can compressor unloader valve be too small?

[gkring]

Been using the same 60 gallon cambell hausefield twin cylinder compressor for years. When it shuts off I had maybe 1 or 2 seconds of the hiss of the unloader valve. I recently added a hayden trannny cooler as an aftercooler between the compressor and tank check valve. Now when it cycles the unloader is open for at least 10 seconds. Enough to make others think it is stuck. It does consistently shut off. A decent volume of extra air was added with the aftercooler, but not that much. Is it just too much for the stock unloader valve?

P.S.--did a search and read a couple 30 page compressor mod and aftercooler threads. Anything relevant to unloader valve just dealt with stuck ones. Nothing about one running too long.

 

[The Cobbler]

the more air volume you have to unload, the longer it will take . those orifices on the unloaders are relatively small . nothing to worry about, as long as it's unloaded before the compressor kicks in again LOL

 

[azchrisf]

Mine does the same thing on a DeWalt two stage. Gotta remember you used to have a short length of pipe for the air to unload, now you have an entire transmission cooler that needs to be unloaded. They didn't design them for use with aftercoolers butNo issue it just takes longer. As cobbler said as Long as it is done unloading by the time it kicks in again yeah you have no problem

 

[84prerunner]

thats too be expected, its just draining the air out of the cooler. You could replumb it so the check valve and unloader are before the cooler that way the unloader doesnt haveto drain the cooler every time.

 

[skulldrinker]

I have for an after cooler 50' of copper tubing buried in the ground outside before entering the tank. I too have long hissy fits. That is normal.

Sent from my SM-N960U using Tapatalk

 

[toolmiser]

I have a 30 yr old compressor that hisses for way to long after shutoff (I believe its a sanborn three horse). I guess that the valve is shot, is that something I need to get from the original manufacturer, or is there better places?

Thanks

 

[gkring]

Cool, thanks.
Knew what was causing it and figured no harm, just slightly annoying. Love the cool air going to the tank now. Just was wondering it I needed or could resize the unloader. I will just live with it.

 

[metlmunchr]

I have a 30 yr old compressor that hisses for way to long after shutoff (I believe its a sanborn three horse). I guess that the valve is shot, is that something I need to get from the original manufacturer, or is there better places?

Thanks

If air continues to come out of the relief port on the pressure switch then the check valve at the tank is likely leaking air back from the tank.

Most of these valves on home shop type compressors have a male pipe thread that screws into the tank and a compression fitting thread on the inlet end. There are several different ones available on Amazon by searching "air compressor check valve". Just have to match up the threads with what you've got now. Some compressors have the pressure relief line tied into the valve itself while others will have the relief line piped into the cylinder head of the compressor itself. Both types of check valves are available, with the ones having provision for the relief line having a small tapped hole in the side of the valve body.

FWIW, these check valves are usually the first thing to fail on a compressor that gets much use. I've got a little 3hp craftsman that I bought in 78 that's been used quite a bit. I've replaced the head gasket once, but the check valve has been replaced at least 4 times. I've bought the replacements from various sources, and unfortunately, one is just as crappy as the other.

 

[toolmiser]

If air continues to come out of the relief port on the pressure switch then the check valve at the tank is likely leaking air back from the tank.

Most of these valves on home shop type compressors have a male pipe thread that screws into the tank and a compression fitting thread on the inlet end. There are several different ones available on Amazon by searching "air compressor check valve". Just have to match up the threads with what you've got now. Some compressors have the pressure relief line tied into the valve itself while others will have the relief line piped into the cylinder head of the compressor itself. Both types of check valves are available, with the ones having provision for the relief line having a small tapped hole in the side of the valve body.

FWIW, these check valves are usually the first thing to fail on a compressor that gets much use. I've got a little 3hp craftsman that I bought in 78 that's been used quite a bit. I've replaced the head gasket once, but the check valve has been replaced at least 4 times. I've bought the replacements from various sources, and unfortunately, one is just as crappy as the other.

Thanks for the info, didn't know myself, and didn't know who to ask.

 

[Bigblockyeti]

Sounds like everything is fine, in fact having more volume after the pump and before the check valve gives the motor additional time to gain pump speed before the full load is placed on the pump and motor.