SH/T 0024-1990 Determination of Precipitation 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

• Standard number: SH/T 0024-90
• Chinese name: Determination of Precipitation Value of Lubricating Oils
• English name: not provided in the available source
• Replacement relationship: not provided in the available source (the source text marks "(2([garbled year] confirmed)", suspected to be year confirmation information, requires confirmation against the source standard (source-text extraction))
• Reference adoption: ASTM D 91-87 "Determination of Precipitation Value of Lubricating Oils" (see additional notes)
• Approval/implementation: approved by China Petrochemical Corporation 1991-03-27, implemented on 1992-04-01

2. Scope of application and non-applicability

• Scope of application: This standard specifies the determination method for precipitation value in lubricating oils; applicable to lubricating oils.
• Non-applicability: not provided in the available source.

3. Method principle

At room temperature, take 10mL test sample, dilute with precipitation petroleum ether to 100mL. After mixing uniformly, under the action of a relative centrifugal force of 600～700, rotate the centrifuge tube for 10min. The milliliters of precipitate formed at the bottom of the centrifuge tube is the precipitation value of the test sample.

4. Reagents and materials (purity / preparation)

• Precipitation petroleum ether: see Appendix A.
• Appendix A (supplementary document) quality requirements for precipitation petroleum ether:

• Safety note (Appendix A): Precipitation petroleum ether is a flammable product; open flame heat sources are strictly prohibited during testing, and the entire process should be carried out under good ventilation conditions; storage containers should be sealed and stored in a dark, ventilated place; do not inhale its vapor or allow contact with eyes and skin during use.

5. Instruments and equipment

• 4.1 Centrifuge tube: conical, dimensions as shown in the original figure, made of fully annealed heat-resistant glass; the graduations should be clear, and the shape of the tube mouth should be suitable for tightly stoppering with a cork; the minimum division between different graduation marks and the allowable graduation error are shown in Table 1; other centrifuge tubes meeting the requirements of this standard may also be used.
• 4.2 Centrifuge: should be capable of providing a relative centrifugal force of 600～700 at the tip of the tube, and capable of rotating two or more centrifuge tubes containing test samples at a certain speed; during operation, the rotating head, trunnion cups, trunnion rings, and rubber cushions should be tightened to withstand the maximum centrifugal force that the power source can deliver; during rotation, the trunnion cups and rubber cushions should firmly support the centrifuge tubes; a metal cover or metal box should be used to enclose it, and the metal cover (or box) should have sufficient strength to prevent rupture and danger.
• Centrifuge rotating head speed n (r/min) calculation formula: n = 1337 × √(r_cf / d) (source text source-text extraction is ".=1337[garbled formula symbols]", requires confirmation against the source standard (source-text extraction)); where r_cf is the relative centrifugal force, which should be taken as 600～700; d is the rotation diameter, i.e., the distance between the ends of two opposite centrifuge tubes during rotation, unit mm (source text "yf fno", requires confirmation against the source standard (source-text extraction)).
• The rotation speeds of centrifuges with various rotation diameters are shown in Table 2.
• 4.3 Platform scale: sensitivity 0.1g.
• 4.4 Water bath: temperature control accuracy ±0.5℃.

Table 1 Allowable graduation error of centrifuge tubes (mL):

Table 2 Rotation speeds of centrifuges with different rotation diameters (the original data source-text extraction has significant noise; the following is the identifiable content, requires confirmation against the source standard (source-text extraction)):

(In the original Table 2, "32 5 350 370", "41[unreadable character] [unreadable character]50 483 508 533 [unreadable character]59", etc. are source-text extraction noise and cannot be reliably restored, requires confirmation against the source standard (source-text extraction))

6. Recommended operating conditions

• Water bath temperature after dilution: 32～35℃
• Water bath placement time: 5min
• Centrifugation relative centrifugal force: 600～700
• Centrifugation time: 10min
• Number of times to invert the centrifuge tube: at least 20 times each time (two rounds in total)
• Reading precision: read to 0.1mL, estimate to 0.05mL

7. Sampling and test sample preparation

• 6.1 Sampling: carry out according to GB/T 4756.
• 6.2 At room temperature, inject 10mL test sample into each of two clean, dry centrifuge tubes, dilute the test sample in the centrifuge tubes with precipitation petroleum ether to the 100mL mark, and stopper tightly (rubber stoppers must not be used). Then invert back and forth at least 20 times, and each time when inverting, allow the liquid at the conical tip of the centrifuge tube to flow out completely. Place the above centrifuge tubes in a water bath at 32～35℃, leave for 5min, then immediately open the stoppers to release pressure. Stopper the centrifuge tubes again, and invert the centrifuge tubes back and forth at least 20 times as described above.

8. Analysis procedure

• 6.3 Place the two balanced centrifuge tubes in opposite positions of the centrifuge. Then rotate the centrifuge tubes for 10min at a speed sufficient to generate a relative centrifugal force of 600～700, stop and remove, and read the precipitate volume in the centrifuge tubes. Repeat the above rotation operation until three consecutive readings remain constant.

9. Qualitative and quantitative determination and calculation formula

• 7 Calculation: read the volume of solid precipitate at the bottom of each centrifuge tube, read to 0.1mL, estimate to 0.05mL. If the difference between the readings of the two centrifuge tubes is not greater than 0.1mL, report the average of these two readings as the precipitation value; if the difference between the two readings is greater than 0.1mL, then carry out two more determinations and take the average of the four determination results as the precipitation value.
• Centrifuge speed calculation formula: n = 1337 × √(r_cf / d), where r_cf is taken as 600～700, and d is the rotation diameter (mm).

10. Precision

When the precipitation value is in the range of 0.00～1.20mL, use the following provisions to judge the reliability of the test results (95% confidence level).

• 8.1 Repeatability: the difference between two results obtained by the same operator in repeated determinations should not be greater than 10% of the average value.
  • Note: When the precipitation value is below 0.5mL, its repeatability is 0.05mL (source text ".5.L", requires confirmation against the source standard (source-text extraction)).
• 8.2 Reproducibility: the difference between two results respectively proposed by different laboratories should not be greater than 30% of the average value.
  • Note: When the precipitation value is below 0.20mL, its reproducibility is 0.05mL.

11. Report

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

12. Referenced documents

• GB/T 262 Determination of Aniline Point of Petroleum Products
• GB/T 1884 Laboratory Determination of Density of Crude Petroleum and Liquid Petroleum Products (Hydrometer Method)
• GB/T 1885 Petroleum Measurement Tables
• GB/T 4756 Manual Sampling of Petroleum Liquids
• GB/T 6536 Determination of Distillation of Petroleum Products
• ASTM D 91-87 (reference adoption, see additional notes)

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