GB/T 13287-1991 Liquefied petroleum gas volatility determination method

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 name / English name / replacement relationship

• Standard number: GB/T 13287-91
• Chinese name: Liquefied petroleum gas volatility determination method
• English name (original text): Lguefled, petroleum gases Determination of volatility (requires confirmation against the source standard (source-text extraction), suspected to be Liquefied petroleum gases — Determination of volatility)
• Replacement relationship: not provided in the available source
• Reference adoption: American Society for Testing and Materials standard ASTM D1837-86 "Standard Test Method for Volatility of Liquefied Petroleum Gases" (see additional notes)
• Approval/implementation: approved by the State Bureau of Technical Supervision 1991-12-09, implemented on 1992-10-01

2. Scope of application and non-applicability

• This standard specifies a method for determining the volatility of liquefied petroleum gas.
• Applicable to propane type, propane-butane mixture type and butane type liquefied petroleum gas.
• The volatility referred to in this standard is expressed by the temperature when the test sample is vaporized at 95% (V/V); the presence of low-volatility hydrocarbon compounds means that this temperature will increase.
• The test results can be used to predict the approximate content of higher boiling point components in various types of liquefied petroleum gas.
• Non-applicable scope: not provided in the available source.
• Note: Liquefied petroleum gas is extremely volatile and flammable; relevant safety issues must be noted during operation.

3. Method principle

Collect liquefied petroleum gas cooled by a coolant in a vaporization tube 100 mL, vaporize it under specified conditions, and determine the temperature at which the liquefied petroleum gas vaporizes 95% (V/V). The vaporization temperature is affected by changes in atmospheric pressure; measurements under non-standard conditions require atmospheric pressure correction.

4. Reagents and materials (purity / preparation)

• 5.1 Acetone: analytical reagent.
• 5.2 95% Ethanol: analytical reagent.
• 5.3 Activated carbon: 20~30 mesh.
• 4.6 Coolant: for preparation details see GB 510; liquefied petroleum gas taken from the same sample container may also be used, but safety must be noted; there must be no open flame or electric spark in the test site or exhaust duct, and static electricity must also be prevented.

5. Instruments and equipment

• 4.1 Vaporization tube: conical centrifuge tube, as shown in Figure 1; made of heat-resistant glass, the taper of the tube tip must be uniform; for technical specifications of the centrifuge tube see GB 6533.
• 4.2 Tube rack: used to fix the vaporization tube in a vertical position.
• 4.3 Water bath: depth 40 mm, capable of maintaining water temperature in the range 15~20 °C.
• 4.4 Thermometer: see Appendix A; when in use, it is sheathed in a metal sleeve.
• 4.5 Sample precooler (see Figure 2)
  • 4.5.1 Cooler: a Dewar flask with inner diameter 64 mm and depth 292 mm.
  • 4.5.2 Cooling coil: made of soft copper tubing with outer diameter 4.8 mm and length 6 m, wound into a spiral tube with an outer diameter of at least 54 mm hollow; adjacent turns must be close together; the outlet end of the cooling coil passes upward through the center of the spiral tube, so that the wound spiral tube fits closely against the inner wall of the cooler; the top of the cooling coil must be lower than the cooler 25 mm and must not be exposed above the coolant liquid surface; the outlet of the cooling coil is connected to a 3.2 mm needle valve, and the length from the outlet end must not exceed 76 mm.
• Appendix A Thermometer specifications (supplementary element):
  • Range: -50~5.0 °C
  • Immersion depth: 35 mm
  • Graduation: 0.2 °C
  • Numbered graduations: 2.0 °C
  • Error: 0.2 °C
  • Expansion chamber allowed to be heated to: 65 °C
  • Total length: 299~305 mm
  • Rod diameter: 6.5~8.0 mm
  • Bulb length: 15~20 mm
  • Bulb diameter: 6.0~7.0 mm
  • Distance from bulb bottom to -50 °C graduation: 50~75 mm
  • Length of graduated portion: 169~215 mm
• Figure 1 Vaporization tube labels: 1— sheathed thermometer; 2— slit cork.
• Figure 2 Precooler labels: 1— cooling coil; 2— cooler; 3— inlet valve; 4— outlet valve.
• Numbers beside Figure 1 (source-text extraction suspected to be dimension annotations, requires confirmation against the source standard (source-text extraction)): 36.00–37.75; 2; 7–10; 292–300; 195–203; 82~90; 64.

6. Recommended operating conditions

• Water bath temperature: 15~20 °C (4.3, 6.3).
• Immersion depth of vaporization tube inserted into water bath: at the 1.5 mL graduation (6.3).
• Butane and propane-butane mixture type samples: if the vaporization temperature is lower than -12 °C, direct vaporization in air is allowed until the temperature reaches -12 °C, then insert into a 15~20 °C water bath for vaporization (6.3).
• Propane type samples: allow the sample vaporization tube with the sheathed thermometer inserted to vaporize directly in the atmosphere; when frost appears at the graduation of the vaporization tube, it is allowed to remove it with a cotton ball dipped in acetone or ethanol (6.4).
• When the thermometer is used, it should be sheathed in a metal sleeve (4.4); do not remove the metal sleeve from the sheathed thermometer during the test (6.2 note).

7. Sampling and sample preparation

• 6.1 According to the provisions of SY 2084, collect a sufficient amount of representative sample; store the liquefied petroleum gas sample at room temperature.
• 6.2 Sampling:
  • Pour coolant into the cooler and immerse the cooling coil in it.
  • Connect the inlet of the cooling coil to the sampling valve of the liquefied petroleum gas sampler using a short tube of 6.4 mm (or a slightly larger short tube).
  • Open the sampling valve and the 3.2 mm needle valve at the outlet of the cooling coil, and purge the sampling tube and cooling coil.
  • Pass the sample through the cooling coil into the vaporization tube.
  • Discard the first sample.
  • Add 2~3 particles of activated carbon to the vaporization tube, then inject 100 mL of fresh liquid sample through the cooling coil.
  • Carefully insert the precooled sheathed thermometer into the vaporization tube, with the insertion depth as low as possible, and fix the sheathed thermometer in the vaporization tube with a slit cork.
• 6.2 Note: Do not remove the metal sleeve from the sheathed thermometer during the test. Before the test, for each vaporization tube, place the sheathed thermometer at the bottom of the vaporization tube, accurately inject 5 mL 20 °C of distilled water, observe the liquid level of the distilled water in the vaporization tube, and mark it. During the determination, place the sheathed thermometer in the same position, and use the same sample liquid level as the volume of 5% (V/V) residue.

8. Analytical procedure

• 6.3 Vaporization of butane and propane-butane mixture type liquefied petroleum gas samples: if the vaporization temperature of the sample is lower than -12 °C, direct vaporization in air is allowed until the temperature reaches -12 °C, then vertically insert the vaporization tube with the sheathed thermometer inserted into a 15~20 °C water bath, with the immersion depth at the 1.5 mL graduation, to allow vaporization.
• 6.4 Vaporization of propane type liquefied petroleum gas products: allow the sample vaporization tube with the sheathed thermometer inserted to vaporize directly in the atmosphere; when frost appears at the graduation of the vaporization tube, it is allowed to remove it with a cotton ball dipped in acetone or ethanol.
• 6.5 Temperature reading: when the sheathed thermometer is inserted in the vaporization tube and the liquid volume in the vaporization tube is equivalent to the position corresponding to 5 mL 20 °C of distilled water, read the temperature according to the requirements of clause 6.3 and clause 6.4, and record the temperature of the sample.
• 6.6 Temperature correction: remove the sheathed thermometer from the vaporization tube, place it in an ice-water bath up to the immersion point, and when a stable reading is obtained, carefully read the temperature. If the temperature is lower than 0 °C, add the amount by which it is lower to the test temperature reading; if the temperature is higher than 0 °C, subtract the amount by which it is higher from the test temperature reading. Any thermometer whose deviation exceeds 0.6 °C must not be used.
• 6.6 Note: When the thermometer reading in an ice-water bath is too high, it indicates that the mercury-thallium column has broken; in this case, the thermometer may be slowly heated in a hot water bath to make the broken column rise to the expansion chamber; when the mercury-thallium column remains in the expansion chamber, the bottom of the thermometer may be gently tapped on a hard and elastic surface until the liquid connects to the connecting line. When the thermometer reading in an ice-water bath is too low, it indicates that liquid remains in the expansion chamber; in this case, the thermometer may be warmed to allow the liquid to enter the expansion chamber, and then tapped and corrected as above.

9. Qualitative and quantitative determination and calculation formulas

• Volatility is expressed by the temperature when the test sample is vaporized at 95% (V/V) (Chapter 1).
• Test result correction (Chapter 7):
  • 7.1 For the thermometer reading at the boiling point of 95% (V/V) [5% (V/V) residue], make the following correction.
  • 7.1.1 In the propane type liquefied petroleum gas vaporization test: when the atmospheric pressure in the test area is lower than 101.3 kPa, for each decrease of 1.33 kPa, add 0.3 °C to the observed temperature; when higher than 101.3 kPa, for each increase of 1.33 kPa, subtract 0.3 °C from the observed temperature.
  • 7.1.2 When butane or propane-butane mixture type liquefied petroleum gas is vaporized: when the atmospheric pressure at the test location is lower than 101.3 kPa, for each decrease of 1.33 kPa, add 0.4 °C to the observed temperature; when higher than 101.3 kPa, for each increase of 1.33 kPa, subtract 0.4 °C from the observed temperature.
• Calculation formula: not provided in the available source (the original text expresses the correction rules in words and does not give a formula).

10. Precision

Judge the reliability of the test results according to the following provisions (95% confidence level):

• 8.1 Repeatability: the difference between two results obtained by the same operator from repeated determinations shall not exceed 0.6 °C.
• 8.2 Reproducibility: the difference between two results each submitted by different laboratories shall not exceed 0.9 °C for butane and propane-butane mixed type liquefied petroleum gas; and shall not exceed 1.3 °C for propane type liquefied petroleum gas.

11. Report

Take the arithmetic mean of the two results from repeated determinations as the test result (Chapter 9).

12. Referenced Documents

• GB 510 Petroleum products—Determination of freezing point
• GB 6533 Determination of water and sediment in crude oil (centrifuge method)
• SY 2084 Liquefied petroleum gas sampling method
• Reference: ASTM D1837-86 "Standard Test Method for Volatility of Liquefied Petroleum Gases"

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 Q&A