Historical
BS EN 331:1998+A1:2010
Manually operated ball valves and closed bottom taper plug valves for gas installations for buildings (British Standard)
1.1 This European standard specifies the general requirements for the construction, performance and safety of ball valves and closed bottom taper plug valves. It also details the test methods and marking requirements. It applies to valves for domestic and commercial not directly buried installations inside or outside of buildings, using gases of the first, second and third family (specified in EN 437).
British Standards Institution [bsi]