BS EN 50241-1:1999 Specification for open path apparatus for the detection of combustible or toxic gases and vapours - General requirements and test methods
2010BS EN 60079-29-4:2010 Explosive atmospheres - Gas detectors - Performance requirements of open path detectors for flammable gases
1999BS EN 50241-1:1999 Specification for open path apparatus for the detection of combustible or toxic gases and vapours - General requirements and test methods