GB/T 4929-1985 Determination of dropping point of lubricating grease

GB/T 4929-1985 Determination of dropping point of lubricating grease GB/T4929-1985 Standard download decompression password: www.bzxz.net

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Lubricating grease-Determination of dropping point
This method is applicable to the determination of the dropping point of lubricating grease. 1 Method Overview
UDC 621.892
GB/T 4929-85
(Confirmed in 1991)
This method is to put the lubricating grease into the grease cup of the dropping point meter, and under the specified standard conditions, the temperature at which the lubricating grease reaches a certain fluidity during the test.
2 Instrument
2.1 Grease cup: chrome-plated brass cup. The dimensions are shown in Figure 1. $10.71
Wall chain angle 4
Figure 1 Fat cup
National Bureau of Standards 1985-02-06 Issued
1985~10-01 Implementation
GB/T4929-85
Inner Φ 11.1～12.7
Three equidistant grooves supporting the fat cup
Figure 2 Assembled instrument
1-Thermometer, 2-Ventilation notch on the cork, 3-Cork guide ring, total gap between the ring and the test tube: 1.5mm, 4-Test tube, 5-Fat cup 2.2 Test tube: Heat-resistant borosilicate glass test tube with edge, with three grooves on the circumference for supporting the fat cup, its position and size are shown in Figure 2.
2.3 Thermometer: Dip, meet the specification requirements shown in Appendix A (Supplement). 2.4 Accessories:
2.4.1 Oil bath: consisting of a 600 ml beaker and suitable oil. 2.4.2 Ring stand and ring: used to support the oil bath. 2.4.3 Thermometer clamp.
2.4.4 Cork: as shown in Figure 2.
2.4.5 Polished metal rod: 1.2 to 1.6 mm in diameter and 150 mm in length. 2.4.6 Heater: preferably heated by an immersion resistance heater regulated by a control voltage. 2.4.7 Stirrer.
3 Operating procedures
3.1 To assemble the test apparatus, place two corks on the thermometers as shown in Figure 2, adjusting the position of the upper cork so that the top of the thermometer bulb is about 3 mm from the bottom of the grease cup. Hang the second thermometer in the oil bath so that its bulb is at approximately the same level as the bulb of the thermometer in the test tube.
Note: The position of the top of the thermometer bulb in the test tube is not critical, as long as it does not block the small hole of the grease cup; since the inner surface of the grease cup is coated with a grease film, the thermometer bulb cannot contact the sample.
GB/T4929—85
3.2 Remove the grease cup and press the grease cup into the sample until the cup is filled with the sample. Be as careful as possible to avoid working the sample. Remove the excess sample with a scraper. Hold the grease cup in a vertical position at the bottom hole, gently press the cup, and pass the polished metal rod downward until the rod extends about 25 mm. Press the rod against the grease cup in a way that it contacts the upper and lower circumferences of the cup. Maintaining this contact, use the index finger to rotate the grease cup on the rod so that it moves downward in a spiral. This removes the conical sample attached to the rod. When the grease cup finally slides off the end of the rod, a smooth grease film of repeatable thickness should be left on the inside of the grease cup.
3.3 Place the grease cup and thermometer in the test tube and hang the test tube in an oil bath. Keep the oil level no more than 6 mm from the edge of the test tube. The cork holding the thermometer in the test tube should be appropriately selected so that the 76 mm immersion mark on the thermometer is consistent with the lower edge of the cork. Immerse the assembly to this point.
3.4 ​​Stir the oil bath and raise the temperature at a rate of 4 to 7 °C/min until the oil bath temperature reaches a temperature about 17 °C below the expected dropping point. Then, reduce the heating rate so that the difference between the temperature in the test tube and the oil bath temperature is within 2 °C or less before the oil bath temperature rises another 2.5 °C. Continue heating, heating the oil bath at a rate of 1 to 1.5 °C/min, so that the difference between the temperature in the test tube and the temperature in the oil bath is maintained between 1 and 2 °C.
As the temperature continues to rise, the sample gradually emerges from the hole in the grease cup. When the first drop of fluid drips from the hole in the grease cup, immediately record the temperature on the two thermometers.
Note: ① Some greases, such as some aluminum-based greases, always drip out in a line when melted. It may break or remain until it drips to the bottom of the test tube. In the latter case, record the temperature of the fluid when it reaches the bottom of the test tube. ② The dropping point of some greases, especially those containing aluminum soap, decreases with aging. This drop point change is much larger than the allowable error of the results obtained in different laboratories. Therefore, the comparison test between laboratories must be completed within six days. 3.5 If two samples have approximately the same dropping point, they can be measured simultaneously in the oil bath on Monday. 4 Precision
The following provisions are used to judge the reliability of the results (95% confidence rate). 4.1 Repeatability: The difference between the two results of repeated measurements of the same sample by the same operator on the same instrument should not exceed? ℃. 4.2 Reproducibility: The difference between the results of the same sample measured by different operators in different laboratories should not exceed 13℃. 5 Report
The average of the temperature readings of the oil bath thermometer and the thermometer in the test tube is taken as the dropping point of the sample. 465
Additional remarks:
Immersion depth
Graduation value
Long line scale
Large grid scale
Scale error shall not exceed
Total length
Length of mercury ball
Ball diameter
Distance from the bottom of the ball to the 0℃ scale
Distance from the bottom of the ball to the 300℃ scale
This standard is proposed by China Petrochemical Corporation. This standard is under the jurisdiction of the Petrochemical Research Institute. GB/T 4929—85
Appendix A
Thermometer specifications
(supplement)
This standard was drafted by the Petrochemical Research Institute. The main drafter of this standard is Li Wenhui.
5～300℃
390±5mm
6.5±0.5mm
10~15mm
5.5±0.5mm
100～110mm
329~358mm
This standard is equivalent to the draft international standard ISO/DP 2176-1979 "Determination of dropping point of lubricating grease". 466
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