BS EN 50056:1999 Electrical apparatus for the detection and measurement of combustible gases. Performance requirements for Group I apparatus indicating up to 100% (V/V) methane in air
1999BS EN 50056:1999 Electrical apparatus for the detection and measurement of combustible gases. Performance requirements for Group I apparatus indicating up to 100% (V/V) methane in air
1991BS EN 50056:1991 Specification for electrical apparatus for the detection and measurement of combustible gases. Performance requirements for Group I apparatus indicating up to 100 % (V/V) methane