Describes requirements for construction and testing, and test methods that apply for detection and measurements of combustible gas or vapour concentrations with air. The apparatus designed for use in potentially explosive atmospheres and in mines susceptible to firedamp. The Standard is supplemented by the following Standards, concerning specific requirements for various types of apparatus. Applies to combustible gas detection apparatus which provide an indication, alarm and/or other output function, to give warning of potential explosive hazard and to initiate automatic or manual protective actions.