GB/T 3535-2025 Determination of Pour Point of Petroleum Products

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Card type: Test method

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

• Standard number: GB/T 3535—2025
• Chinese title: Determination of Pour Point of Petroleum Products
• English title: Determination of pour point for petroleum products
• Adoption relationship: Modified adoption of ISO 3016: 2019 "Petroleum and related products from natural or synthetic sources—Determination of pour point" (MOD)
• Replacement relationship: Replaces GB/T 3535—2006
• Publication/implementation: Published on 2025-10-05, implemented on 2026-05-01
• Custodian: National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280)
• First published in 1983, first revision in 2006, this is the second revision

2. Scope of application and non-applicability

• Applicable to: determination of pour point of petroleum products; also describes the test method for determining the (minimum) pour point of fuel oils, heavy lubricant base oils, and products containing residual fuel components.
• Automatic method applicable to: determination of pour point of petroleum products where the cooling program is the same as the manual method and the measurement interval is 3 ℃; its precision is applicable to lubricating oils, lubricant base oils, and middle distillate fuels.
• Not applicable to: determination of pour point of crude oil (explicitly specified as not applicable).

3. Method principle

After preheating, the sample is cooled at a specified rate, and the fluidity of the sample is checked every 3 ℃. The lowest temperature at which the sample is observed to pour or flow is recorded as the pour point. (See Chapter 4)

4. Reagents and materials (purity / preparation)

• Appendix B (informative) Common reagents and mixed refrigerants:
  • B.1 Acetone: industrial grade, used for cooling baths, required to leave no stain when completely evaporated.
  • B.2 Dry ice: carbon dioxide (solid).
  • B.3 Ice: commercial grade, used for cooling baths.
  • B.4 Naphtha: commercial or technical grade, used for cooling baths.
  • B.5 Sodium chloride crystals: commercial or industrial grade, used for cooling baths.
  • B.6 Sodium sulfate: if needed, reagent grade anhydrous sodium sulfate should be used.
  • B.7 Ethanol: commercial or industrial grade ethanol, used for cooling baths.
  • B.8 Methanol: commercial or industrial grade methanol, used for cooling baths.
  • B.9 Mixed refrigerants: as shown in Table B.1, generally used to maintain bath temperature.
• Table B.1 Common mixed refrigerants and bath temperatures:
  • Ice-water mixture: 0 ℃±1.5 ℃
  • Crushed ice and sodium chloride crystals, or acetone or naphtha or methanol or ethanol, with dry ice added, to reach the required temperature: −18 ℃±1.5 ℃
  • Acetone or naphtha or methanol or ethanol, with dry ice added, to reach the required temperature: −33 ℃±1.5 ℃
  • Acetone or naphtha or methanol or ethanol, with dry ice added, to reach the required temperature: −51 ℃±1.5 ℃
  • Acetone or naphtha or methanol or ethanol, with dry ice added, to reach the required temperature: −69 ℃±1.5 ℃
• Wiping liquid: the source text in Note 7.1.7 gives examples of ethanol or methanol (close to the cooling bath temperature).

5. Apparatus and equipment

5.1 Manual pour point tester

• 5.1.1 Test tube: flat-bottomed, cylindrical transparent glass; outer diameter 33.2 mm~34.8 mm, height 115 mm~125 mm, inner diameter 30.0 mm~32.4 mm, wall thickness not greater than 1.6 mm; a long etched line is marked at 54 mm±3 mm from the inner bottom of the test tube to indicate a content volume of 45 mL±1 mL.
• 5.1.2 Temperature measuring device (meeting one of the following is sufficient):
  • a) Contact digital thermometer (DCT), which shall meet the requirements of A.1 in Appendix A.
  • b) Liquid-in-glass thermometer: partial immersion type, which shall meet the requirements of A.2; the thermometer shall be checked before testing, and the accuracy shall be within the range of ±1 ℃.
• 5.1.3 Cork stopper: for use with the test tube, with a hole in the center for mounting the temperature measuring device.
• 5.1.4 Sleeve: flat-bottomed, cylindrical metal, leak-proof, cleanable; inner diameter 44.2 mm~45.8 mm, wall thickness about 1 mm, height 115 mm±3 mm; it shall be able to maintain an upright position in the cooling bath, the part above the cooling bath liquid level shall not exceed 25 mm, and it shall be cleanable.
• 5.1.5 Disc: made of cork or felt, about 6 mm thick, with a diameter matching the inner diameter of the sleeve.
• 5.1.6 Gasket: made of rubber, leather, or other suitable material; ring-shaped, about 5 mm thick, with some elasticity, shall fit tightly against the outer wall of the test tube and remain loose with the inner wall of the sleeve; shall have sufficient hardness to maintain shape. Its purpose is to prevent direct contact between the test tube and the sleeve.
• 5.1.7 Cooling bath: capable of firmly fixing the sleeve in a vertical position at the specified temperature; the bath temperature can be obtained by refrigeration or a suitable mixed refrigerant.
• 5.1.8 Timer: the maximum error in measuring 30 s shall not exceed 0.2 s.

5.2 Automatic pour point tester

• 5.2.1 Automatic pour point tester: composed of a computer control system, cooling system, monitor, sensor, mechanical arm for lifting and tilting the pour point tube (optional), etc.; the computer control system can control 1 or more independent test units; the monitor shall be able to continuously monitor the sample temperature; the sensor shall be able to detect slight movement of the sample during tilting.
• 5.2.2 Pour point tube: transparent cylindrical glass product, flat bottom, outer diameter about 32 mm, height about 120 mm, shall have an etched line to indicate a sample height of about 45 mL.
• 5.2.3 Pour point tube sleeve: cylindrical metal product, flat bottom, inner diameter about 45 mm, height about 115 mm.
• 5.2.4 Temperature probe: capable of measuring in the range of −80 ℃~70 ℃, resolution 0.1 ℃; the temperature probe shall be inside the pour point test tube, and the top of the temperature sensing area shall be immersed below the sample surface.
• 5.2.5 Cooling system: internal cooling system or external cooling system equipped with a circulation pump, capable of maintaining the bath temperature to meet the requirements of Table 1.

Appendix A (normative) Technical specifications for temperature measuring devices

• A.1 Electronic temperature measuring device: DCT shall meet the technical specifications in Table A.1.
  • Nominal temperature range (tolerance not greater than 0.5 ℃): high pour point −38 ℃~+50 ℃; low pour point −80 ℃~+20 ℃; melting point 32 ℃~127 ℃
  • Scale division: not greater than 0.1 ℃
  • Accuracy: ±0.5 K (±0.5 ℃)
  • Sensor type: platinum resistance thermometer (PRT), thermistor
  • Sensor sheath: outer diameter not greater than 4.2 mm
  • Sensor length: less than 10 mm
  • Immersion depth: less than 40 mm
  • Sample immersion depth: sheath tip immersed to 10 mm~15 mm below the sample meniscus
  • Response time: not greater than 4 s
  • Measurement drift: less than 0.5 K per year (0.5 ℃)
  • Calibration error: less than 0.5 K within the expected applicable range (0.5 ℃)
  • Calibration range: consistent with the operating temperature range
  • Calibration data: 4 data points evenly distributed within the calibration range consistent with the operating range; calibration data will be included in the calibration report
  • Calibration report: issued by a calibration laboratory with temperature calibration capability, traceable to a national calibration laboratory or metrology standards organization
  • Table A.1 footnotes: a If calibration and accuracy requirements are met, the nominal temperature range temperatures may differ from the values shown; b Accuracy is the combined accuracy of the DCT unit (i.e., display and sensor); c The sensor sheath is the tube that holds the sensing element, and this value is the outer diameter of the sheath section containing the sensor element; d The physical length of the temperature sensing element; e Response time is the time percentage required for a step change in temperature of DCT response, with the step change evaluated from 20 ℃±5 ℃ (air) to 77 ℃±5 ℃ (water circulating through the sensor at a velocity of 0.9 m/s±0.09 m/s).
  • Other notes: When the DCT display is mounted at the end of the probe sheath, the test tube inserted into the probe will be unstable; it is recommended that the probe length be between 15 cm~30 cm, and inserting a 5 cm long stopper with low thermal conductivity into the test tube (about half of which is inserted into the test tube) will improve stability. When using PRT for measurements below −40 ℃, it may be necessary to use a 1 000 Ω sensor to obtain accurate measurements. The DCT calibration drift should be checked at least annually; by measuring the ice point or checking against a reference thermometer in a constant-temperature bath at the specified immersion depth, to ensure that the measurement drift requirements specified in Table A.1 are met.
• A.2 Liquid-in-glass thermometer: partial immersion type, which shall meet the technical specifications in Table A.2.
  • Thermometer for low cloud point and low pour point: temperature range −80~20 ℃; immersion depth 76 mm; graduation value 1 ℃; long line interval 5 ℃; numbered scale interval 10 ℃; indication tolerance 1 ℃ (when ≥−33 ℃), 2 ℃ (when <−33 ℃); safety bulb allowed to be heated to 60 ℃; total length 230 mm±5 mm; stem outer diameter 6 mm~8 mm; sensing bulb length 7 mm~10 mm; sensing bulb outer diameter 5.0 mm~stem outer diameter; distance from bottom of sensing bulb to graduation line −70 mm; scale range length 100 mm~120 mm; distance from bottom of sensing bulb to graduation line (℃) −70; distance 100~120 mm; scale range length 70~100 mm (Note: the data arrangement of this row in the original table A.2 has source-text extraction misalignment, requires confirmation against the source standard (source-text extraction))
  • Thermometer for high cloud point and high pour point: temperature range −38~50 ℃; immersion depth 108 mm; graduation value 1 ℃; long line interval 5 ℃; numbered scale interval 10 ℃; indication tolerance 0.5 ℃; safety bulb allowed to be heated to 100 ℃; total length 230 mm±5 mm; stem outer diameter 6 mm~8 mm; sensing bulb length 7 mm~10 mm; sensing bulb outer diameter 5.5 mm~stem outer diameter; distance from bottom of sensing bulb to graduation line −38 ℃; distance 120~130 mm; scale range length 65~85 mm
  • Thermometer for melting point: temperature range 32~127 ℃; immersion depth 79 mm; graduation value 0.2 ℃; long line interval 1 ℃; numbered scale interval 2 ℃; indication tolerance 0.2 ℃; safety bulb allowed to be heated to 150 ℃; total length 380 mm±5 mm; stem outer diameter 6 mm~8 mm; sensing bulb length 18 mm~28 mm; sensing bulb outer diameter 5.0 mm~6.0 mm; distance from bottom of sensing bulb to graduation line 32 ℃; distance 105~115 mm; scale range length 200~240 mm
  • Note 1: The emergent stem temperature over the entire temperature range is 21 ℃.
  • Note 2: Glass liquid thermometers that have the temperature ranges listed in Table A.3 and meet the requirements of GB/T 514—2005 all satisfy the technical conditions in Table A.2.
  • Glass liquid thermometers meeting the requirements in Table A.3: thermometer for high cloud point and high pour point −38~50 ℃, number GB⁃37; thermometer for low cloud point and low pour point −80~20 ℃, number GB⁃36; thermometer for melting point 32~127 ℃, number GB⁃35.

6. Recommended operating conditions

• Cooling/bath temperature program (bath temperature and specimen temperature ranges in Table 1):
  • Bath number 1: bath temperature set at 48 ℃±1.5 ℃ or 12 ℃ above the expected pour point; specimen temperature range: heat to at least 45 ℃ or 9 ℃ above the expected pour point (choose the higher)
  • Bath number 2: bath temperature set at 24 ℃±1.5 ℃; specimen temperature range 27 ℃
  • Bath number 3: bath temperature set at 0 ℃±1.5 ℃; specimen temperature range 27 ℃~9 ℃
  • Bath number 4: bath temperature set at −18 ℃±1.5 ℃; specimen temperature range 9 ℃~−6 ℃
  • Bath number 5: bath temperature set at −33 ℃±1.5 ℃; specimen temperature range −6 ℃~−24 ℃
  • Bath number 6: bath temperature set at −51 ℃±1.5 ℃; specimen temperature range −24 ℃~−42 ℃
  • Bath number 7: bath temperature set at −69 ℃±1.5 ℃; specimen temperature range −42 ℃~−60 ℃
• Automatic method: use 3 ℃ as the test interval temperature; the time for the bath temperature to adjust from one level to the next lower level should not exceed 200 s (see 7.2.5).
• Manual method observation interval: check fluidity every 3 ℃ (see Chapter 4, 7.1.7).

7. Sampling and specimen preparation

• Sampling: unless otherwise specified, sampling shall be carried out in accordance with the provisions of GB/T 4756 or GB/T 27867 (see Chapter 6).
• Manual method specimen preparation (7.1.1): pour the specimen into the test tube (5.1.1) up to the graduation line; if necessary, the specimen may first be heated in a water bath until fluid, then poured into the test tube. If it is known that the specimen has been heated above 45 ℃ within 24 h before the start of the test, or its heating history is unknown, it must be left at room temperature for 24 h before testing.
• Automatic method specimen preparation (7.2.2): pour the specimen into the pour point tube (5.2.2) up to the graduation line; if necessary, it may first be heated in a water bath until fluid, then poured into the pour point tube. If it is known that the specimen has been heated above 45 ℃ within 24 h before the start of the test, or its heating history is unknown, it must be left at room temperature for 24 h before testing. Note: residual fuel oils are relatively sensitive to thermal history; for pretreatment of such samples see 7.1.1; however, the precision statistics of the automatic method in this document do not include residual fuel oil samples.
• Installation of temperature measuring device (7.1.2): stopper the test tube with a cork inserted with a thermometer for high cloud point and high pour point (see A.2) or a contact digital thermometer with a nominal temperature range of high pour point (see A.1); if the expected pour point of the specimen is higher than 36 ℃, use a melting point temperature measuring device (5.1.2), such as the glass liquid thermometer with thermometer number GB⁃35 in GB/T 514—2005 (see A.2) or a contact digital thermometer with a nominal temperature range of melting point (see A.1). Adjust the position of the cork and temperature measuring device so that the cork tightly stoppers the test tube, requiring the temperature measuring device and the test tube to be on the same axis, and the temperature measuring device to be immersed at an appropriate depth below the specimen liquid surface. For glass liquid thermometers, the starting point of the thermometer capillary should be immersed 3 mm below the specimen liquid surface. For contact digital thermometers, the tip of the probe should be immersed 10 mm~15 mm below the specimen liquid surface.

8. Analytical procedure

7.1 Manual method

• 7.1.3 Pretreat the specimen in the test tube according to 7.1.4 or 7.1.5.
• 7.1.4 Treatment of specimens with pour point higher than −33 ℃:
  • a) Without stirring, place the specimen in a bath maintained at 12 ℃ above the expected pour point, but at least 48 ℃, and heat the specimen to 45 ℃ or 9 ℃ above the expected pour point (choose the higher).
  • b) Transfer the test tube to a bath maintained at 24 ℃±1.5 ℃ and begin observing the pour point. If a liquid bath is used, ensure the liquid level is between the test tube graduation line and the upper surface of the test tube.
  • c) When the specimen reaches 9 ℃ above the expected pour point (estimated as a multiple of 3 ℃), begin observing the fluidity of the specimen as specified in 7.1.7.
  • d) If the specimen is still fluid when its temperature reaches 27 ℃, carefully remove the test tube from the bath, wipe the outer surface of the test tube with a clean cloth moistened with wiping liquid, then place the test tube as specified in 7.1.6 in a cold bath (5.1.7) at 0 ℃. Observe the fluidity of the specimen as specified in 7.1.7, and cool according to the procedure specified in 7.1.8.
• 7.1.5 Treatment of specimens with pour point of −33 ℃ and below −33 ℃:
  • a) Without stirring, heat the specimen in a bath at 48 ℃±1.5 ℃ to 45 ℃, then place it in a bath at 24 ℃±1.5 ℃ to cool to 27 ℃.
  • b) If a liquid bath is used, ensure that the liquid level is between the test tube graduation line and the upper surface of the test tube. When the sample temperature reaches 27 ℃, if a glass liquid thermometer is used, remove the thermometer for high cloud point and high pour point, replace it with the thermometer for low cloud point and low pour point, place the test tube into the cold bath, and cool according to the procedure specified in 7.1.8.
• 7.1.6 Ensure that the inner walls of the disc (5.1.5), gasket (5.1.6), and sleeve (5.1.4) are clean and dry, and place the disc at the bottom of the sleeve. Before inserting the test tube, the disc and sleeve should be placed in the cold bath (5.1.7) for at least 10 min. Fit the gasket around the outer wall of the test tube, about 25 mm from the bottom, and insert the test tube into the sleeve. Except for the 24 ℃ bath, the test tube must not be placed directly into the cooling medium.
• 7.1.7 Observe the fluidity of the sample:
  • a) Starting from the first observation temperature, for every decrease of 3 ℃, remove the test tube from the bath or sleeve (depending on actual use), tilt the test tube sufficiently to determine whether the sample flows. Usually, the entire operation of removing the test tube, wiping it, and returning the test tube to the cold bath requires no more than 3 s.
  • b) Starting from the first observation of the sample's fluidity, for every decrease of 3 ℃ in temperature, observe the fluidity of the sample. After the sample has cooled sufficiently to form paraffin crystals, special care must be taken not to stir the lumps in the sample, nor to move the thermometer within the sample. Agitating the porous network of crystals in the paraffin can lead to low or erroneous results. Note: At low temperatures, condensed water mist can hinder observation; a clean cloth moistened with a wiping liquid (e.g., ethanol or methanol) at a temperature close to that of the cold bath can be used to wipe the test tube to remove water mist on the outer surface.
  • c) When the test tube is tilted and the sample does not flow, immediately place the test tube in a horizontal position 5 s, start timing with a timer (5.1.8), and carefully observe the sample surface. If the sample shows any movement, immediately return the test tube to the cold bath or sleeve (depending on actual use), and when the temperature has decreased by another 3 ℃, re-observe the fluidity of the sample.
  • d) Continue in this manner until, with the test tube placed in a horizontal position 5 s, the sample in the test tube does not move; record the thermometer reading observed at this time.
• 7.1.8 If the sample still flows when the temperature reaches 27 ℃, transfer the test tube to a bath with a bath temperature of 0 ℃±1.5 ℃, and as the sample temperature continues to decrease, transfer the test tube to the next lower-temperature cold bath in the order listed in Table 1.
• 7.1.9 If a no-flow point has already been observed on the first tilt, discard the result, replace with a new sample, set a higher expected pour point, and repeat the determination according to the procedure described in 7.1.1~7.1.8.
• 7.1.10 For samples whose specification pour point value is not a multiple of 3 ℃, the following may also be used: start checking the fluidity of the sample when the sample temperature is 9 ℃ above the specification pour point value, then observe the sample at intervals of 3 ℃ according to the procedure described in 7.1.7 and 7.1.8, until the specification value of the sample. Report whether the sample passes or fails the specification value.
• 7.1.11 For fuel oils, heavy lubricating base oils, and residual fuel oils, the result obtained by the procedure described in 7.1.1~7.1.8 is the upper (maximum) pour point of the sample. If the lower (minimum) pour point of the sample needs to be determined, the sample may first be heated to 105 ℃ with stirring, then poured into the test tube, and determined according to the procedure described in 7.1.2~7.1.8.

7.2 Automatic method

• 7.2.1 Prepare the instrument according to the instrument manufacturer's operating instructions.
• 7.2.3 Sample pretreatment:
  • a) When the expected pour point of the sample is higher than −33 ℃, place the sample without stirring into a bath maintained at 12 ℃ above the expected pour point, but at least 48 ℃, and heat the sample to 45 ℃ or 9 ℃ above the expected pour point (whichever is higher).
  • b) When the expected pour point of the sample is −33 ℃ and below −33 ℃, heat the sample without stirring in a bath at 48 ℃ to 45 ℃.
• 7.2.4 According to the instrument manufacturer's instructions, assemble the pour point tube onto the automatic pour point tester, use 3 ℃ as the test interval temperature, input the expected pour point temperature, and start the test according to the instrument's operating instructions.
• 7.2.5 During the pour point determination, the instrument should automatically adjust the bath temperature according to the sample temperature in accordance with the cooling program in Table 1; the time for the bath temperature to adjust from one level to the next lower level should not exceed 200 s.
• 7.2.6 When the sample temperature is 9 ℃ above the expected pour point, the instrument begins to tilt the pour point tube in the specified manner (direct tilting or lifting by a mechanical arm and then tilting), and detects whether the sample moves through an optical system; this operation process should be controlled within 5 s. If movement of the sample is observed when the pour point tube is tilted, the pour point tube should be returned to the cold bath and restored to the vertical position. Starting from the first observation of the sample's fluidity, for every decrease of 3 ℃ in temperature, the instrument should repeat the above operation until no movement of the sample is detected when the pour point tube is tilted horizontally 5 s; the corresponding temperature at this time is the no-flow point temperature. The no-flow point temperature plus 3 ℃ is the pour point of the sample. After the pour point is determined, the instrument will display the pour point result and reheat the sample.
• 7.2.7 If a no-flow point has already been detected on the first tilt, discard the result, replace with a new sample, set a higher expected pour point, and repeat the determination according to the procedure described in 7.2.2~7.2.6.
• 7.2.8 Record or print the final test result displayed on the automatic pour point tester as the pour point of the sample.

9. Qualitative and quantitative determination and calculation formulas

• 8.1 For the manual method, the results recorded in 7.1.7 d) and 7.1.11 should be added to 3 ℃ to serve as the pour point or lower pour point of the sample (depending on actual use), with the result accurate to 1 ℃.
• 8.2 For the automatic method, the pour point of the sample should be reported according to the requirements of 7.2.8, with the result accurate to 1 ℃.
• 8.3 In case of dispute, the pour point test result of the manual method shall prevail for arbitration testing.

10. Precision

9.1 Precision of the manual method

• 9.1.1 General: The reliability of test results should be judged according to 9.1.2.1, 9.1.2.2, 9.1.3.1, and 9.1.3.2 (confidence level of 95%).
• 9.1.2 Lubricating oils:
  • 9.1.2.1 Repeatability: In the same laboratory, by the same operator using the same instrument, according to the same method, the difference between two consecutive test results on the same sample shall not exceed 6 ℃.
  • 9.1.2.2 Reproducibility: In different laboratories, by different operators using different instruments, according to the same method, the difference between two single, independent test results on the same sample shall not exceed 9 ℃.
• 9.1.3 Middle distillate fuels and residual fuel oils:
  • 9.1.3.1 Repeatability: In the same laboratory, by the same operator using the same instrument, according to the same method, the difference between two consecutive test results on the same sample shall not exceed 3 ℃.
  • 9.1.3.2 Reproducibility: In different laboratories, by different operators using different instruments, according to the same method, the difference between two single, independent test results on the same sample shall not exceed 9 ℃.

9.2 Precision of the automatic method

• 9.2.1 General: The precision data of the automatic method come from test results of 10 laboratories on 17 different types of samples. The samples include: gasoline engine oils, diesel engine oils, heavy-duty gear oils, industrial enclosed gear oils, turbine oils, air compressor oils, lubricating base oils, electric vehicle reducer oils, middle distillate fuels, and other types of products, with pour point range from −54 ℃~−6 ℃. The test results were determined through interlaboratory statistical analysis according to GB/T 6683.1. The reliability of test results should be judged according to 9.2.2 and 9.2.3 (confidence level of 95%).
• 9.2.2 Repeatability: In the same laboratory, by the same operator using the same instrument, according to the same method, the difference between two consecutive test results on the same sample shall not exceed 3 ℃.
• 9.2.3 Reproducibility: In different laboratories, by different operators using different instruments, according to the same method, the difference between two single, independent test results on the same sample shall not exceed 9 ℃.

11. Report

The test report shall include at least the following contents (Chapter 10):

• a) Complete information of the product tested;
• b) Indicate reference to this document, e.g., GB/T 3535—2025;
• c) Test results (see Chapter 8);
• d) Any differences from the test procedure of this document as agreed or otherwise specified shall be noted (see Chapter 7);
• e) Test date;
• f) Indicate whether the manual method or automatic method was used for the determination test.

12. Normative references

• Normative references (Chapter 2):
  • GB/T 4756 Petroleum liquids — Manual sampling (GB/T 4756—2015, ISO 3170:2004, MOD)
  • GB/T 27867 Petroleum liquids — Automatic pipeline sampling (GB/T 27867—2011, ISO 3171:1988, IDT)
• Bibliography:
  • [1] GB/T 514—2005 Specification for glass liquid thermometers for petroleum product testing
  • [2] GB/T 6683.1 Petroleum and related products — Determination of precision of measurement methods and results — Part 1: Determination of precision data of test methods

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 reference for questions and answers