Dual Pressure / Vacuum Relief Device
The Dual Pressure/ Vacuum Relief Device is a combination of the 5810B / 5820B Series Relief Valve and Flame Arrester and the Safety Selector Valve.
Digester and gas holder covers should be equipped with pressure and vacuum relief (PVR) valves for protection against structural damage caused by possible over and under pressure due to the rapid pumping of the sludge into and out of the vessel, or from an excess of gas production. The valves are installed with flame arresters to prevent an external flame from igniting the gas within the digester. The DPRV also comes with a safety selector valve that allows switch-over between the two devices to allow for continuous system overpressure protection.
Water Environment Federation, Manual of Practice (MOP) No. 8 recommends redundancy to ensure that the digester is protected even during maintenance.