GB/T 3710-1983 Industrial phenol, Determination of phenol crystallization point

GB/T 3710-1983 Industrial phenol, determination method of phenol crystallization point GB/T3710-1983 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Crystallization point of technical phenol and phenol
Determination method
Method of determination for crystalizing pointof technical phenol and pbenic acidUDC 547·56+668
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GB 3710-—83
This standard applies to the determination of crystallization point of technical phenol and phenol obtained by fractionation of crude phenol from high-temperature coal tar. 1 Principle of the test
When technical phenol and phenol are cooled, the temperature gradually decreases. When it reaches a certain temperature, crystals begin to appear. The heat of crystallization is released, causing the temperature to rise slightly, reach the highest point, and stabilize for a moment, and then continue to decrease. The highest temperature is the crystallization point. 2 Reagents
2.1 Molecular sieve: 4A, powder (not more than 120 months). Before use, burn in a high temperature furnace at 450-500℃ for 2h and store in a coal burner without desiccant.
3 Instruments
3.1 Thermometer: temperature range 0~50℃, scale 0.1℃; temperature range 0～100℃, scale 1℃. 3.2 Product point determination instrument: as shown below.
, 4—cover: tell—beaker! 6—inner tube: 7—outer tube 1—thermometer, 2—precision thermometer 1 3—stirrer, National Bureau of Standards 1988-05-24 issued
1984-05-01 implementation
GB3710—#3
Inner tube: inner diameter 22±1mm, length 155±2mm Outer tube: inner diameter 40±2mm, length 145±2mm Constant temperature bath, volume 1000ml, tall beaker. Stirring rod: Corrosion-resistant metal wire with a diameter of 1 to 2 mm, with the bottom wound into a ring. Magnifying glass: 5 times.
4 Test steps
4.1 Add 20 ml of molten sample at about 60°C to a dry and clean inner tube, add 3 g of sieve, plug the test tube with a rubber chamber, and oscillate vigorously for 5 to 10 minutes while keeping the sample in a molten state. If the sample solidifies, it should be heated and melted. 4.2 Install a stirring rod and a thermometer with a 0.1°C scale, stir and cool, and predict the crystallization point. 4.3 Heat the contents of the test tube to a temperature about 5°C higher than the predicted crystallization point to melt the sample. However, a small amount of crystallization should be retained on the tube wall as a seed crystal. Control the water bath temperature to be 5 to 10°C lower than the predicted crystallization point. Stir the sample slowly (about 10 to 15 times per minute). When the temperature gradually drops to 0.5°C lower than the predicted crystallization point, remove the seed crystal on the tube wall and carefully observe the temperature change with a magnifying glass. At this time, the temperature starts to rise. When the temperature reaches the highest point and stays for more than 1 minute, the highest temperature is the product point. Read this temperature (accurate to 0.01℃), and at the same time record the temperature near the middle of the exposed part of the thermometer mercury column. If there is no temperature rise or the temperature rises by more than 1℃, the test should be invalidated.
5 Calculation of test results
The observed crystallization point temperature is corrected according to formula (1); t= to+4ti+At2
Wu Zhong:
At2 =0.00016Hx(to-tm)
-The corrected crystallization point of the sample,:
-The observed temperature, °C,
The calibration value of the thermometer itself, corrected according to the calibration table, °C; At—The correction value of the temperature of the exposed part of the mercury column, iIs—The temperature near the middle of the exposed part of the mercury column, C; H—The height of the mercury in the exposed part of the thermometer rubber stopper, expressed in degrees, °C. 6 Test error
6.1 The error between the same laboratory and different laboratories shall not exceed the following allowable values:
1 Industry phenol
Additional note:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. Laboratory
This standard was drafted by Meishan Engineering Headquarters and Anshan Iron and Steel Company. The main drafters of this standard are Gu Shiren, Wang Tianyun, Wang Deqing and Peng Xingzi. (1)
Unit: ℃
Non-laboratory
From the date of implementation of this standard, the former Ministry of Metallurgical Industry Standard YB30864 "Industrial Phenol" will be invalidated.
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