GB/T 382-2025 Kerosene and Jet Fuel Smoke Point Determination Method

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Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: GB/T 382—2025
• Chinese name: Kerosene and Jet Fuel Smoke Point Determination Method
• English name: Test method for smoke point of kerosene and aviation turbine fuel
• Replacement relationship: replaces GB/T 382—2017
• First publication: 1965 year; first revision in 1978 year; second revision in 1983 year; third revision in 2017 year; this is the fourth revision
• Proposed and administered by: National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280)
• Publication/implementation: published on 2025-10-05, implemented on 2026-05-01

2. Scope of application and non-applicability

• This document describes manual and automatic methods for determining the smoke point of kerosene and jet fuel.
• Applicable to the determination of the smoke point of kerosene and jet fuel.
• The precision data for manual instruments apply to the atmospheric pressure range 70 kPa to 102 kPa; the precision data for automatic instruments apply to the atmospheric pressure range 75 kPa to 102 kPa; for smoke point determination under other pressures, the precision is for reference use.
• Non-applicable scope: not provided in the available source.

3. Method principle

The test sample is burned in a closed wick lamp, which is calibrated with a pure hydrocarbon mixture of known smoke point. The maximum smokeless flame height of the test sample is determined by manual instrument or automatic instrument, and the reported value is accurate to 0.1 mm.

4. Reagents and materials (purity / preparation)

Unless otherwise specified, the reagents used in the test process are all of analytical grade or above purity.

Table 1 Standard fuel mixture

5. Instruments and equipment

• 5.1 Smoke point lamp (manual), see Figure 1, meets the requirements of Appendix A.
• 5.2 Smoke point lamp (automatic), schematic diagram see Figure 2, meets the requirements of Appendix A. Also called automatic smoke point meter, equipped with a digital camera connected to a computer for analyzing and recording flame height; a candle holder displacement system for adjusting flame height; an atmospheric pressure acquisition system associated with a calibration database for selecting the correct correction value to automatically calculate the correction coefficient defined in 9.1.3. The minimum resolution of the dedicated software of the digital camera for flame height measurement is 0.05 mm.
• 5.3 In case of dispute, the automatic instrument determination method shall be the arbitration method.
• 5.4 Barometer: accuracy 0.5 kPa.
• 5.5 Wick: ordinary grade cotton yarn woven into a dense round strip, with the following properties:
  • a) Face diameter yarn: 17 strands, 3 plies 66 count yarn;
  • b) Inner diameter yarn: 9 strands, 4 plies 100 count yarn;
  • c) Weft yarn: 2 plies 40 count yarn;
  • d) Weft density: 6 threads/cm.
• 5.6 Pipette: A grade, conforming to GB/T 12807—2021 or GB/T 12808—2015 specifications.
• 5.7 Graduated cylinder: 25 mL, graduation value 1 mL.
• 5.8 Thermometer: temperature measurement range 0 ℃ to 50 ℃, graduation value 1 ℃.
• 5.9 Qualitative filter paper.
• 5.10 Extractor: Soxhlet extractor or similar extraction device.
• 5.11 Oven: controlled temperature 105 ℃±5 ℃.
• 5.12 Desiccator: contains a certain amount of desiccant, with a volume sufficient to store a certain amount of wicks.

6. Recommended operating conditions

• Sample temperature: 20 ℃±5 ℃ (see Chapter 7, 10.1.2).
• Combustion stabilization time: 5 min (see 10.2.2, 10.3.4).
• Initial flame height: approximately 10 mm (see 10.2.2, 10.3.4).
• Wick drying conditions: dry at 105 ℃±5 ℃ for 30 min (see 8.3.1, Appendix B).
• Number of wick extraction cycles: at least 25 times (see 8.3.1, Appendix B).
• Manual instrument reading accuracy: accurate to 0.5 mm (see 10.2.3).
• Automatic instrument reading accuracy: accurate to 0.1 mm (see 10.3.5).
• Result reporting accuracy: 0.1 mm (see Chapter 4, Chapter 13).
• Atmospheric pressure recording accuracy: 0.1 kPa (see Chapter 13).
• Other operating conditions: not provided in the available source.

7. Sampling and sample preparation

• Sample according to GB/T 4756, GB/T 27867 or SH/T 0635.
• After collecting the sample, allow the sample to reach room temperature (20 ℃±5 ℃) and then test as soon as possible.
• If necessary, auxiliary equipment may be used to accelerate sample temperature equilibration, but local overheating of the sample that causes volume reduction should be avoided.
• If the sample is turbid or contains impurities, filter it with qualitative filter paper.

8. Analysis procedure

8.1 Instrument preparation

• Manual instrument: Install the smoke point lamp (manual) vertically in a completely draft-free room. Carefully inspect each smoke point lamp (manual) to ensure that the air holes of the platform and the air inlet of the candle holder are clean, unobstructed, and of appropriate size. The installed platform should keep the ventilation holes completely unobstructed. Note: Slight nonconformity of these parts will significantly affect the precision of the results. During the test, if the room is not completely unventilated, the smoke point lamp (manual) should be placed vertically in a box made of flame-retardant material (not containing asbestos) with an openable front door, and the top of the box should be at least 150 mm higher than the top of the chimney, and the inner side of the box should be painted dark black.
• Automatic instrument: Prepare the instrument according to the manufacturer's operating manual.
• Wick treatment:
  • 8.3.1 All wicks, whether new or previously used in testing, shall be placed in an extractor and extracted with a mixture of equal volumes of toluene and anhydrous methanol for at least 25 cycles. For help information on wick extraction and number of cycles, see Appendix B. After extraction is completed, place the wicks in a clean container or on absorbent paper, first allowing the wicks to partially dry in a fume hood; or dry the wicks using a forced-ventilation and explosion-proof oven, or a combination of both methods. Dry at 105 ℃±5 ℃ for 30 min, and store in a desiccator before use.
  • 8.3.2 As long as it can be demonstrated that the wicks have been extracted according to the method specified in 8.3.1, commercially available extracted wicks may be used. Store purchased extracted wicks in a desiccator before use. After use, extract these wicks as specified in 8.3.1 before reuse.

8.2 Instrument calibration

• Manual instrument:
  • 9.1.1 Before using the instrument, perform instrument confirmation according to the procedure in 9.1.4, or calibrate according to the procedure in 9.1.2 as needed. When the instrument or operator changes, or when the atmospheric pressure reading changes by more than 0.7 kPa, the instrument should be recalibrated (see 9.1.2).
  • 9.1.2 Calibrate the instrument according to the procedure specified in Chapter 10, using the determination of the two standard fuel mixtures specified in 6.4. If possible, make the smoke point determination value of the test sample fall between the smoke point determination values of the two standard fuel mixtures; if not possible, use the two standard fuel mixtures whose smoke point determination values are closest to the smoke point determination value of the test sample.
  • 9.1.3 The correction coefficient f of the instrument is calculated according to formula (1): f = [(As/Ad) + (Bs/Bd)] / 2 ………………(1) Where: f ——— correction coefficient of the instrument; As ——— standard value of the smoke point of the first standard fuel mixture, in millimeters (mm); Ad ——— measured value of the smoke point of the first standard fuel mixture, in millimeters (mm); Bs ——— standard value of the smoke point of the second standard fuel mixture, in millimeters (mm); Bd ——— measured value of the smoke point of the second standard fuel mixture, in millimeters (mm). If the smoke point determination value of the test sample is exactly the same as the smoke point determination value of one standard fuel mixture, then the other standard fuel mixture should be selected as the standard fuel mixture with a slightly higher smoke point determination value. If not, select another standard fuel mixture whose smoke point determination value is closest to the smoke point determination value of the test fuel.
  • 9.1.4 When the instrument is in use, each operator shall, every day, conduct a test with a quality control sample to verify the instrument status. Record the results and compare them with the average value of the control sample obtained from a control chart or an equivalent statistical analysis technique. If the result exceeds the control limit or when a new instrument is used, the instrument shall be calibrated.
• Automatic instrument:
  • 9.2.1 The instrument shall have a calibration database used to store the values of the standard fuel mixtures in Table 1. The values of each calibration test of the standard fuel mixtures and the atmospheric pressure observed at that time shall all be stored in the database.
  • 9.2.2 The instrument shall have the function of automatically calculating the calibration coefficient f according to formula (1) and calculating the smoke point value of the test sample according to formula (2). That is, the instrument automatically searches in the calibration database storing the values of the standard fuel mixtures listed in Table 1, so that the measured smoke point value of the test sample lies between the measured values of two standard fuel mixtures; if the measured smoke point value of the test sample exceeds the range of the smoke point measured values of the standard fuels, then select two standard fuel mixtures whose smoke point measured values are close to the smoke point measured value of the test sample; if the measured smoke point value of the test sample is exactly the same as the smoke point measured value of one standard fuel mixture, then the other standard fuel mixture shall be selected as the standard fuel mixture with a slightly higher smoke point measured value. Note: A digital camera and corresponding software replace the operator in observing the flame, so the instrument does not need to be recalibrated when the operator changes.
  • 9.2.3 Instrument calibration shall be carried out within the recorded atmospheric pressure ±0.7 kPa. If the instrument has no calibration values for the 7 standard fuel mixtures listed in Table 1 at the observed pressure ±0.7 kPa, then calibrate the instrument according to 9.2.4; if the instrument has already been calibrated at the observed pressure ±0.7 kPa (the instrument stores the calibration values of the 7 standard fuel mixtures listed in Table 1), then check the instrument according to 9.2.5. Note: If the automatic instrument stores the smoke point values of the standard fuel mixtures at different pressures, then when the atmospheric pressure changes by more than 0.7 kPa, the instrument does not need to be recalibrated. Based on the atmospheric pressure value input at the start of the test, the instrument automatically selects and uses the stored smoke point calibration values of the standard fuel mixtures. If the calibration values at that atmospheric pressure have not yet been stored, the instrument will prompt the operator to calibrate.
  • 9.2.4 According to the procedure in Chapter 10, calibrate the instrument with the 7 standard fuel mixtures specified in 6.4.
  • 9.2.5 Periodically (not exceeding 7 d) or when the instrument is changed, conduct a test with a quality control sample to verify the performance of the instrument, so as to determine that the instrument meets the statistical control limits specified in NB/SH/T 0843. If the result exceeds the control limit, the instrument shall be recalibrated.

8.3 Test Procedure

• 10.1 Assembly of the oil reservoir:
  • 10.1.1 Select a dried wick with a length not less than 125 mm and insert it into the wick tube (see Figure 3). Do not cause any curling of the wick in the wick tube. In case of dispute or arbitration testing, a new wick treated according to the method in 8.3 shall be used. After the wick is inserted into the wick tube, the burning end of the wick tube may be pre-wetted with the test sample.
  • 10.1.2 At room temperature, measure about 20 mL (not less than 10 mL) of the prepared test sample (the test sample temperature shall be 20 ℃±5 ℃) and pour it into a clean, dry oil reservoir.
  • 10.1.3 Place the wick tube into the oil reservoir and tighten it. The test sample should not fall into the vent hole of the oil reservoir. If the wick trimming assembly is not used, a clean blade or other sharp tool may be used to trim the uneven wick head flat and make the wick protrude 6 mm from the wick tube.
  • 10.1.4 Some blades or tools have a protective coating, which may first be wiped with qualitative filter paper and then cleaned with n-heptane to remove the coating.
  • 10.1.5 A wick trimming assembly (see Figure 4) may also be used to make a wick with a top end free of distortion and wear. Insert the wick trimming assembly holder at the top of the wick tube (step 1 in Figure 5), and pass the long pointed-jaw pliers through the wick tube (step 2 in Figure 5). Grasp the wick with the pointed-jaw pliers (step 3 in Figure 5), and carefully pass it through the wick tube to avoid distortion (step 4 in Figure 5). Install the wick tube into the oil reservoir and tighten it (step 5 in Figure 5). Use a new, clean, sharp blade to cut off the wick above the holder (step 6 in Figure 5). After removing the holder, the length of the wick should be appropriate (step 7 in Figure 5).
  • 10.1.6 After assembling the wick tube and the oil reservoir, wait until the wick is completely wetted (may be soaked for 5 min) before proceeding to the subsequent steps.
• 10.2 Manual instrument test procedure:
  • 10.2.1 Insert the oil reservoir into the smoke point lamp (manual).
  • 10.2.2 Light the wick and adjust the flame height to about 10 mm, and burn for 5 min (see Figure 6 and Figure 7).
  • 10.2.3 Raise the wick until smoke appears, then slowly lower the flame height; its shape may appear in the following several situations:
    • a) A long pointed, slightly visible smoky, unstable and jumping flame.
    • b) An elongated pointed flame with concave sides, see Figure 6 (A flame).
    • c) The pointed tip has just disappeared, and a slightly blunted flame appears, see Figure 6 (B flame). Near the tip close to the true flame, a jagged amorphous luminous flame sometimes appears.
    • d) A flame with a relatively smooth, rounded tip, see Figure 6 (C flame). Measure and record the B flame height, to the nearest 0.5 mm.
  • 10.2.4 In order to eliminate parallax, the observer's eye should be inclined to one side of the center line, so that the reflected image can be seen on one side of the white vertical line of the scale, and the flame itself can be seen on the other side. The two readings should be the same value.
  • 10.2.5 As specified in 10.2.3, repeat the observation of the flame shape 3 times; if the variation of the measured values exceeds 1.0 mm, use a new test sample and replace the wick and repeat the test.
  • 10.2.6 Remove the oil reservoir from the smoke point lamp (manual), rinse it with n-heptane, and then blow it dry with air so that it can be reused.
• 10.3 Automatic instrument test procedure:
  • 10.3.1 Place the oil reservoir on the instrument's transport platform, see step 1, step 2 and step 3 in Figure 8.
  • 10.3.2 Input the test sample details and the atmospheric pressure at that time, then start the test. For more details, refer to the instrument manufacturer's user manual.
  • 10.3.3 The oil reservoir can automatically rise into the smoke point lamp (automatic) and be ignited.
  • 10.3.4 Automatically adjust the oil reservoir until the flame height is about 10 mm, and burn stably for 5 min.
  • 10.3.5 After a combustion stabilization time of 5 min, the oil reservoir automatically rises until smoke appears, and then slowly lowers. The instrument software analyzes the flame image from the digital camera. According to the requirements of 10.2.3 c), automatically find the shape consistent with the B flame. Measure and record the height of the B flame, to the nearest 0.1 mm. The oil reservoir transport platform slowly lowers the oil reservoir until the initial position, and the flame is automatically extinguished.
  • 10.3.6 As specified in 10.2.3, the instrument repeats the observation of the flame shape three times for the smoke point value, as the measured value of the smoke point of the test sample. If the variation of the measured values exceeds 1.0 mm, the instrument will prompt the operator that a new test sample should be used and a wick should be replaced to repeat the test.
  • 10.3.7 Remove the oil reservoir from the transport platform, first clean it with n-heptane, and then blow it dry with air for reuse.

9. Qualitative and Quantitative and Calculation Formulas

• 11.1 Manual instrument: Calculate the smoke point of the test sample (h) according to formula (2), to the nearest 0.1 mm: h = L × f ………………(2) Where: h ———Smoke point of the test sample, to the nearest 0.1, in millimeters (mm); L ———Average of three independent readings of the smoke point, to the nearest 0.1, in millimeters (mm); f ———Calibration coefficient (see 9.1.3), to the nearest 0.01.
• 11.2 Automatic instrument: The instrument automatically calculates the smoke point value according to 11.1.
• For the calculation formula of the calibration coefficient f, see 9.1.3 formula (1).

10. Precision

12.1 Overview

The precision of this document was obtained by testing 15 different blind samples on 11 manual instruments and 13 automatic instruments respectively. The 11 manual instruments and the 13 automatic instruments respectively belong to different laboratories. 12.2, 12.3, 12.4 specify the reliability requirements for judging test results (95% confidence level). The precision data for manual instruments in this document apply to atmospheric pressure 70 kPa～102 kPa, and the precision data for automatic instruments apply to atmospheric pressure 75 kPa～102 kPa; for smoke point determinations at other pressures, the precision may be used for reference.

12.2 Manual instrument (see Table 2 and Figure 9)

• 12.2.1 Repeatability (r): The difference between two consecutive test results obtained by the same operator, in the same laboratory, using the same instrument, according to the same method, on the same test sample shall not exceed the value calculated by formula (3): r = 0.06840(X1 + 16) ………………(3) Where: X1 ———Arithmetic mean of two replicate test results, in millimeters (mm).
• 12.2.2 Reproducibility (R): The difference between two single, independent test results obtained by different operators, in different laboratories, using different instruments, according to the same method, on the same test sample shall not exceed the value calculated by formula (4): R = 0.09363(X2 + 16) ………………(4) Where: X2 ———Arithmetic mean of two single, independent test results, in millimeters (mm).

12.3 Automatic instrument (see Table 2 and Figure 9)

• 12.3.1 Repeatability (r): For the same operator, in the same laboratory, using the same instrument, following the same method, testing the same sample, the difference between two consecutive test results shall not exceed the value calculated by formula (5): r = 0.02231X1 ………………(5) Where: X1 ——— arithmetic mean of two replicate test results, in millimeters (mm).
• 12.3.2 Reproducibility (R): For different operators, in different laboratories, using different instruments, following the same method, testing the same sample separately, the difference between two single, independent test results shall not exceed the value calculated by formula (6): R = 0.01651(X2 + 30) ………………(6) Where: X2 ——— arithmetic mean of two single, independent test results, in millimeters (mm).

Table 2 Typical precision values

12.4 Bias

• 12.4.1 Because the smoke point is defined solely by this test method, this test method has no bias.
• 12.4.2 There is a relative bias between the manual procedure and the automatic procedure. Across the entire smoke point range, the bias has an approximately consistent ratio. The correlation of the corresponding bias is given in formula (7): (A + 16) = (M + 16) / 1.016 ………………(7) Where: A ——— result value measured by the automatic procedure, in millimeters (mm); M ——— result value measured by the manual procedure, in millimeters (mm).
• 12.4.3 There is no bias correction for results measured with the automatic instrument.

11. Report

The report shall include at least the following:

• a) Sample name, number;
• b) Test instrument, manual or automatic;
• c) Test result, accurate to 0.1 mm;
• d) Atmospheric pressure, accurate to 0.1 kPa;
• e) Standard used;
• f) Abnormal phenomena observed;
• g) Test date.

12. Normative references

• GB/T 4756 Petroleum liquids — Manual sampling
• GB/T 12807—2021 Laboratory glassware — Graduated pipettes
• GB/T 12808—2015 Laboratory glassware — One-mark pipettes
• GB/T 27867 Petroleum liquids — Automatic pipeline sampling
• NB/SH/T 0843 Evaluation of test methods in the petrochemical industry — Statistical techniques
• SH/T 0635 Sampling method for liquid petroleum products (semi-automatic method)
• GB/T 4016—2019 Petroleum products terminology (reference document)

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Q&A