What is the required temperature of crystallization point in industrial naphthalene standard?

Naphthalene products include industrial naphthalene and refined naphthalene. According to the different distillation processes of coal tar, the raw materials of industrial naphthalene include naphthalene oil fraction, naphthalene washing mixed fraction and Phenol Naphthalene washing three mixed fraction. The extraction process of industrial naphthalene also includes double furnace and double tower, single furnace and single tower and pressurized distillation. The refining rates of industrial naphthalene are ≥ 97% (naphthalene oil fraction), 96% ~ 97% (naphthalene washing mixed fraction) and 94% ~ 95% (Phenol Naphthalene washing three mixed fraction), respectively. See the national standard gb6700-86 for the industrial naphthalene product standard.

The crystallization point test of industrial naphthalene adopts GB / t3069 2. According to the standard requirements, SH406B automatic crystallization point instrument is in strict accordance with GB / t3069 2 this standard is designed and manufactured for 7-inch TFT color LCD display; Refrigeration mode: totally enclosed high-efficiency refrigeration compressor. Detection method: imported PT100 temperature sensor, which can store historical data after upgrading for easy query; At the same time, it can be equipped with U disk output function.

    In GB / T3069.2 the reading accuracy of naphthalene crystallization point is required to be 0.01 ℃, and the difference of repeatability test results shall not exceed 0.05 ℃. SH406B automatic high-precision crystallization point instrument fully meets this requirement. In the standard gb6700-86 of industrial naphthalene, the crystallization point temperature requirements of industrial naphthalene are as follows:

The temperature of crystallization point shall be ≤ 78 ℃