This method is suitable for determining the dropping point of lubricating grease over a wide temperature range. GB/T 3498-1983 Determination of dropping point of lubricating grease over a wide temperature range GB/T3498-1983 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Lubricating greases -Determination of dropping point (wide temperature range) This method is applicable to the determination of dropping point of lubricating greases in a wide temperature range. 1 Definition
Under the specified test conditions, the temperature at which the grease reaches a certain fluidity is called the dropping point. 2 Instrument
2.1 The dropping point device (as shown in Figure 1) consists of the following parts: 2.1.1 Grease cup: chrome-plated brass cup. Its dimensions are consistent with those shown in Figure 1, No. 1. 2.1.2 Test tube: thin-walled soft glass test tube with edges. Its dimensions are consistent with those shown in Figure 1, No. 2. 2.1.3
Grease cup holder: glass tube as shown in Figure 1, No. 3. 2.1.4
UDC 665.521.5
：543.24
GB/T 3498--83
（Confirmed in 1991）bZxz.net
Thermometer: As shown in Figure 1, 4. Meet the specifications specified in the appendix (see Appendix A). Accessories:
Thermometer clamp: As shown in Figure 1, 5.
Bushing: As shown in Figure 1, 6 and 7.
Bushing support ring: As shown in Figure 1, 8.
Thermometer depth gauge: As shown in Figure 1, 9. Metal rod: As shown in Figure 1, 10.
2.1.5.6 Grease cup gauge: As shown in Figure 1, 11. 2.2 Aluminum block furnace: The drawing and dimensions are shown in Figure 2. The aluminum block furnace should be equipped with a 750W tubular heater, and the heater current should be controlled to obtain and maintain the required temperature.
3 Operation steps
3.1 Insert an empty test tube into each test tube hole of the can, and insert a thermometer with a range of 5 to 400°C into the thermometer hole. 3.2 Control the heater current and adjust the furnace temperature to the required level of the upper limit temperature of the grease dropping point, as shown below. Furnace
Temperature, ℃
121±3
232±3
288±3
343±3
Upper limit temperature of dropping point, ℃
3.3 Select and use test tubes and accessories 5, 6 and 7 to minimize the swing of the thermometer. Before the test, all parts must be at room temperature. Assemble accessories 5 to 8 to the thermometer in the order shown in Figure 12 Temperature i Assembly, and adjust bushing 7 and bushing support ring 8 so that 8 is about 25 mm away from the end of the thermometer bulb. Place the cup holder 3 in the test tube 2, and then place the thermometer depth gauge 9 and the thermometer assembly in the test tube. Adjust the thermometer so that its ball end is at the bottom of the gauge, and adjust the bushing 6 and the thermometer clamp 5 so that the shoulder of the bushing presses on the edge of the test tube mouth. Use the grease cup gauge 11 to select a grease cup that meets the size of the gauge for the test, and measure the diameter of the small mouth of the grease cup. The National Bureau of Standards issued on March 31, 1983
implemented on December 1, 1983
should meet the size shown in Figure 1.
GB/T 3498-83
3.4 ​​Press the sample into the grease cup from the large opening until it is full. Remove the excess grease with a scraper, so that the grease surface is flush with the cup mouth. The small opening of the grease cup faces downward and is kept in a vertical position. Gently insert the metal rod 10 from the small opening until the rod extends about 25 mm from the large opening of the grease cup. Make the rod contact the upper and lower circumferences of the grease cup at the same time to squeeze the grease in the cup. Use the index finger to rotate the grease cup on the rod and move it downward in a spiral. The cone part of the grease is adhered to the rod and removed. When the grease cup slides out from the lower end of the rod, a smooth grease film with repeatable thickness is left in the cup. 3.5 Take out the thermometer assembly and depth gauge from the test tube, put the grease cup in the test tube, and reinstall the thermometer assembly. There is no need to adjust the position of the thermometer because there is an appropriate gap between the bulb end of the thermometer and the cup mouth. 3.6 Take out the empty test tube from the aluminum block furnace and insert the test tube assembly shown in 13 in Figure 1. 3.7 Record the temperature when the first drop of sample falls from the grease cup, accurate to 1°C. Multiple measurements may be made simultaneously.
４Calculation
Calculate the dropping point, °C, as follows:
Where, Tn—
TT.
Thermometer reading when the first drop of sample falls from the grease cup, °C, furnace temperature, °C,
T—dropping point of sample, °C.
The result should be expressed to the nearest integer.
5 Precision
5.1 Repeatability
The difference between the results of consecutive tests on the same sample, performed by the same operator, using the same instrument, under the specified operating conditions, shall exceed the value given below only once in 20 times. Dropping point of lubricating grease, °C
to 116
116~221
222~276
277~330
Repeatability, °C
When the difference between two determination results obtained is less than the repeatability value of the method, the arithmetic mean of the two results shall be taken as the dropping point of the specimen. :5.2 Reproducibility
The difference between two independent results obtained by different operators in different laboratories using the same specimen shall exceed the value given below only once in 20 times.
Dropping point of lubricating grease, °C
to 116
116~221
222~276
277~330
Repeatability, °C
If each of the two laboratories provides a result that meets the reproducibility requirements, the average of the two results shall be taken as the test result for the specimen.
GB/T3498-
GB/T 3498
Specifications of Thermometer
Range (range)
Graduation value
Immersion depth
5～400℃
76mm
413±5mm
Length of mercury ball
Diameter of mercury ball
13±2mm
5mm
Distance from the bottom of the mercury ball to the 0℃ scale
Distance from the bottom of the mercury ball to the 400℃ scale Each longer scale line represents
Each marked number represents
Maximum error of scale
GB/T 3498- 83
Appendix A
(Supplement)
100 mm
354 mm
1°C below 300°C, 1.5°C above 300°C Additional remarks:
This standard was proposed by the Ministry of Petroleum Industry of the People's Republic of China, and the technology belongs to the Petrochemical Research Institute. This standard was drafted by -- Ping Chemical Plant. 331
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