Changing pressure switch value.

by John Hill
(Napa Valley, CA)

I want to run two compressors in series. One has a high pressure cut off of 100lbs. and the other 145. I need to lower the 145 to 100 so the pressure relief valve in the smaller compressor doesn't blow.

I need the combined storage 80gal. and CFM, about 16.5, to run my sandblaster without constantly having to stop to let the pressure come back up.

Is the pressure switch adjustable or if fixed how are they set at the factory?? Any info appreciated. It is a DeVilbiss 60 gal. oiless.

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Bill answers...

Hi John. It's been a few years since my wife and I spent some time in your backyard, Napa Valley. Nice place in the world you live!

I'm not sure that your PRV would blow at 145 PSI, so if that's the only reason for changing the pressure switch settings, you may not have to. Only one way to find out...right? Test it.

I've uploaded a photo of the innards of the pressure switch on my compressor.

You can see (actually, you can't see 'cause they are covered in sealant) at this end there are two nuts. One adjusts the high pressure cut-out, the other the low-pressure cut-in.

They are often sealed, as mine are, so that the factory knows if you've been messing with the settings, should you ever need to take your unit in to the shop.

John, you'll have some plumbing issues to consider when joining two tanks together.

Cheers,

Bill