BS 7156-2 1990 Edition, September 28, 1990
Respiratory Protective Devices: Threads for Facepieces Part 2: Specification for Centre Thread Connection
Includes all amendments and changes through Amendment 1, January 15, 1993
Additional Comments: W/D S/S BY BS EN 148-2
Published By:British Standards Institution (BSI)
Does not apply to diving equipment or to positive pressure demand breathing apparatus.