The Globe Model G-3 Dry Pipe Valves are the vital control unit in dry pipe automatic sprinkler systems, where supervisory air under pressure is used to prevent freezing that would certainly occur with ordinary wet pipe systems. The Dry Pipe Valve is the connecting link between the source of water supply and the automatic sprinklers, and must react promptly when it receives a signal from the protected area that a fire condition has developed and water is therefore quickly needed. This signal is generated by the opening of one or more sprinklers, which causes a quick, drop in system supervisory air pressure resulting in a loss of the differential ratio. The single clapper assembly design in the Globe Model G-3 Dry Pipe Valves provides several areas exposed to working pressures, which, in combination, create a differential force ratio between system air pressure and water supply pressure. A single-latching lever is provided as a means of holding the clapper in "set" position. Once the valve has operated, a special latch holds the clapper open until manually reset by experienced personnel. The body of the Dry Pipe Valve is constructed of high tensile strength cast iron having considerable ductility to reduce damage in field handling.
All interior operating parts are machined from highly corrosive resistant copper alloys, each having high strength and good wear resistance. Rubber parts are of selective materials, which have good abrasive resistance and long life expectancy in terms of resiliency.