SH/T 0308-1992 (2004) Determination of air release value of lubricating oils

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

• Method number: SH/T 0308-92
• Full name: Determination of air release value of lubricating oils
• English name: not provided in the available source
• Replacement relationship: replaces SY 2693-85
• Year confirmation: approved in 1992-05-20, implemented in 1992-05-20; (confirmed in 2004)
• Reference adoption: ASTM D3427-75 "Determination of bubble separation time of petroleum oils"

2. Scope of application and non-applicability

• Scope of application: This standard specifies a method for determining the ability of lubricating oils to separate entrained air; it is applicable to petroleum products such as turbine oils and hydraulic oils.
• Non-applicability: not provided in the available source.

3. Method principle

Heat the sample to 25, 50 or 75 ℃; by blowing excess compressed air into the sample, the sample is vigorously agitated, and the air forms small bubbles in the sample, namely entrained air. After stopping the air, record the time for the volume of entrained air in the sample to decrease to 0.2%.

4. Reagents and materials (purity / preparation)

• 4.2.1 Compressed air: filtered air from which water and oil have been removed, or bottled compressed air (the source wording is unclear; its interpretation as water and oil remains unverified).
• 4.2.2 Chromic acid cleaning solution: 50 g potassium dichromate dissolved in 1 L sulfuric acid, stored in a ground-glass-stoppered glass bottle for cleaning use.
• Other reagents: not provided in the available source.

5. Apparatus and equipment

• 4.1 Apparatus composition: compressed air cylinder, pressure reducing valve, air filter, air heating furnace, pressure gauge, thermometer, heat-resistant jacketed glass test tube, circulating water bath (see Figure 1).
• 4.1.1 Heat-resistant jacketed glass test tube (as shown in Figure 2): a jacketed sample tube through which circulating water can pass, with a ground-glass joint at the tube mouth that fits tightly and can withstand a pressure of 19.6 kPa (0.2 kgf/cm²); the tube is equipped with an air inlet capillary, an oil baffle, and an air outlet tube.
• 4.1.2 Air release value tester: composed of a pressure gauge [0–98 kPa (0–1 kgf/cm²)], an air heating furnace (600 W), and a thermometer (0~100 ℃, scale division 1 ℃).
• 4.1.3 Circulating water bath: capable of maintaining the test tube at a constant temperature of 25, 50 or 75 ℃±1 ℃.
• 4.1.4 Small hydrometers: one set of four, ranges 0.8300–0.8400, 0.8400–0.8500, 0.8500–0.8600, 0.8600–0.8700 g/cm³, scale division 0.0005 g/cm³.
• 4.1.5 Stopwatch.
• 4.1.6 Oven: capable of controlling temperature to 100 ℃.
• Figure 2 dimension annotations (original numbers, units as in the original): air inlet φ10±0.4, 1±0.3, φ40±0.8, 1.6±0.3, 80-5, water outlet 35±3, 1042--, hole φ7±1, baffle φ70±15, 2.2 0.3, 1.8±0.3, A 40±3, 2, φ50±1, 380±20, 250±10, φ10±0.4, 1.5±0.3, water inlet 35±3, -10+2, outer φ8±0.3, inner 2±0.3 (some values are suspected to be source-text extraction noise, requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Test temperature: 25, 50 or 75 ℃.
• Circulating water bath constant temperature: 25, 50 or 75 ℃±1 ℃.
• Aeration pressure: gauge pressure 19.6 kPa (0.2 kgf/cm²).
• Air temperature: controlled within the range of 5 ℃ of the test temperature.
• Aeration time: (420±1)s((7±?)min, the original text "(420 1)s((7min)" is suspected to be 420 s±1 s, namely 7 min, requires confirmation against the source standard (source-text extraction)).
• Sample amount: 180 mL.
• Circulating constant-temperature time: generally 30 min.

7. Sampling and sample preparation

• Sampling: not provided in the available source.
• Sample preparation: not provided in the available source.
• Pre-test treatment: assemble the heat-resistant jacketed glass test tube that has been cleaned with chromic acid cleaning solution and dried according to Figure 1; pour 180 mL of sample into the test tube, and place the small hydrometer into it.

8. Analysis procedure

• 5.1 Assemble the heat-resistant jacketed glass test tube that has been cleaned with chromic acid cleaning solution and dried according to Figure 1.
• 5.2 Pour 180 mL of sample into the heat-resistant jacketed glass test tube, and place the small hydrometer into it.
• 5.3 Turn on the circulating water bath and let the sample reach the test temperature; generally circulate for 30 min.
• 5.4 Read from the small hydrometer to 0.001 g/cm³; use tweezers to move the small hydrometer up and down, let it stand, and then read once more; the two readings should be consistent. If the two readings do not repeat, read again after 5 min until they repeat. Record this density value, which is the initial density d₀.
  • Note: A density balance of the same precision or higher precision (scale division 0.0001 g/cm³) may also be used. When using a density balance, place the sinker in a covered glass cylinder and put it into the circulating bath so that the sinker reaches the test temperature. After the sinker reaches the test temperature, carefully immerse it in the sample without air bubbles adhering to it. Attach the sinker to the beam of the density balance with a platinum wire so that the distance from the bottom of the sinker to the bottom of the jacketed test tube is 10 mm±2 mm.
• 5.5 Remove the small hydrometer from the test tube and place it in the oven, maintaining it at the test temperature. Place the air inlet tube (as shown in Figure 2) into the test tube, connect the air source, and after 5 min introduce compressed air, bringing the pressure to a gauge pressure of 19.6 kPa (0.2 kgf/cm²) at the test temperature; maintain the pressure and temperature, adjusting if necessary. While aerating, turn on the air heater at the same time so that the air temperature is controlled within the range of 5 ℃ of the test temperature.
• 5.6 (420±1)s((7 min) then stop introducing air and immediately start the stopwatch. Quickly remove the air inlet tube from the test tube, take the small hydrometer out of the oven, and put it back into the test tube.
• 5.7 When the hydrometer value changes until the air volume decreases to 0.2%, that is, d=d₀-0.0017, record the time from stopping the air to this point. If bubble separation occurs within 15 min, record the time to the nearest 0.1 min; if greater than 15~30 min, record to the nearest 1 min; if after stopping the air for 30 min the density value has still not reached the d value, stop the test.
  • Note: When reading the small hydrometer, if bubbles adhere to the stem, gently move the hydrometer to avoid the bubbles and then read.

9. Qualitative and quantitative determination and calculation formula

• Definition of air release value: under the conditions specified in this standard, the time required for the volume of entrained air in the sample to decrease to 0.2%; this time is the bubble separation time, expressed in minutes (min).
• Judgment relationship: d = d₀ - 0.0017 (corresponding to the air volume decreasing to 0.2%).
• Calculation formula: not provided in the available source (report directly as time).

10. Precision

Precision table (unit: min)

• 7.1 Repeatability: the difference between two results of repeated determinations shall not exceed the repeatability value in the above table.
• 7.2 Reproducibility: the difference between two results determined by two laboratories shall not exceed the reproducibility value in the above table.

11. Report

Report the bubble separation time of the sample at a certain temperature, expressed in minutes, which is the air release value at that temperature.

12. Referenced documents

• ASTM D3427-75 "Determination of bubble separation time of petroleum oils" (reference adoption)
• Other 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 Q&A