continuous run - constant speed compressor

The OEM solution is to use a standard pressure switch that drives a normally closed solinoid air valve. The released air from the energized/open solinoid valve passes through a spring loaded pressure relief valve on its way to the unloaders on the cylinder leads. I would like to get the electrics out of this system.

I need a source for a mechanical/pneumatic switch. I think it would need a "snap action" on or off.

I think this is the valve that you need .

It does the same thing as an air governor on

a truck , but is for slightly higher range .

george

• surplus center

I didn't think to look at my Surplus Center Catalog and I just recently ordered something from them. I have a couple of similar catalogs I will check out as well.

I didn't particularly like this sentence in the discription: "Once tank reaches full pressure incoming air from compressor is vented to atmosphere". I don't want to waste air but I guess a check valve on the air receiver would eliminate that. If the Surplus Center valve can run with the waste port plugged, it might be satisfactory. I would like to see a schematic. I also need to know if it is fully on or off.

I know that there are some knowledgeable people in the Surplus Center workshop. I might call them tomorrow.

I have one of their compressors , bought it 35+ years ago to put on my service truck,it has an unloader and control. the control looks like a relief valve but instead of air blowing to atmos it goes in a line to operate the unloader valves.

george

Dave

I do have an extra compressor and governor around here but did not bother to look at it My recollection is that it fits the manifold of the compressor and would be difficult to adapt to a pipe thread connection. I suppose I ought to take a look.

I think a few of us have seen those big vertical single cylinder compressors used in factories. We have also heard them load and unload. Those days of thumping, floor shaking, big bore compressors may have passed. I am assuming they have the pneumatic unloader switch that I want.

I can pretty much guarantee that the setup in the picture is NOT a factory Kellogg design. If you look closely, you will see that you already have the spring loaded unloader valve on your machine already. The top part of the assembly with the copper line coming out of it is a pilot valve, with the pressure regulating screw at the top. If you want more pressure, screw it in, less pressure, back it off. I'm not sure about this particular valve, but there is probably a way to set the range as well, most likely by adjusting the larger of the two hexagonal fittings. You can take it off when the tank is blown down and have a look at the insides, you will probably see a ball bearing sitting on a brass set, or something, with a spring to set the pressure at which it opens.

The constant run feature is an either/or proposition. If you close the small manual valve to the pilot valve, the compressor will run off of the pressure switch. If you open the small manual valve, the compressor will run off of the pilot valve, but ONLY if the pilot valve cut out is set LOWER than the pressure switch cut out, otherwise, the pressure switch will still be in control of the situation.

My theory is that two possible things may have happened: either the pilot valve failed to seal at some point and leaked air continuously, necessitating the installation of the solenoid, or, the pilot valve is opening at too low a pressure, either due to wear or maladjustment.

Of course, if you have owned this machine from new , and it WAS always wired this way, I guess I am just full of it.

I'm not convinced that the mounting of the whole affair to the tank is kosher either. Looks like someone drilled and tapped the bolt holes, then sealed the plate to the tank with a gasket. Don't let the blue paint fool you, it's not factory Kellogg blue, which is much lighter and more metallic.

If I am wrong about this valve, or if it is inoperable, you can replace it (and the electrics), with a pilot valve like the one in the photo. Click on the link for more info.

• P25 Pilot Valve

This compressor is new to me. It, and a parts machine, came out of a boiler/chiller room in an electronics factory. A remote 500 gal receiver was included.

I want to eliminate the automatic stop/start function because I will be running the 230/460V motor on 50-55 amps of 208V. I'll control with a #3 starter and remote push buttons. The compressor will only be used on job specific tasks with a duty cycle approaching 90%.

I removed a low crankcase oil sensor and a high-temp discharge safety switch. They were wired in series with the pressure switch. The little manual valve that fed the pilot valve was closed. It didn't occur to me that the existing pilot valve could handle the unloaders by itself. I assumed there would have to be something that forced a strong make or break air signal and incorporated a small vent to depressurize the unloaders. That would be something like a shuttle valve on an air brake governor.

I'll be testing in the next few days with the existing pilot valve..