GB/T 2539-2023Determination of melting point of petroleum waxes—Cooling curve method (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 2539-2008 "Cooling Curve Method for Determination of Melting Point of Petroleum Waxes". Compared with GB/T 2539-2008, except In addition to structural adjustments and editorial changes, the main technical changes are as follows.

a) The scope of application of petroleum wax has been changed (see Chapter 1, 1.1 and 1.2 of the 2008 edition);

b) The content of result calculation has been added to "Principles" (see Chapter 4);

c) The table of technical parameters of melting point thermometers has been deleted (see Table 1 of the 2008 edition);

d) Increased the tolerance of some values (see 5.1.2, 5.1.3 and 5.3.1);

e) Added water bath thermometer range requirements (see 5.1.4);

f) Added test tube plug and timer requirements to "Instrumentation and Equipment" (see 5.1.5 and 5.1.6);

g) Added relevant content on automatic instruments (see 5.2, 7.2, 8.2 and 11.2);

h) Added "sampling" and "quality control" requirements (see Chapter 6 and Chapter 10);

i) Changed the content of the "Result Report" and added the requirements for arbitration testing in case of disputes (see Chapter 9, Chapter 8 of the 2008 edition).

1 Scope

This document describes the cooling curve method for determining the melting point of petroleum waxes.

This document is applicable to the determination of the melting point of solid petroleum wax at room temperature. It is not applicable to petroleum grease, microcrystalline wax, petroleum grease, microcrystalline wax and paraffin wax. or the determination of the melting point of a mixture of crude paraffins.

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 27867 Automatic sampling method for petroleum liquid pipelines

SH/T 0229 Sampling method for solid and semi-solid petroleum products

3 Terms and definitions

The following terms and definitions apply to this document.

4 Principles

Place the test tube containing the melted petroleum wax sample and the melting point thermometer in an air bath, and the air bath is placed in a water bath within a certain temperature range. During the cooling process of the specimen, record the readings of the melting point thermometer periodically. When the sample solidifies, the heat of fusion is released, and its temperature change rate decreases. Small, forming a stagnation period on the cooling curve. Calculate the average of 5 consecutive readings where the total difference does not exceed 0.10°C for the first time as the sample melting point.

5 Instruments and Equipment