... gong,short pipes,ball valves, retarding chamber,etc Wet Alarm Valve Wet automatic water spraying system is one of most widely ... and automatic fire extinguishing. It is composed of ZSFZ wet alarm valve, water motor gong, retarder, pressure switch, water flow indicator, ... Pressure (Mpa)External Diameter of Flange (*B mm)Middle Diameter of flange screw hole (*B mm)Screw hole numbers & Diameter (n ...