Thread size on compressor pump

[blair683]

So I got a killer deal on an off brand 3.7hp compressor pump and electric motor. Both were still new in the box. I retro fitted them to a 60 gallon Craftsman tank that used to have an oil free pump on it. i got everything hooked up and running. I just need to get the main copper line from the pump to the tank. I also need to plug the other small threaded hole beside the air supply hold on the pump. Does anyone know what the thread size is for these holes? I am going to go tomorrow and try to find the line and plug and would like to know the thread size. Below is a link to the pump motor. Any information is greatly appreciated.

https://www.aircompressorsdirect.co...MIztOS1uCb1gIViCaGCh3k1QXdEAQYASABEgIedvD_BwE

 

[RocketScott]

I would say they are both NPT (National Pipe Thread).

You should be able to approximate what size by looking at it.

Is the small hole for an unloader? You might not want to plug that. Usually there is a line off the regulator to unload the head once it stops pumping. There will need to be a check valve on the tank connection for this to work.

Another option is to use an air genie unloader.

 

[The Cobbler]

...

You might not want to plug that. Usually there is a line off the regulator to unload the head once it stops pumping. There will need to be a check valve on the tank connection for this to work.

or the line is off the check valve, often 1/4" od copper or aluminum with compression fittings



the air supply is probably 3/8 or 1/2 npt
the unloader port probably 1/8 or 1/4 .

 

[blair683]

I seen a new compressor at tractor supply with the same pump and the unloader hole was plugged. Normally the unloader hole would go to the shut off valve that is connected to the off switch. But like my tank the one at tractor supple had a "T" on the tank that went to the shutoff valve.

 

[The Cobbler]

the unloader needs to go to the pump side of the check valve
that T you are seeing on the tank is a check valve

 

[blair683]

https://www.tractorsupply.com/tsc/p...belt-drive-air-compressor-60-gal?cm_vc=-10005
This compressor has the same pump as me. I was looking at it at tractor supply and it has a plug screwed into the "unloader hole". Is this a bad idea then? As you can see in the pic that there is no line beside the supply line on the pump.

 

[The Cobbler]

it's fine to be blocked off as long as you have an unloader piped in somewhere between the check valve & the pump.
you need to relieve the pressure on the pump after it shuts down so when it starts up it isn't starting against tank pressure .

 

[blair683]

I think I may. Everything on my tank is still hooked up as it was with the oiless motor. I just took the air supply line off of the oiless pump which is a different thread then the new pump.

 

[The Cobbler]

so it should work fine for you, block off the unloader port in the new compressor and you're good to go .. maybe LOL

 

[blair683]

I for sure have an unloader valve. I just found this image of one. I wasn't sure that was called an unloader valve I also learned what it does, lol! Sorry for my ignorance but I never messed with an air compressor other than using them.

 

[The Cobbler]

no worry ' learning new things is good. and resurrecting things from dead are even better