ASME Safety Relief Valve, 1/8 in NPT, 250 PSI, 118 CFM

An ASME coded safety relief valve set at 250 PSI with a 1/8 in NPT connection. It is the smallest port size in the range and suits small receivers, pilot and control circuits and equipment where there is no room for a 1/4 in valve.

Specification

• Part number: S1221
• Connection: 1/8 in NPT
• Set pressure: 250 PSI
• Capacity: 118 CFM
• Code: ASME coded

Sizing a safety valve properly

Two things have to be right, and people usually only check one. The set pressure has to be at or below the maximum allowable working pressure of whatever it is protecting, and the capacity has to be at least the full output of the compressor feeding it. A valve with the right set pressure but not enough capacity will lift and still let pressure climb, which is the failure mode you least want.

At 250 PSI this is a high set pressure valve. It is not the part for a 175 PSI shop receiver, where a valve set at or just above the tank rating is what you want. Check the data plate on the vessel before you choose.

Fitting it

Fit it directly to the vessel or line it protects, with nothing that can be shut off between the valve and what it is protecting. No valves, no restrictions, no long runs of small tube. Keep the outlet clear and pointed somewhere safe, since it will discharge hot air at full pressure without warning.

Use pipe thread sealant sparingly on the threads only and never on the seat. Do not tighten by the body cap, and do not adjust or dismantle an ASME coded valve: once the seal is broken the code rating goes with it.

Testing and replacement

Lift the test ring periodically so the valve is known to be free, on a tank at pressure and with eye and ear protection on. If it weeps after testing, replace it rather than tapping it; a seeping safety valve is telling you the seat is damaged.

Related parts

We also stock ASME safety relief valves in 1/4, 1/2, 3/4, 1 and 1-1/4 in in a range of set pressures, Kunkle 6010 valves for larger systems, discharge check valves and pilot unloader valves.

Not sure which one

Tell us the vessel rating from the data plate and the output of the compressor feeding it, and the Warthog Air Compressor Store team will confirm the right valve before you order.

ASME coded safety relief valve, 1/8 in NPT, 250 PSI set pressure, 118 CFM capacity, for small receivers and control circuits.