PRD and PRV are generally used only on which type of standpipe systems?

• A. Manual standpipe systems
• B. Combined systems
• C. Automatic standpipe systems
• D. None

Answer: (C)

The need to control pressure in automatic standpipe systems is the key idea. In these systems, water is kept under pressure and can push through the piping and hose outlets with significant force, especially in tall buildings or with long risers. A pressure reducing valve (PRV) or pressure relief device (PRD) is used to bring that pressure down to the system’s designed level. This protects the piping, fittings, and hose connections from overpressure, and it helps ensure that the discharge at the nozzle remains workable for firefighters when they stretch a line. Manual standpipe systems are operated by firefighters and generally don’t require automatic pressure reduction, because the operator can regulate the flow and pressure as needed, so a PRV is not typically installed there.