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recommissioning an ingersoll t30

tomjelly

Stainless
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Aug 26, 2007
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GA
New to me IR T30 with 2545 pump with after cooler, 10hp, horizontal, 120gal circa 1997, was not in service, nobody to ask why. At some point the motor was replaced and with it the control box that had the model and serial #. Apparently a lot of minor variations in these over the years so difficult to get the specific parts manual. In any case in checking this out I needed to replace a few damaged copper lines and discovered the check valve guts had fallen apart or been removed (Maybe why the motor was replaced?) and there was no air unloader connection on the pressure switch, and there was no line on a fitting from what I think is the unloader port from the low pressure cylinder head. Speaking with someone at IR (who wasn't really able to help without a model #) and they said it might have a centrifugal unloader- but the ones I've been able to find photos of on the web LOOK (not many good pics) like the missing line I have is supposed to go to the pressure switch. I'm not even positive that really is a port able to be used for unloading rather than the the usual port on the check valve type of unloader. I've heard that some just unload back into the air filter. Soooooo..... anyone an expert on these that could shed some light on this or do I just plug it in and see if air comes out of that un loader port and if it does, replace the pressure switch with one with an unloader port? Or plug that line, get an unloader style pressure switch and run its line to the check valve port? I'm still wondering why it has a pressure switch without an unloader port and an unoccupied fitting on the head, unless there was some sort of electric solenoid valve unloader...
 
photo of empty fitting, possibly for connection to pressure switch or does this unload internally to air filter?, and a photo of the front cover, or is this a centrifugally unloaded pump?
 

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The T30 has been made in so many sizes and variations over so many years, it's difficult to troubleshoot. Your plumbing looks nothing like mine. A friend has an old single stage high volume version which is yet again different

jack vines
 
That Furnas pressure switch *should* have the unloader valve in it, at least all I've seen did. But then most of the ones I've seen were on smaller compressors. Pop the hood and see - if there's a 1/4" inch line on one end and a larger NPT in the middle then it's what I've seen, the 1/4" line is the unload line.
 
That '02 has tube configuration a lot different than mine... My pressure switch definitely does not have an unloader. Further research shows that part number of furnas switch does not have one, they come in many configurations too. I'm going to pressurize the tank a bit to keep the check valve closed, then take a blow gun and blow some lower pressure air back thru the unloader port on the check valve and see that air comes out of that unoccupied port in the head. If so, I would think that would function properly as a line to a pressure switch with an unloader which I'd need to swap with the one currently mounted. If not I'll need to fire it up and see if air comes out of that port continuously (which would mean I need to investigate more but would probably mean it needs to go to a pressure switch with an unloader) , or if not and it flows only when the compressor shuts off maybe it just had a diffuser or something on it and it is just the exhaust of some internal unloader mechanism. Then I'd need to check to see if there is any pressure in the outlet line still that might be being held by the high pressure side as its possible that I might need to connect both the check valve port and that unoccupied port together with a tee and then to a pressure switch with an unloader
Unless someone has a better idea...
 
I generally run one of those cellphone borescopes in any tank I get in here to have a look before pressurizing...
 
So when the tank is pressurized I can't get any air backwards into the pump from the pump side of the tank check valve. Makes sense, I guess. I put some pressure to the unoccupied port and there is a shuttle valve in the head that moves forward towards the air filter when I do that. Its free floating, no spring or anything, and I can push it back easily with my finger when I remove the pressure to it. The line under the air filter port is just open to the air filter side of that valve and whatever comes out of it (or goes in) would be free to come thru the filter. I was able to find a diagram that is close to what I have but of course it does not have any detail about this port, which is apparently the unloader valve actuation port. The other diagram also shows a centrifugal unloader. I think I'm just going to have to run this up to pressure to see if it unloads
 

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Looks to me like it's got hydraulic intake unloaders. Common on pressure lubricated pumps.

Pump won't load until oil pressure builds - at which point the intake valves will be released and will function normally. You should be able to spin it over by hand with only belt and piston-ring resistance if this is the case.

Listen during startup:

https://youtu.be/GC8RKMTH678?t=109

1:50
 
Looks like I found some good photos of one like mine. It looks like this was equipped with a piloted unloader and that's what attaches to the mystery port on the head. I need to read up on how these operate, but I'm assuming it is normally attached to one of the extra tank pressure ports underneath the pressure switch and then just controls that unloader shuttle valve based on its pilot setting. I think normally these are used for continuous running (right?), but I want intermittent operation like a basic shop compressor so I need to figure out how to do that with this unloader style head. I think the pilot valve pressurizes the unloader port when its max set pressure is attained, whereas a regular pressure switch with an unloader is just a Schrader style vent valve. I don't think I can use a pilot valve like it had because if the pilot is set lower than the pressure switch the compressor will never shut off, and if the pilot is set higher than the pressure switch it will never unload. I could use a solenoid valve between the tank and unloader port in the head and just open the valve when ever the pressure switch opens- is that the best solution?
 

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I'm not positive on the operation of hydraulic unloaders, but pneumatic unloaders are usually configured pressure-unload, atmosphere-load. Meaning the pilot valve applies tank pressure to the unloader head to unload the pump, then vents pressure from it to load it again.

If you do not want continuous run operation, simply leave the pneumatic unloader port disconnected. The remaining hydraulic unloader will allow the compressor to start before loading the pump if it is functioning correctly.

These are often referred to as 'dual-control' pumps, in the sense that opening or closing a control valve supplying the pilot unloader valve will switch between continuous run and start-stop operation, provided the valve and pressure switch set-points are configured correctly.
 
Thanks, good to know. So if I run it up to its pressure switch controlled shut off pressure and the motor stops I'm thinking that I should hear pressure being relieved through the line under the air filter mount and out the air filter
 








 
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