SH/T 0237-1992 Determination of Storage Stability of Gasoline

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Card type: Test method

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

• Standard number: SH/T 0237-92 (confirmed in 2004)
• Chinese name: Determination of Storage Stability of Gasoline
• English name: not provided in the available source
• Replacement relationship: replaces SY 2124-82
• First issued: 1977
• Approval/implementation: approved by China Petrochemical Corporation in 1992-05-20, implemented in 1992-05-20

2. Scope of application and non-applicability

• This standard specifies the method for determining the storage stability of a sample.
• This standard applies to gasoline.
• Not applicable: not provided in the available source.

3. Method principle

A certain volume of sample is stored at 93℃ for 16h, and its oxygen absorption and total gum formed (the sum of actual gum and sediment) are determined, with the storage stability expressed by the instability index (BZ16) value. The smaller the BZ16 value, the better the storage safety of the sample. It also has a certain correspondence with the results of the 43℃ and room-temperature storage tests.

4. Reagents and materials (purity / preparation)

4.1 Materials

• 4.2.1 Quantitative filter paper: diameter 12.5cm, medium speed.
• 4.2.2 Industrial filter paper.

4.2 Reagents

• 5.1 Benzene: analytical reagent.
• 5.2 Anhydrous ethanol: analytical reagent.
• 5.3 Petroleum ether: 30–60℃ or 60–90℃, analytical reagent, free of aromatic hydrocarbons (tested with sulfuric acid-formaldehyde reagent).
• 5.4 Anhydrous calcium chloride: chemical reagent.
• Benzene-ethanol mixed liquid: 1:1 (volume ratio), used to dissolve sediment (see 6.7).

5. Apparatus and equipment

• 4.1.1 Test bottle: 500mL medical glucose injection bottle, with rubber stopper and aluminum cap for sealing, actual total volume should be 620mL ± 10mL (original text “620mL t 10ad-” requires confirmation against the source standard (source-text extraction)).
• 4.1.2 Test bottle sealing machine.
• 4.1.3 Protective steel bomb: see figure (original figure number requires confirmation against the source standard (source-text extraction)).
• 4.1.4 Workbench for tightening the steel bomb.
• 4.1.5 Glycerol bath: when one steel bomb is loaded, the glycerol volume should be five to six times the steel bomb volume; if more steel bombs are loaded, the glycerol volume must not be less than four times the total steel bomb volume. The glycerol bath is equipped with an automatic stirrer, and the temperature should be automatically controlled at 93℃ ± 0.5℃. Inside the bath, at a height of 2mm from the electric heating element, a sieve plate is installed to support the steel bomb, so as to avoid direct contact with the electric heating element and thereby causing local overheating.
• 4.1.6 Cold water bath: for cooling the steel bomb.
• 4.1.7 Gas chromatograph: with thermal conductivity detector.
• 4.1.8 72 type spectrophotometer.
• 4.1.9 Actual gum tester: instrument conforming to the provisions of GB/T 509.
• 4.1.10 Conical flask: 100mL.
• 4.1.11 Glass funnel: diameter 60mm.
• 4.1.12 Graduated cylinder: 250mL.
• 4.1.13 Wash bottle.
• Appendix A: 13X molecular sieve column; 105 catalyst short column (length 100mm, inner diameter 4mm, original text “inner diameter 4,” requires confirmation against the source standard (source-text extraction)); microsyringe.

6. Recommended operating conditions

6.1 Storage conditions

• Storage temperature: 93℃ ± 0.5℃
• Storage time: 16h
• Store two parallel samples per storage.

6.2 Appendix A Gas chromatography operating conditions

• Column length: 1m
• Column temperature: 50℃ (original text “5090” requires confirmation against the source standard (source-text extraction))
• Stationary phase: 40–60 mesh 13X molecular sieve (activated at 550℃ for 3h before packing the column)
• Bridge current: 180mA (original text “180n lA” requires confirmation against the source standard (source-text extraction))
• Carrier gas: hydrogen
• Flow rate: 40–50mL/min (original text “40[unreadable separator]SOm1/min” requires confirmation against the source standard (source-text extraction))

6.3 Appendix B 43℃ storage test conditions

• Storage container: 500mL brown reagent bottle, each bottle stores 170mL (original text “1705L” requires confirmation against the source standard (source-text extraction))
• Sealing: seal tightly with the plastic stopper and bakelite cap originally used for sealing the reagent bottle, must not leak air
• Storage room temperature: 43℃ ± 2℃ (original text “43`C12'0” requires confirmation against the source standard (source-text extraction))
• Ventilation: every 4 weeks, take out the test bottle once, cool to room temperature, unscrew the cap, leave for about 5–10min to exchange fresh air, then seal again and put back into the storage room to continue storage
• For each analysis, take two sample bottles for parallel analysis
• Rejection criterion: when the loss of the sample during storage is greater than 15% of the original total sample volume, it is considered rejected (original text has an unreadable value followed by % requires confirmation against the source standard (source-text extraction))

7. Sampling and sample preparation

• 6.1 Dehydrate the sample with anhydrous calcium chloride, then filter with industrial filter paper.
• If the sample has been stored for a long time and the sediment contained is considered to exceed 1mg/100mL, the sediment amount should be determined according to clause 6.7.
• 6.3 Accurately measure 130mL of the filtered sample with a graduated cylinder, pour into a clean, dry test bottle. Then, stopper tightly with a rubber stopper, and seal tightly with an aluminum cap using a sealing machine. Store two parallel samples each time.

8. Analysis steps

8.1 Pre-test determination (6.2)

Determine the filtered sample separately:

• Actual gum: according to GB/T 509
• Acidity: according to GB/T 258
• Light transmittance: use 72 type spectrophotometer, reference liquid is distilled water, wavelength 420nm, 1cm cuvette

8.2 Storage test (6.3–6.6)

• 6.3 Measure 130mL of filtered sample into a test bottle, stopper tightly with a rubber stopper, seal tightly with an aluminum cap using a sealing machine. Store two parallel samples each time.
• 6.4 Place the test bottle into the protective steel bomb, and tighten the steel bomb cover on the workbench used for tightening the steel bomb. A rubber gasket should be added inside the steel bomb cover for sealing.
• 6.5 Place the steel bomb into an oil bath or oven already at constant temperature of 93℃ ± 0.5℃, and start timing immediately. At the same time, start stirring the oil bath until the 16h test is terminated. Take out the steel bomb, first wash the glycerol adhering to the surface of the steel bomb with a small amount of tap water into a container, then immediately place the steel bomb into a cold water bath and rapidly cool to room temperature. Open the steel bomb and take out the test bottle. If the test bottle temperature is still higher than room temperature, continue cooling to room temperature.
• 6.6 After the test bottle is cooled, first determine the oxygen content in the reserved space of the test bottle, method see Appendix A.

8.3 Post-test determination (6.7–6.8)

• 6.7 Open the test bottle, filter the sample with quantitative filter paper, and place the filtrate in a clean bottle for later use.
  • First wash the test bottle with petroleum ether until oil-free. Each petroleum ether wash liquid should pass through the above filter paper to collect the sediment washed down. Then, carefully wash the filter paper with petroleum ether until oil-free. Collect all petroleum ether wash liquid in a petroleum ether bottle.
  • Replace the flask under the funnel with a conical flask of constant weight. Dissolve the sediment adhering to the test bottle with benzene-ethanol mixed liquid (1:1 volume ratio) until completely dissolved. Each benzene-ethanol mixed liquid should also flow through the above filter paper to simultaneously dissolve the sediment on the filter paper. Finally, carefully dissolve the sediment on the filter paper with benzene-ethanol mixed liquid until completely dissolved. Place the conical flask in a constant-temperature water bath (about 90℃) to evaporate the solvent, then place in an oven (105℃ ± 3℃) to dry and weigh until the difference between consecutive weighings does not exceed 0.0004g. The weight increase of the conical flask is the sediment amount of the 130mL sample.
• 6.8 Determine the actual gum, acidity, and light transmittance of the filtrate separately (analysis method same as clause 6.2).
  • Note: The acidity and light transmittance of the sample and filtrate are for comparison only.

8.4 Appendix A Determination of oxygen content in the reserved space of the test bottle

• A2.1 Correction of oxygen peak height:
  • Since the chromatographic column cannot separate oxygen and hydrogen, to obtain the oxygen peak height, the hydrogen peak height must first be obtained. Also, since oxygen and hydrogen are consumed during sample storage (original text “nitrogen and hydrogen consumed” requires confirmation against the source standard (source-text extraction)), and the nitrogen and oxygen contents in air are known, the correction factor SA between the nitrogen peak height and the hydrogen peak height in the chromatogram can be determined by removing oxygen from air in advance (original text “SA<” requires confirmation against the source standard (source-text extraction)). In each determination, the nitrogen peak height can be used as a reference to obtain the corresponding hydrogen peak height, thereby obtaining the oxygen peak height.
  • Connect a short column of 105 catalyst (activation conditions according to manufacturer's instructions) of length 100mm and inner diameter 4mm before the 13X molecular sieve column. Under the specified operating conditions, inject an appropriate amount of air so that the nitrogen peak height is close to full scale. Since the oxygen in the air sample is removed by hydrogenation to water under the action of the 105 catalyst, a nitrogen peak and a hydrogen peak can be obtained on the recorder. The relative peak height correction factor SAr of hydrogen to nitrogen is obtained from the peak height ratio of hydrogen peak to nitrogen peak, calculated according to formula (A1):
    • SA = (hA / hN) × 78 (original formula source-text extraction has severe noise, requires confirmation against the source standard (source-text extraction))
    • Where: hA— hydrogen peak height, mm; hN— nitrogen peak height, mm.
  • The hydrogen peak height corresponding to any nitrogen peak height can be obtained from formula (A2):
    • hA = (hN / 78) × SAr (original formula source-text extraction has severe noise, requires confirmation against the source standard (source-text extraction))
  • In actual determination, the corrected oxygen peak height hO (mm) can be obtained by subtracting the hydrogen peak height from the actual height of the oxygen-hydrogen peak, calculated according to formula (A3):
    • hO = h(O-H) − (hN / 78) × SAr (original formula source-text extraction has severe noise, requires confirmation against the source standard (source-text extraction))
    • Where: h(O-H)— oxygen-hydrogen peak height, mm.
  • Because the value of SAr is related to operating conditions, after changing operating conditions or replacing the chromatographic column, SAr should be re-determined.
• A2.2 Oxygen content analysis steps:
  • Use a microsyringe to take an appropriate amount (60–100μL) of the gas phase sample from the reserved space of the test bottle, inject into the chromatographic column, so as to produce a nitrogen peak and oxygen-hydrogen peak close to full scale, repeat once or twice to produce a reproducible spectrum. Then inject an appropriate amount of air so that the nitrogen peak produced is similar in height to the nitrogen peak of the sample, repeat once or twice to produce a reproducible spectrum.

9. Qualitative and quantitative and calculation formulas

9.1 Sediment calculation (formula 1)

The sediment X (mg/100mL) of the sample is calculated according to formula (1):

• X = (m2 − m1) / 130 × 100 (the original formula source-text extraction is severely noisy, requires confirmation against the source standard (source-text extraction))
• Where: m1— mass of the conical flask, mg; m2— total mass of the conical flask and sediment, mg.

9.2 Calculation of instability index BZ16 (formula 2)

The instability index BZ16 of the sample is calculated according to formula (2):

• BZ16 = [(O0 − O16) / O0] × (m16 − m0) (the original formula source-text extraction is severely noisy, requires confirmation against the source standard (source-text extraction))
• Where: O0— oxygen content in the reserved space of the test bottle before the test [usually 21.0%(V/V)], %(V/V); O16— oxygen content in the reserved space of the test bottle after the test, %(V/V); m0— total gum content of the sample before the test, mg/100mL; m16— total gum content of the sample after the test, mg/100mL.
• Note: When O16 %(V/V) is greater than 20.0%(V/V), the term O0 − O16 shall always be taken as 1.0%(V/V) for calculation.

9.3 Appendix A Calculation of oxygen content (formula A4)

The oxygen content O16 [%(V/V)] in the reserved space of the test bottle is calculated according to formula (A4):

• O16 = [0.99 × 100] / [3.72 × (Re / Rs) + 1] (the original formula source-text extraction is severely noisy, requires confirmation against the source standard (source-text extraction))
• Where: Re— ratio of the oxygen peak height to the nitrogen peak height of the air sample; Rs— ratio of the oxygen peak height to the nitrogen peak height of the gas sample in the test bottle; 3.72— nitrogen-to-oxygen ratio in air.
• Note: All oxygen peak heights are values after subtracting the hydrogen peak height.

9.4 Appendix C Prediction of 43℃ storage test results using BZ16 value (formula C1)

For a sample stored under 43℃ for a certain time, the total gum content m43 (mg/100mL) in the test is calculated according to formula (C1):

• m43 = m(BZ16) + m0 + C
• Where: m0— total gum content in the sample before the test, mg/100mL; C— constant, which is 1.2; BZ16— instability index; m— constant, which varies with different storage times under 43℃.
• Corresponding to 43℃ storage for 8 weeks: m = 0.23
• Corresponding to 43℃ storage for 16 weeks: m = 0.78
• Corresponding to 43℃ storage for 32 weeks: m = 9.15
• The m value corresponding to any storage time under 43℃ can be found from Figure C1.
• In addition, the above prediction results can be found using the nomograph (Figure C2).
• Instructions for using Figure C2: After the BZ16 value of a sample has been measured, if one wants to predict the amount by which the total gum in the sample can increase after any storage time under 43℃, find on the BZ16 line of Figure C2 the point corresponding to the BZ16 value of that sample, then find on the line of storage weeks under 43℃ the point corresponding to the storage time; connect these two points with a straight line, which intersects the middle line at a point, and at that point the desired result can be read. Conversely, if one wants to predict the maximum storage time that the sample can be stored when reaching a certain total gum amount, similarly first determine a corresponding point on the BZ16 line of Figure C2, then find on the middle line of that figure the point corresponding to the specified total gum amount; connect the two points with a straight line, extend this line to intersect the line of storage weeks under 43℃ at a corresponding point, and the data marked at that point is the desired result.

10. Precision

Repeatability: The difference between two results of repeated determinations by the same operator and their arithmetic mean shall not exceed the following values.

11. Report

Take the arithmetic mean of two results of repeated determinations as the test result.

12. Normative references

• GB/T 258 Determination of acidity of gasoline, kerosene and diesel fuel
• GB/T 509 Determination of existent gum in engine fuels

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