Curtis Compressor

Just picked up this old compressor. Runs & charges up...needs sprucing up. Any info would be appreciated..especially about changint the oil & bleeding the tank.

Just thought you guys might like to see the compressor I made a couple years ago. Scrap 20 gallon tank and small pump, motor from a yard sale, pressure switch from eBay, and everything else bought locally. I painted it that nice OD green.

is it possible to retro-fit a drain into the bottom of my tank...or is that really pushing it?
I would certainly keep it horizontal if it werent for the drain problem.

The filer is another thing. Compressors need air filters as much as cars or mowers do. I'd try and find one if I were you. Some of the sources I listed in my other post have them. Paper element Solberg filters are best, but I'd use just a simple foam one if you can find them.

Unless you know a certified pressure vessel welder who could put a fitting on the bottom of the tank, don't try. Putting it on end seems like the only option in this case.

The compressor pump reminds me somewhat of a 1954 Brunner I just bought, but not quite. There used to be a fellow named Roger Prosper on this board who could ID any compressor ever made. A little searching through the archives will probably turn up his email address.

What's so special about this "Kunkle" valve? Standard valves with pipe threads are available everywhere.

You want your safety valve to be 20 pounds over the cutoff or it'll blow on its own.

The pulley/speed relationship is direct. If your motor pulley is 3" and the compressor flywheel is 12", then the compressor will turn at one quarter the speed of the motor. I would guess that the pump is supposed to be used in the 450 to 800 RPM range.

The check valve in the pump>tank line is so you can use an unloader in the pressure swtich. The unloader is supposed to be pimped into that line. Unloader blows the line, check valve keeps the tank from emptying out. This whole shebang is there to make it easy for the compressor to start without fighting the tank pressure.

A little rust in the tank is fine--it happens to every compressor. You just don't want it rusted out. There are a couple of failure modes for air tanks. The most common (maybe 90% of the time) is that pinholes develop and let you know it's time for a new tank. The other 10% is more interesting. A big chunk of the bottom would blow out and the thing would either: 1. jump into the air. 2. Split open like a peeled bannana, thoug this is most common when a weld rusts out. How's you tank welded? Both are dangerous to be around.

As far as the blast moving the compressor, think about it. 125 pounds per square inch would exert a quick thrust of of 250 pounds with a 2-square-inch hole in the bottom. Your ~100 pound comressor would be moving.

With 1.5HP you should be good for most any speed you want. Use an ammeter when you have the new pulley on just to be sure, but it sounds good.

McMaster-Carr, Grainger, and Enco all should sell these parts. Check in the yellow pages under compressors, bearings, or power transmission. You'll get stores that sell this stuff that way. Even our local lumberyard carries safety valves here. Try some non-chain places around where you are.

Like the other poster said, there should be a little threaded plug around the base of the pump somwhere. Take that out to drain, put it back in, then fill to the correct level with compressor oil.

For a 125 psi working pressure, I'd get a saftey valve set at 150 psi. Compressor shops, bearing shops, good hardware stores, and supply catalogs like Grainger, McMaster-Carr, and Enco will have them. Even Sears will sometimes carry them. Common parts.