I-R 242-5N T30 compressor unloader valve

[Andy FitzGibbon]

I have a 1980s Ingersoll-Rand T30 compressor, with a 242-5N pump and a 5hp single phase motor, that I just put into service. It starts hard, so I thought maybe the unloader valve wasn't working. Turns out, it doesn't have an unloader valve. No centrifugal unit, no needle valve in the pressure switch, and no signs of any plumbing that might have been part of an unloader system.

Were they ever sold this way? It came from a deceased friend's shop, and I expect he bought it new, but it's possible modifications were made somewhere along the line.

Too dark now to get photos of the actual unit, but I've attached an image of one that's basically the same. I can get photos of my machine tomorrow.

Thanks,
Andy

 

[The Cobbler]

hard to imagine it was manufactured with no unloader . it should be easy to plumb one in . it looks like a line to the pressure switch just above & parallel to the base plate

 

[isb cornbinder]

The unloader is a centrifugal unit. When the compressor pump slows down, the valve opens and dumps air from the compressor circuit. ON start-up the unloader is open. The valve slides to closed as the compressor builds speed and the pressure builds.
I installed an external electric pressure switch. This switch has an unloader also.

 

[Andy FitzGibbon]

hard to imagine it was manufactured with no unloader . it should be easy to plumb one in . it looks like a line to the pressure switch just above & parallel to the base plate

I agree. It's just strange that there are no signs it ever had one. No ports in the heads, piping, ect. The photo is not of mine, just a similar one I pulled from the internet.

If anyone here has a T30 and could post a photo of where the unloader line ties in, that would be helpful. The pressure switch was leaking, so I replaced it with one that does have an unloader valve built in. I just need to figure out where to plumb it to.

 

[Andy FitzGibbon]

The unloader is a centrifugal unit. When the compressor pump slows down, the valve opens. ON start-up the unloader is open. The valve slides to closed pressure builds.
I installed an external electric pressure switch. This switch has an unloader also.

My pump does not have a centrifugal unloader. They were made both ways. The pumps without the centrifugal unit seems to be newer.

Too dark to get photos now, but I'll get some tomorrow.

 

[Andy FitzGibbon]

This is my compressor. Built in 1982.





Blanked-out unloader ports in the heads and crankcase cover that were never machined. The line in the last photo is what I'd initially assumed was an unloader, but it's just a crankcase vent.



Check valve and relief valve for the tank feed line.



I spent some time on Google image search, and found a couple T30s of similar vintage that looked to be set up the same way, with no unloader circuit. So I guess maybe they built them this way for a time? Weird, but what do I know... it does always start, even with no unloader valve. The motor has to work pretty hard to get going, but it also seems kinda slow to start with the belts off... I'm going to replace the start capacitors.

I also found photos of a couple newer T30s that had a pressure switch unloader tee'd into the relief valve port on the low pressure side of the intercooler. I guess I'll set mine up that way, unless anyone here has one of these and can tell me what I'm missing, or if there's a better plumbing setup. Most I've seen are tee'd into the high pressure side.

Thanks for the replies,
Andy

 

[isb cornbinder]

The unloader is a centrifugal unit. When the compressor pump slows down, the valve opens and dumps air from the compressor circuit. ON start-up the unloader is open. The valve slides to closed as the compressor builds speed and the pressure builds.
I installed an external electric pressure switch. This switch has an unloader also.

https://www.industrialairpower.com/assets/images/Manuals/2545.pdf?srsltid=AfmBOoqYEMaZtOiIVwbnnKFqIKxn6-m5GYAkv8uRoI6NnVilhtzPlx3k

 

[Andy FitzGibbon]

https://www.industrialairpower.com/assets/images/Manuals/2545.pdf?srsltid=AfmBOoqYEMaZtOiIVwbnnKFqIKxn6-m5GYAkv8uRoI6NnVilhtzPlx3k

Yeah, that manual shows the centrifugal unloader... which, as you can see in my photos, my pump doesn't have any provision for. The boss on the crankcase cover where the valve would go was never machined.

 

[isb cornbinder]

Yeah, that manual shows the centrifugal unloader... which, as you can see in my photos, my pump doesn't have any provision for. The boss on the crankcase cover where the valve would go was never machined.

One more picture. I hope this helps.

 

[Andy FitzGibbon]

One more picture. I hope this helps.

You have something inline in your unloader piping to isolate the low and high pressure cylinders?

 

[isb cornbinder]

You have something inline in your unloader piping to isolate the low and high pressure cylinders?

That is called a check valve.

 

[Shoreline_]

One more picture. I hope this helps.

Wow you have a centrifugal unloader and a pressure switch unloader? Double whammy. You taking that thing on a NASA space mission with all that redundancy? **whistles**

 

[isb cornbinder]

Wow you have a centrifugal unloader and a pressure switch unloader? Double whammy. You taking that thing on a NASA space mission with all that redundancy? **whistles**

I will say "YES" if that fulfills your fantasy.

 

[Andy FitzGibbon]

This is what I ended up doing. Pressure switch unloader for the low pressure side, and a Load Genie check valve unloader for the high pressure side.

I've now found enough photos of early 80s IR compressors with no unloader setup to determine that they did build them that way for a time. Also talked to a couple industrial compressor techs who said the same. Seems like an odd choice. Maybe a cost cutting measure, though it seems like any savings would have been eaten up by motor warranty issues.