Compressor to Tank connection

Boswell

Boswell

Hobby Machinist since 2010
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Sometime back I replaced the tank on my compressor and in existing copper pipe would no longer work. At the time I replaced it with a 24" hydraulic hose that had NTP Female NPT on one end and something else on the other that would "spin" to allow me to tighten the connection. This mostly worked but the end that "spun" was not really correct and over time it leaked and the leak is now bad enough that I want to replace it. Here is where I could use some HELP. I mostly understand basic NPT fittings and in my case the compressor has 3/4" FNPT and the tank is 3/4" FNPT. I also have a nice hose with 3/4" MNPT threads on both ends. What is the fitting type that I need that "spin" so I can install the hose? This has to be common and easy, right? but l just can't seem to find the right part to search for. It would need to be something that will go on the MNPT threads on the hose and the FNPT threads on the tank and be able to be tightened without spinning the hose.
:bang head:
 
When I installed a hydraulic hose on my own compressor, the crimped-on hose ends were actually some kind of tapered fitting. There were also a couple of matching tapered fittings that went to NPT. As best I can recall, at least one of the tapered fitting ends on the hose was free spinning. I got my hose at Tractor Supply, but I'm pretty sure hydraulic hoses and fitting hoses are standardized, so it shouldn't matter where you go.
 
What you need is called a Union. They are typically FNPT on both ends but a close nipple will change it to MNPT on one end.
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OK that will work. seems bulky but if that is the best option, then easy to install

Thanks
 
You cold also use copper pipe and compression fittings, I often use Swagelok or similar fittings. They can be taken apart and resealed, and have very high pressure ratings. There should also be a check valve that screws into the tank in the line from the compressor, I would not use rubber/hose due to the heat. They also make 3/4" NPT Male x 3/4" NPT Female Swivel Adapter in various prices ranges, this one is only $3.55 plus shipping. You would need to use a coupler on one end.

3/4" NPT Male x 3/4" NPT Female Swivel Straight 1404-12-12 Adapter | NPT Female Swivel to NPT Male - Straight | NPT to NPT | Hydraulic Adapters & Fittings | Hydraulics | www.surpluscenter.com

3/4 NPT Male x 3/4 NPT Female Swivel Straight 1404-12-12 Adapter, NPT Female Swivel to NPT Male - Straight, 3/4 NPTM x 3/4 NPTF SWIVEL, 3/4&quot1404-12-12,
www.surpluscenter.com

OR this which is a female to female.

NPT Female to NPT Female - Swivel Union | NPT to NPT | Hydraulic Adapters & Fittings | Hydraulics | www.surpluscenter.com

NPT Female to NPT Female - Swivel Union,NPT to NPT,Hydraulic Adapters & Fittings,Hydraulics, 1&quot NPT Female x 1&quot NPT Female Swivel
www.surpluscenter.com
 
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Just take what you want to replace to Parker Hose. Buy the components from them, and they'll swage a new one up for you. Worst case is they'll order the parts from the mothership, but they can do it right.
 
Choose material wisely. You likely have an aluminum head. there will be moisture in the air coming out of the compressor, you do not want rust or galvanic corrosion from dissimilar metals to eat away the threads over time.

As mentioned above I would stay away from rubber hose unless it is specifically rated for the very high temps coming out of the head.
 
Thanks all, agree with the Temperature concern and the galvanic risk. Still deciding how best to proceed. Might just figure out what I need to bend an flair copper pipe. After all, more tools is a good thing, right?
 
Bending and flaring is the easy part.
 
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