BS EN 50055:1991 Electrical apparatus for the detection and measurement of combustible gases. Performance requirements for Group I apparatus indicating up to 5 % (V/V) methane in air
1999BS EN 50055:1999 Electrical apparatus for the detection and measurement of combustible gases. Performance requirements for Group I apparatus indicating up to 5 % (V/V) methane in air
1991BS EN 50055:1991 Electrical apparatus for the detection and measurement of combustible gases. Performance requirements for Group I apparatus indicating up to 5 % (V/V) methane in air