AirComParts ASME Safety Relief Valve, 1/4 in. NPT, 50 to 325 PSI

Every air receiver needs a safety valve set at or below the tank's maximum allowable working pressure, and it needs enough relieving capacity to pass everything the compressor can produce. These are ASME coded brass pop off valves with a 1/4 in. male NPT inlet and a stainless pull ring for the manual test lift.

Set pressures and relieving capacity

• 50 PSI, 51 CFM (S1032)
• 60 PSI, 59 CFM (S1200)
• 75 PSI, 71 CFM, Viton seat (S1201)
• 100 PSI, 92 CFM (S1202)
• 125 PSI, 112 CFM (S1203)
• 175 PSI, 153 CFM (S1206)
• 250 PSI, 214 CFM, Viton seat (S1207)
• 325 PSI, 275 CFM (S1220)

Picking the set pressure

Two numbers decide this and people usually only check one. The set pressure must not exceed the tank's stamped maximum allowable working pressure, which is on the ASME nameplate welded to the receiver, not on the pressure switch. The relieving capacity in CFM must be equal to or greater than the compressor's output at that pressure. A valve that pops at the right pressure but cannot flow enough air is not protecting anything, and it is the failure mode nobody notices until it matters.

If your tank is stamped 200 PSI and the pump makes 15 CFM, the 175 PSI valve at 153 CFM is correct. Going up to the 250 PSI valve because the pump can reach it would be wrong, because the tank is the limit, not the pump.

Viton on two of them

The 75 PSI and 250 PSI valves use a Viton seat. Viton holds up better against heat and against oil carryover, which matters on a hot discharge line or downstream of a pump that is passing oil. The others use the standard seat and are fine in normal tank service.

Fitting

Thread it into a port on the tank itself or into the discharge manifold ahead of any valve that could isolate it. Nothing shuts off between the safety valve and the vessel it protects. That's the whole point of it. Use sealant sparingly on the male threads and keep it off the last two threads so it cannot migrate into the seat. Pull the ring once after install with the tank under pressure to confirm it lifts and reseats clean.

Replace rather than adjust. These are factory set and sealed, and an adjusted safety valve is no longer a coded safety valve.

Brass ASME coded tank safety relief valves in 1/4 in. NPT, set pressures from 50 to 325 PSI, relieving capacity 51 to 275 CFM, for air compressor receivers and discharge piping.