GB/T 513-1977 Determination of mechanical impurities in lubricating grease (acid decomposition method)

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Card type: Test method

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

• Standard number: GB 513-77 (confirmed in 1988)
• Chinese name: Determination of mechanical impurities in lubricating grease (acid decomposition method)
• English name: Lubricating grease—Determination of mechanical impurities—Acid decomposition method
• Replacement relationship: replaces GB 513-65
• Issued/implemented: issued by the National Bureau of Standards and Metrology 1977-02-04, implemented 1977-07-01

2. Scope of application and non-applicability

• Applicable to the determination of the content of mechanical impurities in lubricating grease that are insoluble in hydrochloric acid, petroleum ether (solvent gasoline or benzene), ethanol-benzene mixed liquid, and distilled water.
• Also applicable to the determination of the content of fillers specially added to lubricating grease that are insoluble in the above reagents.
• Not applicable: not provided in the available source.

3. Method principle

Weigh the sample in a conical flask (or beaker), add 10% hydrochloric acid, add petroleum ether (solvent gasoline or benzene). Attach a reflux condenser to the conical flask and heat on a water bath or electric furnace (or heat the beaker slowly, but it must boil, stir until the soap blocks are completely dissolved, then add solvent) to completely dissolve the sample. Slowly pour the dissolved material into a weighed fritted glass crucible for filtration. Then wash with ethanol-benzene mixed liquid. Finally, wash the precipitate with hot distilled water until it is neutral. Dry to constant weight; this precipitate is the mechanical impurities.

4. Reagents and materials (purity / preparation)

• 3.1 Hydrochloric acid: chemically pure, prepare a 10% hydrochloric acid solution. When preparing, mix 235 mL of hydrochloric acid with 765 mL of distilled water.
• 3.2 95% Ethanol: chemically pure.
• 3.3 Benzene: chemically pure.
• 3.4 Ethanol-benzene mixed liquid: prepared from 95% ethanol (chemically pure) and benzene (chemically pure) in a volume ratio of 1:4.
• 3.5 Petroleum ether: 60–90℃; or solvent gasoline: 80–120℃.
• Others: methyl orange (used to check neutrality, see 4.5); barium sulfate (used for porosity identification of new crucibles, see 4.5 Note ②); chromic acid cleaning solution, 2% hydrochloric acid aqueous solution (used for crucible cleaning, see 4.5 Note ①).

5. Instruments and equipment

• 2.1 Beaker: 250~400 mL.
• 2.2 Conical flask: 250 mL.
• 2.3 Wash bottle.
• 2.4 Fritted glass crucible: pore size 4.5~15 micrometers.
• 2.5 Scraper.
• 2.6 Suction flask.
• 2.7 Water jet pump or vacuum pump.
• 2.8 Reflux condenser.
• 2.9 Water bath or electric furnace with concealed heating wire.
• Note: If a fritted glass crucible is not available, a Gooch crucible may be used instead; for arbitration tests, use a fritted glass crucible.

6. Recommended operating conditions

• Drying temperature: 105~110℃.
• Drying time: at least 1.5 hours; repeated drying time is 30 minutes.
• Cooling time: 30 minutes (in a desiccator).
• Weighing precision: weigh to the nearest 0.0002 g (4.2, 4.5).
• Constant weight criterion: the difference between two consecutive weighings does not exceed 0.0004 g.
• Heating conditions: for the beaker method, heat slowly but do not heat to boiling; for the conical flask method, attach a reflux condenser and heat on a water bath or electric furnace until the sample is completely dissolved.
• Filtration temperature: if filtration of the mixed liquid is difficult, carefully heat the mixture and filter while hot.

7. Sampling and sample preparation

• 4.1 Scrape off the surface of the sample with a scraper, take samples from at least three places not close to the container wall, collect them in a beaker, and mix uniformly. Samples with very low penetration may not be mixed.
• 4.3.1 Weigh 20~25 g of sample in a beaker, weighed to the nearest 0.1 g.
• 4.3.2 Weigh 20~25 g of sample in a conical flask, weighed to the nearest 0.1 g.

8. Analysis procedure

• 4.2 Dry the fritted glass crucible in a constant-temperature oven at 105~110℃ for at least 1.5 hours, then transfer to a desiccator to cool for 30 minutes, and weigh to the nearest 0.0002 g. Repeat drying for 30 minutes, cool for 30 minutes, and weigh until the difference between two consecutive weighings does not exceed 0.0004 g.
• 4.3 Sample decomposition is carried out by one of the following methods:
  • 4.3.1 Weigh 20–25 g of sample in a beaker, weighed to the nearest 0.1 g. Then add 10% hydrochloric acid 50 mL. Heat the beaker slowly, but do not heat to boiling, while stirring until all soap blocks disappear and the upper layer is clear. After cooling to 35–40℃, add petroleum ether (solvent gasoline or benzene) 50 mL, and mix again.
  • 4.3.2 Weigh 20~25 g of sample in a conical flask, weighed to the nearest 0.1 g. Then add 10% hydrochloric acid 50 mL and petroleum ether (solvent gasoline or benzene) 50 mL, attach a reflux condenser to the conical flask, and heat on a water bath or electric furnace until the sample is completely dissolved.
• 4.4 Slowly pour the dissolved material in the conical flask or beaker into a fritted glass crucible for filtration.
  • Note: If filtration of the mixed liquid is difficult, carefully heat the mixture and filter while hot.
• 4.5 Wash the residual precipitate in the conical flask or beaker onto the fritted glass crucible with ethanol-benzene mixed liquid, then wash the fritted glass crucible with the precipitate using hot ethanol-benzene mixed liquid until a drop of the filtrate on filter paper no longer leaves a mineral oil trace after evaporation. Rinse with a small amount of 95% ethanol, and finally wash the precipitate with hot distilled water until neutral (check with methyl orange). Then wash with 95% ethanol 1~2 times.
• After washing, dry the fritted glass crucible with the precipitate in a constant-temperature oven at 105~110℃ for at least 1.5 hours, then cool for 30 minutes, weigh to the nearest 0.0002 g, repeat drying for 30 minutes, cool for 30 minutes, and weigh until the difference between two consecutive weighings does not exceed 0.0004 g.
• Note ①: Before using a new fritted glass crucible, it must first be treated with acid and alkali, then rinsed with distilled water and dried. After use, it should be soaked in chromic acid cleaning solution for 3–4 hours, taken out, boiled in 2% hydrochloric acid aqueous solution for 20–30 minutes, and then washed clean with distilled water. After drying, place in a desiccator for later use.
• Note ②: Before using a new fritted glass crucible, its porosity should first be identified using barium sulfate precipitate. Preparation of barium sulfate suspension: weigh 3~5 g of barium sulfate, suspend in 100 mL of water, and take the upper turbid liquid with precipitate to identify the fritted glass crucible.

9. Qualitative and quantitative determination and calculation formula

The mechanical impurity content of the sample X (%) is calculated according to the following formula:

X = (G₁ − G₂) / G × 100

Where:

• G₁ — weight of the fritted glass crucible with precipitate, g;
• G₂ — weight of the fritted glass crucible without precipitate, g;
• G — sample weight, g.

Note: If a Gooch crucible is used to determine the mechanical impurity content, a blank test correction should be carried out.

(Note: The original formula source-text extraction is "X=G-0i / 100 / G", suspected to be a typesetting error; it has been arranged into the above formula according to the context and symbol explanations, requires confirmation against the source standard (source-text extraction).)

10. Precision

The difference between two results of repeated determination shall not exceed 0.025%.

11. Report

• 7.1 Take the arithmetic mean of two results of repeated determination as the determination result.
• 7.2 When the result determined with a fritted glass crucible is less than 0.025%, it is considered that there are no mechanical impurities.

12. Referenced documents

not provided in the available source (the main text does not list a normative referenced documents list).

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