The Specialty Mfg. Co. (SMC) offers ball check and relief valves. 490 Series ball check valves feature operating pressures up to 3000 PSI, flow diameters up to 0.280", cracking pressure limits ranging from 1 to 70 PSI, and operating temperatures ranging from -50 to +375°F. Model 667 brass relief valves can handle flow rates up to 4 GPM, and they are constructed from Viton, EPDM, and Buna-N materials.