Control Valves

Control valves in fire protection systems serve the essential function of regulating and isolating water flow to sprinkler piping, ensuring reliability while allowing for maintenance and testing. The two most common types are Outside Screw and Yoke (OS&Y) gate valves and butterfly valves. OS&Y gate valves use a rising stem that visibly moves upward when open and downward when closed, providing clear visual indication of valve position. Their seating design relies on a wedge-shaped gate pressed against resilient seats, ensuring a tight seal when closed. Butterfly valves, by contrast, use a quarter-turn disc with resilient elastomer seats or seals that provide efficient shutoff in a compact design.

NFPA standards require control valves to be of the indicating type, meaning their position can be easily verified. OS&Y valves inherently meet this requirement, while butterfly valves employ a permanently mounted position indicator, typically a gearbox with a visible window or pointer. Both valve types must also be equipped with tamper or supervisory switches that signal to the fire alarm system if a valve is closed or improperly positioned, thereby preventing unauthorized or accidental impairment. Together, these features ensure that fire sprinkler systems remain ready and fully operational.