Air Compressors

I've got this love for air compressors for some reason and recently broke the curse of the unlucky number 13 by getting 3 more of the jewels....now having 16 air compressors from sallvage projects. They all need some attention from minor to major of course and it's intriguing to make them run. My recent project came with the warning..."It won't quit running". First, I found that the pump would fill the tank but I couldn't get any air up to the gauge body/outlet. Yep...orfice plugged with dirt from the inside. (ODD) Then after replacing a rusted outlet pipe (not related to the problem) and fixing the stuck points on the switch, I can compress air but relief valve will blast off before the switch shuts down the action. There is no visible means of adjusting the cut-in / cut-out relays; causing me to wonder if some pressure switches are preset to a certain unchangeable mode at the factory. I'm still searching online but invite some wisdom/comment on this subject. Thanks guys. (Full of Christmas goodies I am)

Yunkman,

Are the contacts where the motor is turned off/on in the pressure switch box are they in another box? Presumably the contacts have an air line running to the box as a pressure sense line? If the box with the contacts doesn't have an air line to it, you might have a setup where the pressure switch was remote mounted. In this case, the contacts that control the motor would be controlled by a magnetic relay that used 120 VAC or some lower voltage DC, like 24V.

If the pressure guage line was plugged with dirt on the inside, the line going to the pressure switch may also be plugged. You might even have to take apart the pressure switch itself to make sure the diaphragm is working correctly and air is getting right to the diaphragm.

A few photos would help the troubleshooting effort a lot!

Jon.

Thanks boys, for the tips. Although I blew out the pressure switch, I didn't take it apart to make sure the diaphragm was in operating order.
A picture will be forthcoming.

i'm not sure about compressors, but torch regulators once had little rebuild kits

Originally Posted by Ironhunter

I am kinda ignorant about compressors but cant you just buy a new pressure valve?

that would take all the fun out of it. You wouldn't learn any new words or nuthin! ; )

there should be a spring in the pressure switch that is bolted into place if there is loosen the bold and that will make it easier for the pressure to trip i used to have to adjust the pressure switch on my well pump and it was the same type as most compressors i have dealt with

If its the generic sort, the black plastic box needs to be on the unit for the switch to operate.

Mine got broken around where the screw is that holds it in place, now I have it all taped up so the box won't shift upwards & the motor stop.

Do you have a way of testing the tanks? I don't know how often they should be checked, or how common it is, but when one lets go, it can be quite devastating.

Yunk,

Idaho makes a good suggestion about pressure testing the tanks. Especially if you are gonna resell them as operating compressors. Test the tank and safety relief valve setting. Old tanks can get pitting inside from water condensing out of the air and cause rust pitting in the bottom of the tanks. Regarding the relief valve, the testing should at least demonstrate that it works-or not!

The tank can be pretty easily tested by filling it with water and then bringing the pressure up to 1.5 times (this may not be the exact number, I seem to remember it can be from 1.3 to 1.8 times) the operating pressure with compressed air or nitrogen. The water is there so you only get wet if the tank ruptures. It is safer than using only air because the air can act as a massive spring, causing all sorts of bad things if the tank lets go. The little bit of air you use on top of a tankful of water doesn't have anywhere near as much energy stored in it.

Sometimes the tank has a nameplate tack welded to it, showing the rated operating pressure and who made the tank, the date, etc. You can use that to see what you need to pressurize the tank to. I don't think the small commercial compressor tanks are required to have this plate, but anything 12" in diameter and over need this plate.

The usual disclaimer...I'm not a pressure tank design expert, having only done projects where I requested help from said experts!

Have fun,
Jon.

Hey, I found a set screw under a transparent/yellow plug. Been too busy hauling iron to work on it again but I'm still going to send a picture and results when I get around to it. Need to chip the JB Weld off the Relief Valve stem. I know it works b/c it blew at whatever it's rated at. Relatively a newer tank. Have to make music for the coming in of the New Year. See ya then and y'all be safe.

all the bad words I ever learned came from two places... Golf with my grandfather, an building things on my own( instructions, or not, built from my head or a box!).

Err..an good luck with compressor collection!

Sirscrapalot - I'd still like a picture, an some are worth 10,000 words if she catches you taking it.