Need help with an Air Compressor Pressure Switch!!

[crazycaseys53]

Hey fellas (and ladies),

This is my first post on Garage Journal, though I am a long time poster, trying to contribute over at the Jalopy Journal. Ryan sent me here for help with my air compressor...

Anybody out there know their way around air compressors? Particularly around pressure switches?

I'm finally upgrading (I hope) my old portable Craftsman with an equally old stationary Charge Air Pro unit made by Ingersoll-Rand (Model# 5E6VA; 5hp, SS, 60ga, 240v, 1ph). The compressor is in beautiful shape, but the kid I bought it from had rigged the damn thing every which way, namely, eliminating the unloader valve in an attempt to fix a leaking pressure switch, AND he threw those parts away!

I have a comically large Penn Controls pressure switch and unloader that has the correct cut in/out settings, but I have a question about it's rating. The Penn Controls switch is rated at 3hp @ 240v-1ph, or 5hp @ 240v-3ph. There is NOT an amperage rating. My compressor is 5hp @ 240v-1ph, and the motor is rated at 15A. I imagine a 3hp electric motor of the same vintage as this controller pulling at least 15A, but I'm no electrician.

Can I use this Penn Controll switch on my compressor? I already have it, plus I'm having a hard time swallowing $70-some odd dollars for a Chinese made, mostly plastic replacement for the IR switch, but I also don't want to burn up my motor...or my garage.

Thoughts/help!?

Thanks,
Casey

 

[md21722]

At 15A it's a 3HP motor, not 5HP, so yes. The CFM specs also point to it being a 3HP compressor.

A 5HP would have motor nameplate no lower than 19A and CFM in the 16-20 range.

 

[crazycaseys53]

At 15A it's a 3HP motor, not 5HP, so yes. The CFM specs also point to it being a 3HP compressor.

A 5HP would have motor nameplate no lower than 19A and CFM in the 16-20 range.

I don't know if this image worked in my original post. The dataplate reads 5hp AND 15A; here's a picture:

 

[md21722]

Yeah its from an era of grossly inflated compressor HP numbers. There was a class action lawsuit some years back about it, with manufacturers claiming HP including the motor starter windings or something like that.

This is a 3 HP air compressor. It says its 5 HP, but it's not.

The pressure switch you have is fine.

 

[crazycaseys53]

Yeah its from an era of grossly inflated compressor HP numbers. There was a class action lawsuit some years back about it, with manufacturers claiming HP including the motor starter windings or something like that.

This is a 3 HP air compressor. It says its 5 HP, but it's not.

The pressure switch you have is fine.

Awesome news! I was hoping it was something like that. Umm, any idea about how to wire that Penn Controls switch? I can post a picture of the terminal arrangement when I get home tonight. The immediate difference is there are only 4 terminals vs 6 in the IR switch. The IR switch has terminals for ground, and the Penn Controls doesn't seem to.

 

[md21722]

We will need to see a picture. For ground you can drill a hole for a ground screw and put some lugs on the wires.

 

[jallyn]

Will need more info to be sure but sounds like your 4-terminal pressure switch has two contacts that you will break both legs of the 240 volt supply to the motor.

 

[EOC_Jason]

For the 4 terminals it's just connecting up the two lines to the two loads. Usually there is a threaded hole somewhere on the frame of the box to connect a ground screw, but if not you can just use a short self-tapping or drill your own.

 

[454ragtop]

The 6 terminal switch was most likely to allow use with either single or 3 phase motors, while the 4 terminal would be for single phase only. Do not break the ground thru the switch terminals.

 

[crazycaseys53]

We will need to see a picture. For ground you can drill a hole for a ground screw and put some lugs on the wires.

So here is the pressure switch. I'm assuming the terminal's marked "L" are "line" and the terminals marked "M" are "motor"!?

I'm still unsure about the ground. It just seems sloppy that it wouldn't have a designated spot for it. Am I missing something?

And lastly, the unloader valve has two ports coming off of it. Which one goes to the check valve and what do I do with the other one? I'm sure I'm overthinking this stuff, but I like to TRY and do things the right way...

Thanks for all the help!!

 

[EOC_Jason]

Yes you are correct on the power, interesting how it splits them outer & inner... As for ground I've never seen one that didn't just have a ground screw threaded on the inside of the box the frame.

One port goes to the pump head, the other is where it vents out... Some are threaded like that so you can run a line somewhere (like to an auto-drain that works off of the unloader line)

 

[crazycaseys53]

I don’t mean to revive my own ancient thread, but I’m having some fun new issues with this setup, which makes me think I never had it quite right. Namely, the unloader valve bypasses air constantly past the needle valve and out the threaded port on the top when the compressor is running; it always has. When my pump was healthier, it never kept it from cycling off, at which point everything holds pressure, but now that my pump is a bit more tired, it really struggles to fill that last 20 psi or so against the “leak”.



Should I have air coming out either of these ports when the compressor is running?

Thanks,

Casey

 

[The Cobbler]

not sure why there looks like 2 ports for the unloader line? pretty sure the one you're not using should be plugged . that would solve that leak
the constant bleed would indicate needing adjustment

 

[crazycaseys53]

not sure why there looks like 2 ports for the unloader line? pretty sure the one you're not using should be plugged . that would solve that leak
the constant bleed would indicate needing adjustment

There is a little jet down in there.



I did try adjusting the needle valve until there isn’t any flow out of that end while running, but the flow is still steady out of the top port. When the compressor shuts off (pressure switch kicks in), the little arm pushes the needle valve in all the way. I wonder if I have the pump head plumbed into the wrong port? Maybe it’s supposed to go into the top, and release out of the center port…?

 

[The Cobbler]

take some more pics of the entire plumbing. pump to tank & the pressure switch hooked up

 

[crazycaseys53]

take some more pics of the entire plumbing. pump to tank & the pressure switch hooked up

I do have it backwards…



Thank goodness for the Internet…

 

[The Cobbler]

I've not seen an unloader with the atmosphere port able to be plumbed .
hope plumbing it correctly solves your issue

 

[crazycaseys53]

I've not seen an unloader with the atmosphere port able to be plumbed .
hope plumbing it correctly solves your issue

It worked phenomenally. I feel like such a jerk; I’ve been over-working this pump and motor since 2017. It fills lightning fast now, and generates much less condensation.

 

[The Cobbler]