Pressure relief valve (PRD) is used to...

• A. Engineered valve or other device used to control or limit the pressure in a system or vessel, by venting excess pressure.
• B. A method of mixing foam.
• C. A type of nozzle.
• D. A container for storing foam concentrate.

Answer: (A)

Pressure relief devices protect systems from overpressure by venting excess pressure when the set point is reached. A PRD is an engineered device placed in a system or vessel that stays closed under normal operation but opens automatically to release pressure that has risen above the safe limit. This prevents damage or failure of pipes, fittings, and equipment. It’s specifically about limiting pressure, not about foam mixing, nozzle function, or storing foam concentrate, which is why it’s the correct description.