GB/T 42368-2023Determination of explosion limits of combustible vapors and gases at elevated temperature and pressure (English PDF)

Foreword

This document was issued on 17 March 2023 by the State Administration for Market Regulation; Standardization Administration of the PRC and takes effect on 1 October 2023.

It is a GB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

1 Scope

GB/T 42368-2023 covers the measurement of the upper and lower explosion limits of a combustible gas or vapour mixed with air at a stated initial temperature and initial pressure — the principle, in which a known volume fraction is premixed in a reaction vessel, ignited by electric spark or hot wire, and judged by the pressure rise that follows; the test device, its reaction vessel, ignition unit, pressure measurement, gas distribution and temperature control; the test steps, prefaced by the warning that the vessel is never opened while under pressure; the processing of the data, where a pressure increment of at least 5 percent of the given initial pressure counts as flame propagation and therefore as an explosion; the safety measures; the calibration of the device, with pressure and temperature sensors verified at intervals of no more than 3 months; and the test report. Appendix A illustrates a device. Limits quoted at ambient conditions widen once a process runs hot and pressurised, so a purge calculation or a relief design based on ambient figures can leave a plant inside the explosive range while its paperwork says otherwise. Written for process safety engineers, chemical and petrochemical operators, and laboratories that issue flammability data.

This document describes a method for the determination of explosion limits of the

combustible mixture of combustible gases (vapors) and air at a given initial temperature

and initial pressure.

This document applies to the determination of explosion limits of combustible gases

(vapors) under the conditions of initial temperature below 200 °C, initial pressure below

1.0 MPa (absolute pressure), and maximum explosion pressure not greater than 15.0

MPa (absolute pressure).

This document does not apply to the determination of explosion limits of chemically

unstable gases or mixed gases in which components may react with each other.

2 Normative references

The following documents are referred to in the text in such a way that some or all of

their content constitutes requirements of this document. For dated references, only the

version corresponding to that date is applicable to this document; for undated references,

the latest version (including all amendments) is applicable to this document.

GB/T 12474, Method of test for explosion limits of combustible gases in air

GB/T 16425, Determination for minimum explosive concentration of dust clouds

GB/T 21844, Standard test method for concentration limits of flammability of

chemicals (vapors and gases)