PRESSURE RESTRICTING DEVICES

A pressure restricting device  is designed to limit the residual pressure available at hose valves or outlets to a safe and manageable level during operation, without reducing static pressure under non-flow conditions. Unlike pressure reducing valves, these devices do not regulate downstream pressure continuously but instead restrict the flow only when water is discharging. Their purpose is to prevent excessive nozzle pressure that could endanger firefighters or damage hose lines in high-pressure standpipe systems. Pressure restricting devices are commonly used on Class I and Class II hose valves located on upper floors of high-rise buildings, where system pressures can exceed  allowable limits. They may take the form of removable inserts, adjustable flow restrictors, or factory-set mechanical limiters, providing a simple, reliable, and code-compliant means of controlling hose stream pressure without affecting the system’s static performance.