Pressure relief valves: What makes them different? | Valve Magazine
Apollo Valves 511DDBJMAA0000 3/4 in. MNPT x 1 in. FNPT Sec VIII Liquid Bronze Safety Relief Valve w/ Brass Trim, Screwed Cap, Set Pressure - John M. Ellsworth Co. Inc.
Apollo Valves 16-501-25 1/2 in. Male x 1/2 in. Female General Purpose Liquid Relief Valve w/ PTFE Seats, 50-250 PSI Relief Range - John M. Ellsworth Co. Inc.