Just looking for a safety measure to keep my pump safe if the line should plug for whatever reason (like ice).

I have searched a bit looking for a low pressure safety valve/pressure relief but there doesn't seem to be much out there. My system normally runs about 9 or 10 PSI with all diffusers on. A bit higher when I run just one for this winter so I added an extra line to act as a "bubbler" with no diffuser just stuck down in the water to let the pump run easier by bleeding a bit of pressure off.

What pressure setting would you buy and where can I find it? It would need 1/4 NPT for the easiest plumbing. Searches have turned up a couple but generally there isn't much in the low range that I have found and most have had mixed reviews on quality.

Thanks,
Dan

Are you using a rotary, or a reciprocating compressor?

FWIW I have a Gast 75R (rocking piston) and I have this:

http://store.airmaxeco.com/product/airma...on-system-parts

Pump is a Gast 23 Series oilless rotary vane.

Bill - do you know what pressure that relief is? Their site didn't say.

Just found it - 25 PSI

That seems a bit high? Was thinking it should be no more than 18-20 but trust your advice.

I suspect 25 psi is too high for rotary vane and don't want to steer you wrong. Hopefully, Sprkplug or someone else with rotary vane experience will chime in.

I'm not totally convinced it's necessary, but here is what I have in mind.

http://www.gastmfg.com/product_detail.aspx?ProductID=169&ProductTypeID=41

Bill Cody will know for sure, but I'd suggest 15 psi.

For the rotary vanes I suggest the pop off to be at 15psi. The adjustable psi ones I have from Gast are preset for 15psi & will weep a little air a few pounds before full pop off.

Yep, low pressure relief valves often weep a little. You can get units that will seal better at low psi, but the finer the tolerance the more you will pay.

Thanks for the info - just ordered a Gast AA205 relief valve 2-25 PSI and figure I will set it while the diffusers are running for a bit higher than they require.

To best way to set the adjustable relief valve is have an air pressure gauge on the air manifold, and block all air coming out of the compressor. Air will escape thru the relief valve. Then tighten or loosen the threaded part until you get the desired psi.