by 213 mm.
7.2 Ceramic Fiber, twisted yarn type 390/312, 4/5, 2.72 or type 390/312, 3/4, 2.72. Ceramic fiber size used shall be agreed upon
by supplier and consumer and shall be specified in test report.
7.3 Ignition Source, any paper book matches or wooden kitchen matches can be used.
8. Procedure
8.1 Tie small loops in each end of a 500 mm section of ceramic fiber support (string). Place a few millilitres of the sample to be
studied in an evaporating dish. Immerse the ceramic fiber support (string) in the liquid sample for 60 s. Avoid immersion of the
loops at the end of the string.
8.2 While the ceramic fiber support (string) is immersed in the sample, carefully wrap an absorbent paper wiper around the 15 mm
diameter chrome plated rod. Leave one end of the rod uncovered by the wiper.
8.3 Remove the ceramic fiber support (string) section from the liquid sample and attach a 50 g weight to the loop at each end. Fix
the chrome-plated rod with its absorbent paper wrapping in a horizontal position and hang the soaked string section with attached
weights over the unwrapped section of the rod. Press down gently on the uppermost weight to cause the soaked string to pass over
the bare rod, flexing gently as it moves. When the lower weight has been drawn up to the rod, reverse the process until the first
weight has again been drawn up the rod. Repeat the cycle four times to work the sample thoroughly into the string.
8.4 Transfer the string with attached weights to the covered portion of the chrome-plated rod. Pass the string over the absorbent
paper in the manner described in 8.3. After each complete double cycle, lift the string from the paper, rotate it through 180° as
it is held taut in a vertical position and then replace it on a fresh area of the absorbent medium. Again pass the string over the paper
in the manner described in 8.3. Repeat until four double cycles have been completed.
8.5 Place the string support and thermocouple holder in a draft-free hood with the ventilation turned off. Level the apparatus with
a spirit level. Place the prepared string on the string supports. The attached weights should be left in place to provide tension in
the string. Adjust the differential thermocouple junctions so that they are exactly 2 mm directly above the string. Connect the
differential thermocouple pair to the fast-response, zero-centered strip chart recorder.
8.6 Start the recorder chart after an appropriate warm-up period. With an ignition source, ignite the sample on the string near its
support at one end of the apparatus. Permit the flame to advance along the string past each thermocouple until it extinguishes itself
upon reaching the opposite string support. Stop the recorder and start the hood ventilator to exhaust the combustion products of
the sample. (Warning—Take extreme care to avoid inhalation of the combustion products as extremely toxic substances are
formed during the combustion of some synthetic materials, especially halogenated and phosphorus-based compounds.)
8.7 Measure the horizontal distance between the thermocouples and interval between the
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