Compressor pressure switch

[DavidR8]

I have an older Speedaire 2hp compressor.
The built-in pressure gauge only shows 70psi when the switch cuts off.
I don’t see any way to adjust the cutoff pressure so I’m guessing that the switch need to be replaced to get 125psi?

 

[matthewsx]

Have you verified the gauge?

 

[DavidR8]

Have you verified the gauge?

I haven’t but that’s a good idea.
I’ll pick one up tomorrow.
My plan was to try this pump and motor combo out on my 20 gallon tank while I search for a 60 gallon one.
Maybe I’ll start collecting the parts necessary for that, starting with a new pressure gauge.
I’ll need it to sell this compressor no matter what.

 

[Eddyde]

There usually is an adjustment screw of some sort on those switches but the spec plate on that one seems its made for only one pressure? Did you try opening up the switch and looking inside?

 

[DavidR8]

There usually is an adjustment screw of some sort on those switches but the spec plate on that one seems its made for only one pressure? Did you try opening up the switch and looking inside?

I did pull it off the mount but couldn’t see a way to adjust it.
I suspect the gauge my be the issue as @matthewsx pointed out.

 

[aliva]

I have one of these on my system been working fine for over 30 years. We used a lot these were I worked. never a failure.

Externally Adjustable Electromechanical Pressure Controls | Allen-Bradley

Our Bulletin 836T externally adjustable electromechanical pressure controls meet the traditional requirements of the transportation and machine tool industries.

www.rockwellautomation.com

 

[DavidR8]

I pulled the gauge off my portable compressor and the pressure switch is working just fine. Cuts off at 130psi.
New gauge ordered.
Thanks all!

 

[darkzero]

New gauge ordered

Nice easy fix! The gauge you have now, is it oil filled? If yes, could be an even easier & cheaper fix. Oil filled gauges sometimes need to be vented periodically due to climate changes.

My current air compressor I bought an oil filled gauge for it. Didn't come prefilled so I filled it up with glycerin to the appropriate level & thought nothing of it. Fast forward to 6 or 7 yrs later, I noticed the gauge wasn't reading as high as it should. Noticed it looked overfilled too but I haven't touched it since. My pressure switch is adjustable (high & low cutoff) & that's what I thought to do also. But all the other gauges on my air system all read fine (none of them are oil filled).

Turns out my Wika gauge has a ventable plug. Flipped the lever to vent & then the gauge was reading normal again. Some gauges have a little nipple on the plug that you can cut. Or you can vent by slightly lifting the plug. Only other oil filled gauages I've ever had were for cars, I never knew about venting them.



The pic I found online where I learned this.

 

[Harry Knutz]

For future reference, Their is usually a coil spring inside of the enclosure with a stud and nut, Tightening the nut increases pressure and loosening it decreases pressure.

 

[DavidR8]

Nice easy fix! The gauge you have now, is it oil filled? If yes, could be an even easier & cheaper fix. Oil filled gauges sometimes need to be vented periodically due to climate changes.

My current air compressor I bought an oil filled gauge for it. Didn't come prefilled so I filled it up with glycerin to the appropriate level & thought nothing of it. Fast forward to 6 or 7 yrs later, I noticed the gauge wasn't reading as high as it should. Noticed it looked overfilled too but I haven't touched it since. My pressure switch is adjustable (high & low cutoff) & that's what I thought to do also. But all the other gauges on my air system all read fine (none of them are oil filled).

Turns out my Wika gauge has a ventable plug. Flipped the lever to vent & then the gauge was reading normal again. Some gauges have a little nipple on the plug that you can cut. Or you can vent by slightly lifting the plug. Only other oil filled gauages I've ever had were for cars, I never knew about venting them.

View attachment 450083

The pic I found online where I learned this.
View attachment 450084

Thanks Will, what's the advantage to gyycerin filled gauges?