GB/T 12579-1990 Determination of foaming characteristics of lubricating oils

Summary page. This page is a compiled excerpt/summary of the standard — it is not the full standard text and does not replace it. Verify every value against the official standard and the product certificate before use.

GB/T 12579-1990 specifies the determination of the foaming characteristics of lubricating oils; this page is a historical study note on the superseded 1990 edition, covering its three test procedures, apparatus thresholds, precision and reporting.

Evidence note: the 1990 edition was wholly replaced by the 2002 edition; this page is original historical study material prepared from the 8-page original of the same edition and is not the full text of the standard. Technical review is pending; the curves, manufacturing drawings and controlled operating steps have not been reconstructed, and the page is not a basis for automatic chart look-up or for product applicability.

Version identity and historical position: Original PDF 1/8; two official records of replacement by the 2002 edition. This page addresses GB/T 12579-1990, "Determination of foaming characteristics of lubricating oils"; the original first page prints GB/T 12579-90, approved 1990-12-14 and implemented 1991-10-01. The official 2002 record lists it as wholly replacing the 1990 edition, implemented 2002-12-01. This page serves only as historical study of that old edition and does not replace the 2002 edition or determine current applicability. The original additional note states that the standard was adopted with reference to ASTM D892-74 (84); technical equivalence cannot be inferred from this. When the original edition came into force it superseded SY 2669-77 (confirmed in 1988); this is a historical statement of the original edition.

Scope: Original PDF 1, clauses 1 and 3. Under the specified conditions the foaming tendency and foam stability of lubricating oils are observed. Foam volume is the result; it cannot be taken as an air-release value, as a value on a product certificate, or as a storage condition. The method simulates specified conditions and does not directly prove that an oil is suitable for a given item of equipment in the field.

Principle: Original PDF 1/3/4, clauses 3 and 7. Procedure I consists of two readings at 24 °C, one after air has been passed and one after standing. Procedure II uses a second portion of sample, tested at 93.5 °C. Procedure III uses the sample from Procedure II, collapses the foam, cools it and repeats the test at 24 °C. The sample origin and the temperature sequence of the three procedures must not be mixed.

Apparatus: Original PDF 1/2/3, clause 4. The test equipment comprises a 1000 mL graduated cylinder with an inlet tube and a sintered crystalline alumina diffusion head. The diffusion head is 25.4 mm in diameter with a maximum pore diameter not greater than 80 μm; at 2.45 kPa (250 mm H₂O) the air permeability is 3000–6000 mL/min. These are the checking conditions for the diffusion head, not the 94 ± 5 mL/min of the foam test. The test bath must be transparent and must immerse the cylinder at least to the 900 mL mark, with bath temperatures of 24 ± 0.5 °C and 93.5 ± 0.5 °C. The fully immersed thermometers cover 0–50 °C and 48–102 °C with a minimum division of 0.1 °C; the timer has a division of 1 s or better. The complete manufacturing drawings and all assembly dimensions have not been reconstructed.

Reagents and reference materials: Original PDF 2/3, clauses 4–6. The original edition lists chemically pure toluene, acetone, 30–60 °C petroleum ether, and a solvent naphtha conforming to the originally cited GB 1922. The solvents are flammable and volatile and their vapour is toxic; ventilation and fire precautions must be maintained. This page is not a controlled safety procedure. The clean, dry air passes through a 300 mm drying tower: above the constriction, in order, 20 mm of absorbent cotton, 110 mm of desiccant, 40 mm of indicating silica gel, 30 mm of desiccant and 20 mm of absorbent cotton. Indicating silica gel that shows moisture must be refilled; the name of a desiccant is not a basis for guessing product storage.

Key conditions: Original PDF 3, clause 6 (cleaning and equipment preparation). After each test, additive residues from the previous test must be removed, otherwise the result is affected. The cylinder is washed with solvent naphtha, distilled water and acetone and blown dry with air; the diffusion head is successively sucked and pressure-flushed in the listed solvents, at least five times in each, and then blown dry. The whole system must be sealed and free from leaks, and both baths must reach the specified temperature beforehand.

Procedure I: sampling and key readings: Original PDF 3, clause 7.1. A 200 mL sample is first brought to 49 ± 3 °C without mechanical shaking or stirring, then cooled to 24 ± 3 °C. It is poured into the cylinder to the 190 mL mark with the bath at 24 ± 0.5 °C; when the sample has reached bath temperature, the diffusion head, not yet connected to the air supply, is inserted and soaked for 5 min. Timing starts at the first bubble; air is passed at 94 ± 5 mL/min for 5 min ± 3 s; the air supply is cut and the foam volume is read immediately, the total gas volume being 470 ± 25 mL. After standing for 10 min ± 10 s the foam is read again, to 5 mL. Time, flow rate and total volume are each checked; none of them may substitute for the other thresholds.

Procedure II and Procedure III linkage: Original PDF 3/4, clauses 7.2/7.3. A second portion of sample is filled to the 180 mL mark with the bath at 93.5 ± 0.5 °C; when the sample reaches 93 ± 1 °C the diffusion head is inserted and timing and readings follow Procedure I. The test is started as soon as the specified temperature is reached, and the sample is kept in the 93.5 °C bath for no more than 3 h. The residual foam of the Procedure II sample is collapsed, the sample is cooled at room temperature to below 43.5 °C and placed in the 24 ± 0.5 °C bath, and once it has reached bath temperature it is tested as in Procedure I. The original steps 7.1/7.3 are to be completed within 3 h of completing the preceding step.

Optional step A and the limits on its use: Original PDF 4, clause 7.4. The original edition describes aggregation of anti-foam agent particles that may occur after storage for two weeks or longer, and optional step A may be considered for the corresponding stored sample to redisperse them; it is not suitable for quality control of freshly blended oils, and vigorous stirring can produce a falsely good result. A 500 mL sample at 18–32 °C is placed in a 1 L high-speed stirring vessel, covered and stirred at maximum speed for 1 min; it is left until the entrained bubbles have dispersed and the oil temperature is 24 ± 3 °C, and tested by Procedure I within 3 h of stirring. If a viscous sample requires a longer de-aeration time, this is recorded and noted; the optional step or a time deviation may not be left unstated.

Simplified procedure and report designation: Original PDF 4, clause 8. The routine simplified procedure does not measure the 5 min total air volume and dispenses with the gas-volume measuring device and the sealed outlet connection; the flow meter must still be accurately calibrated and the flow rate controlled. Results obtained by this procedure must be reported explicitly as GB/T 12579 (simplified method) and must not be passed off as a complete volume check.

Precision graphs and applicability limits: Original PDF 4/5/6, clause 9, figures 3/4. The original edition gives repeatability/reproducibility at the 95 % confidence level, the specified values being read from figures 3/4, which distinguish Procedure II and Procedures I/III. The dense curves have not been digitised, and no linear formula or published chart calculator may be guessed from the plotted lines. No precision is specified for optional step A; the original note states that in most laboratories method A gave no foam and precision was not calculated. Method precision is not the uncertainty of a batch certificate and cannot be applied to method A.

Calculation and results: Original PDF 4/5, clause 10. For each procedure the tendency volume at the end of the 5 min aeration and the stability volume at the end of the 10 min standing are reported separately, in mL; results are reported separately for the sample as received and for optional step A after stirring. In original 10.2, if the foam does not completely cover the surface, is fragmentary, or shows eye-shaped clear liquid, the result is judged to be no foam and reported as 0 mL; a volume must not be inferred from a single local bubble. Procedure | Temperature | Tendency reading | Stability reading I | 24 °C | end of aeration, mL | end of standing, mL II | 93.5 °C | end of aeration, mL | end of standing, mL III | 24 °C | end of aeration, mL | end of standing, mL

Annex A: pore diameter and permeability kept separate: Original PDF 7/8, reference annex A. Annex A was listed as a reference annex in the original. For the pore-size check the cleaned diffusion head tip is immersed 100 mm for at least 2 min and pressurised at about 490 Pa/min (50 mm H₂O/min); the water-column pressure difference P is read at the first bubble and when bubbling is continuous. D = 29225/(P − 100), with D in μm and P in mm H₂O. Pa values must not be substituted directly for P, and no automatic calculation is offered on this page. Permeability is measured with a clean, dry diffusion head and a wet test meter at 2.45 kPa (250 mm H₂O) in mL/min, and the observation may be extended to obtain a per-minute average. The apparatus drawings A1/A2 and all controlled operating steps have not been reconstructed.

Sources, unverified items and limits of use: Eight physical pages of the original of the same edition and public edition records. All eight pages of the original were reviewed visually, with the timing/temperature of PDF 3 and the formula of PDF 7 cross-checked in particular. The original PDF and OCR are read-only; scans are not published. The precision curves of figures 3/4, the complete component manufacturing drawings, controlled solvent safety and instrument calibration have not been reconstructed; technical review is pending. Text describing old standards and adoptions is presented only as a fact of that edition and implies nothing about current regulation, standard equivalence, product applicability, stock, price or certification. The historical edition is kept separate from the existing 2002 entry; independent technical acceptance and the effect of GEO citation are listed separately.

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