A pressure relief valve is a safety device designed to protect pressurized equipment or system during an overpressure event or in the event of vacuum.An overpressure event is a condition, in which pressure inside the equipment or piping system increased beyond the specified design pressure or maximum allowable working pressure (MAWP). If not relieved this can damage the system, property and personal. Similarly, an unwanted vacuum is also dangerous for the system.
The primary purpose of a pressure Relief Valve is the protect the life and property by venting fluid from an over-pressurized system. Vacuum relief valve ensures that vacuum like situation does not occur in the system by allowing air inside the system.