Griffco diaphragm pressure relief valves are designed to protect chemical feed systems from over pressure damage caused by defective equipment or a blockage in the chemical feed line.. Robust construction ensures reliability in the rigorous service of municipal and industrial applications. Wetted materials include: PVC, CPVC, PP, PVDF, PTFE, 316 SS, A 20 and Hast. C. Available sizes: 1/2" - 2".