SH/T 0184-1992 Determination of storage stability of diesel fuel (glacial acetic acid-formaldehyde method)

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Card type: Test method

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

• Method number: SH/T 0184-92
• Full title: Determination of storage stability of diesel fuel (glacial acetic acid-formaldehyde method)
• English name: not provided in the available source
• Replacement relationship: replaces ZB E31 015-89
• Year confirmation: confirmed in (2001)
• Approval/implementation: approved by China Petrochemical Corporation 1992-05-20, implemented on 1992-05-20

2. Scope of application and non-applicability

• Scope of application: applicable to diesel fuel without additives.
• Purpose: to predict oil stability by reacting glacial acetic acid and formaldehyde with the sample and determining the residue.
• Non-applicability: not provided in the available source.

3. Method principle

Add a certain amount of glacial acetic acid and formaldehyde to a certain amount of sample, mix thoroughly, discard the reacted sample, dry and weigh the remaining residue that is insoluble in oil and petroleum ether, and express it as a mass percentage [%(m/m)].

4. Reagents and materials (purity / preparation)

• 4.1 Glacial acetic acid: analytical grade. Corrosive, do not touch the skin. Note: the ambient temperature during use should be higher than 15℃ (the source source-text extraction is "[unreadable value]℃", requires confirmation against the source standard (source-text extraction)), to prevent glacial acetic acid from crystallizing and affecting the operation.
• 4.2 Formaldehyde solution: analytical grade (content not less than 36%), has an irritating odor, polymerizes and becomes cloudy when cold (with precipitation phenomenon), take the upper transparent solution when using.
• 4.3 Petroleum ether: analytical grade, 60～90℃.
• 4.4 Benzene: analytical grade.
• 4.5 95% Ethanol: analytical grade. Prepare benzene and 95% ethanol into a benzene-ethanol solution with a volume ratio of 1:1.

5. Instruments and equipment

• 3.1 Electric shaker (Kang's): shaking frequency about 275 times per minute.
• 3.2 Centrifuge: rotation speed 0～4000 r/min (the source source-text extraction is ".[unreadable characters])00r/nun", requires confirmation against the source standard (source-text extraction)), using a low speed of about 2000 r/min is sufficient, which corresponds to a relative centrifugal force of about 5000.
• 3.3 Analytical balance: sensitivity 0.1 mg.
• 3.4 Electric thermostatic drying oven: temperature control 140℃±2℃.
• 3.5 Desiccator.
• 3.6 Test tube: diameter 16～18 mm, length 95～100 mm, with ground-glass stopper.
• 3.7 Pipette: 1, 5 mL.
• 3.8 Pipette.
• 3.9 Wash bottle.
• 3.10 Filter paper.

6. Recommended operating conditions

• Drying oven temperature: 140℃±2℃.
• Shaker shaking frequency: about 275 times/min.
• Shaking angle: about 45° angle (the source source-text extraction is "450 angle", requires confirmation against the source standard (source-text extraction)).
• Centrifuge speed: low speed about 2000 r/min (relative centrifugal force about 5000).
• Ambient temperature: when using glacial acetic acid, it should be higher than 15℃ (the source source-text extraction is "[unreadable value]℃", requires confirmation against the source standard (source-text extraction)).

7. Sampling and sample preparation

• After sampling, the test should generally be carried out immediately; if it cannot be carried out immediately, the sample should be stored at low temperature and protected from light.
• The sample for testing needs to be filtered; take 5 mL of the filtered sample.

8. Analysis steps

• 6.1 Place a clean, dry test tube (the test tube after testing is cleaned with 1:1 benzene-ethanol solution) in an oven at 140℃±2℃ for constant temperature for 1 h, then place in a desiccator to cool for 30 min and weigh, until the difference between two weighings does not exceed 0.0004 g (the source source-text extraction is ". .00048", requires confirmation against the source standard (source-text extraction)).
• 6.2 Take 5 mL of the filtered sample into a test tube of constant weight, and weigh its mass. Then add 1 mL formaldehyde solution and 5 mL glacial acetic acid.
• 6.3 After covering the above test tube with a ground-glass stopper, place it on a shaker (at about 45° angle) and shake for 15 min (the source source-text extraction is "[unreadable characters]n", requires confirmation against the source standard (source-text extraction)), then remove the test tube from the shaker and place it in a centrifuge for centrifugal separation for 5 min (the source source-text extraction is "5cnin", requires confirmation against the source standard (source-text extraction)), so that the oil and solvent separate into two phases.
• 6.4 Carefully remove the oil phase in the test tube with a pipette, then carefully rinse the ground-glass stopper, the test tube wall and the lower solvent phase with petroleum ether, shake well, let stand briefly, then discard the upper petroleum ether. Repeat this operation no less than four times until the oil traces in the test tube and solvent phase are washed clean.
• 6.5 Place the cleaned test tube with the solvent phase in an oven at 140℃±2℃ and dry for 5 h to evaporate the solvent (because the solvent has an irritating odor, the oven should be placed in a well-ventilated fume hood, and extra care should be taken during operation for safety), then place in a desiccator, cool for 30 min and weigh. Until the difference between two weighings does not exceed 0.0004 g (the source source-text extraction is "0.00048", requires confirmation against the source standard (source-text extraction)), the increase in mass of the test tube obtained by weighing is the amount of residue generated.

9. Qualitative and quantitative determination and calculation formula

The amount of residue generated after the sample reaction X [%(m/m)] is calculated according to the following formula:

X = (m₂ − m₁) / m × 100

Where:

• m₁ — mass of the test tube, g;
• m₂ — mass of the test tube plus residue, g;
• m — mass of 5 mL sample, g.

(Note: the formula part in the source source-text extraction is severely incomplete, only noise such as "o X [unreadable characters] - - X" remains; the above formula is organized according to the textual description and symbol definitions, requires confirmation against the source standard (source-text extraction).)

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 of repeated determinations by the same operator shall not be greater than the following values.

8.2 Reproducibility: the difference between two results submitted by different laboratories shall not be greater than the following values.

(Note: in the source, the "Residue, %(m/m)" column source-text extraction is "[unreadable character]", "X0.20", etc., organized according to context as ≤0.20, requires confirmation against the source standard (source-text extraction).)

11. Report

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

12. Referenced documents

not provided in the available source.

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