Primarily Petroliana Shop Talk Forums Shop Talk Petroliana Forums General Petroliana Discussion Another air compressor question

So I got everything all wired up and running today. Running that circuit was a piece of cake. I rewired the on/off box too and mounted that on the wall.

This is an old Kellogg American 2 stage unit with a 50 gal tank. My question is right now it is kicking off at 130psi on the dot. Being a 2 stage unit, shouldn't it be set to kick off at around 150-160psi? The tank says working pressure (WP) to 200 so I assume 150-160 should be no problem. Does anyone know how to change this?

The wiring should be attached to a pressure regulator mounted on the compressor.. If you take the cover off, there should be a spring looking affair in there and you can tighten it up a bit to increase the pressure. Go a little at a time.
KEVIN

Chris,
Most of the K/A compressors came with a Square D pressure switch.
If your switch has two springs, a tall one and a short one, then the short one should be the high pressure setting.
Before you push the pressure up you may want to check the range on the safety release valve.
Square D has some good technical info on their web site, does take some work to get to it.
Ed

Ed,

My compressor does have the Square D switch and I remember seeing the springs in there when I rewired it. How would I check the range on my safety release valve?

Thanks
Chris

One thing to consider when going with a higher pressure. Your compressor has to work harder. Two stage compressors usually have a higher cut-out pressure but I turned mine down because it really starts to move around to make that extra pressure.
Mike

Mike, what did you turn yours down to? I'm not planning on going to a 175 PSI cut off like a lot of 2 stage compressors are set to, but I feel like since it is a 2 stage it should be at least around 150 or so with maybe a 110psi low pressure start up?

When I got mine it was at 175 psi. I went down to 150 psi cutout and 120 psi cutin. It was really moving around to make that last 25 psi. I am sure mine could use a rebuild. I just had a thought. You said that your pump was recently overhauled. Maybe they turned down the pressure for a break-in period on the pump. I don't know if pumps are like car engines and require a break-in period? Here is a picture inside the cover of my pressure switch showing how to adjust it. I don't know if they are all the same or not.
Mike

I ended up turning mine up to about 155psi cut out and 120psi cut in. Compressor runs nice and slow, quiet, and puts out all the air I think I'll ever need. Thanks for all your help guys, this is what this site is all about!

Chris, just take my word for it- -I have worked on many an air compressor. You are better off leaving the cut-in and cut-out pressures where you have them. Those older K/A two stage units are wonderful. I doubt that you are suppling a large quanity of air to anything. The statements about working hard to get those extra pounds of pressure are correct. No one has even mentioned the fact that your amperage draw will increase with this strain which in turn affects your electric bill. Thanks, David

David,

Do you mean leave them at 155 and 120, or turn them back down? They were at about 130 and 90.

Thanks

Chris, as you stated, yours seems to be running nicely at the 155/120 settings. If it doesn't sound like it is straining at the last 10 or 15 pounds of pressure build-up, and you say that you have seem to have all the air you may need, then leave it there. As I stated, if it sounds like it is straining, it probably is and your current/amperage draw is comparably rising. If you have access to an induction ammeter you could see this happening. You're "draw-down time" will depend on the size of your tank, and a 50 gallon tank is a nice size for home use. The picture by bruzer75 is good and helpful. I used to run rebuilt compressor units under "no-load" for different time intervals before running them at different stages of back pressure after a rebuild. Thanks, David