Air Pressure Control Switch Replacement

by Ken

Maybe a snap on compressor?

Maybe a snap on compressor?

Could you please help me with selecting a correct Air compressor switch for a older dual tank compressor that I am repairing. There is no identification tags or stickers to identify the compressor type or model. I was told it is an older snap on unit.

It appears the compressor had a switch with a range of 90 cut in pressure to 120 cut out pressure.

The electric motor is a 2 hp 115 volt rating. The current air pressure switch does not have the value that releases pressure from the pistons for the restart cycle (Unloader valve).

The current switch (has no cover) looks like an older Square D with a auto/off cut-out lever.

There is only one threaded connector from one of the tanks to the switch.

My main question is which model of Square D could I use to replace mine? Could I use a switch with a Unloader valve and disable the valve? Any suggestions would be great.
Your help on this is very much appreciated.
Thank you,

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Apr 07, 2018
Pressure Control Switch
by: Bill

Ken, looking at the photo you provided, I am certain that this compressor has an unloader valve of some sort.

If it does, and it is not attached to the current pressure switch, knowing how it unloads would sure help.

However, if you simply buy a pressure switch that has an unloader valve as part of it's function, one that has the same voltage, same (or close) pressure range, that it does not have a line from the tank check valve to unload the piston doesn't mean you cannot use it.

As long as the tank has a check valve in it, then even if the unloader in the pressure switch is open to atmosphere, as it would be when the pressure switch is off, then no air would come out, as it would be locked in the tank by the tank check valve.

Where is the unloader now? Can you find it?

If so, please start a new thread in this same forum, use the same title as this, and indicate the photos are for this thread, upload up to 4 photos of the area where the unloader is, and we'll have a further look.

Apr 06, 2018
Unloader Valve switch question.
by: Ken

Thanks for posting my question Bill.
I did read over carefully the link about choosing a switch on the website before posting my question. However it did not clearly answer the question of could I use a switch with a unloaded valve and disable the valve or just not hook it up.
Seems like most of the switches available especially on Amazon now have an unloader valve. Please if anyone could answer that main concern this would give me a starting point.
Thanks again.

Apr 06, 2018
Buying a pressure switch...
by: Bill

Ken, sure, here you go...

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