GB/T 3145-2023Determination of benzene crystallizing point (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents" Drafting.

This document replaces GB/T 3145-1982 "Method for determination of crystallization point of benzene". Compared with GB/T 3145-1982, except for structural adjustment and editing In addition to sexual changes, the main technical changes are as follows:

a) The description and requirements for test tubes in the instrument have been changed (see 5.1, 5.2, 2.1, 2.2 of the 1982 edition);

b) Added requirements for test tube plugs (see 5.3);

c) Added refrigeration equipment as an option for cold baths (see 5.4);

d) Changed the requirements for thermometers in temperature measuring devices (see 5.6.1, 2.3 of the 1982 edition);

e) Added temperature measurement device options (see 5.6.2);

f) Added stirring device options (see 5.7);

g) Added "Reagents and Materials" (see Chapter 6);

h) Increased "hazards" (see Chapter 7);

i) Added requirements for placing thermal insulation materials inside the air casing (see 9.2);

j) Changed the sampling volume in the test procedure (see 10.1, 4.1 of the 1982 edition);

k) The criterion for identifying the crystallization point of water-containing samples in the test procedure has been changed (see 10.4, 4.3 of the 1982 edition);

l) Delete the requirement for calibration of the temperature of the exposed part of the mercury column of the thermometer (see 4.4 of the 1982 edition);

m) Added "Quality Control" (see Chapter 12);

n) Added content on the precision of benzene crystallization point when using a temperature sensor (see 13.3).

Warning

Warning - Personnel using this document must have practical experience in regular laboratory work. The use of this document may involve certain hazardous materials, equipment and operations, this document does not identify all possible safety issues. Users are responsible for taking appropriate safety, health, and environmental measures and ensure compliance with the conditions stipulated in relevant national laws and regulations.

1 Scope

This document describes a test method for the determination of the crystallization point of benzene.

This document is applicable to the determination of the crystallization point of benzene.

2 Normative reference documents

The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, the dated quotations For undated referenced documents, only the version corresponding to that date applies to this document; for undated referenced documents, the latest version (including all amendments) applies to this document.

GB/T 514-2005 Technical specifications for liquid-in-glass thermometers for petroleum product testing

GB/T 4756 Manual sampling method for petroleum liquids

GB/T 6682-2008 Specifications and test methods for water used in analytical laboratories

GB/T 8170 Numerical rounding rules and expression and determination of limit values

3 Terms and definitions

The following terms and definitions apply to this document.

4 Summary of methods

When cooling under specified conditions, when the liquid phase benzene sample is cooled to a certain temperature and the solid phase appears, the temperature rises again, and the maximum temperature reached is The degree is the crystallization point of benzene.

5 Instruments