Thermoplastic [PVC, CPVC, Glass-Filled Polypropylene, or PVDF (Kynar)] pressure relief valve, [ 1/2" through 1"] NPT threads, is to be of the in-line porting design and feature a molded, fabric reinforced [EPDM or Viton] rolling diaphragm as the primary seal preventing liquid from leaking to the exterior of the valve. The pressure adjusting bolt and lock-nut are to be all plastic to provide added corrosion resistance.
Valve is to have Fail-Dry(r) Safety Design which incorporates a vented chamber between the rolling diaphragm and a secondary flat diaphragm. The vented chamber has an 1/8" NPT port so that thermoplastic tubing, if desired, can be piped to a remote safe location in the event of concern with leakage of dangerous liquids or vapors.
Manufacturer shall, at the factory, set the pressure relief valve at [specify between 5 and 100] PSI. All units are to be 100% individually tested at the factory. As manufactured by Plast-O-Matic Valves, Inc., Cedar Grove, NJ.