Air compressor line getting hot.

krm

Member
I have a small compressor that when running the air line from the compressor to the tank is getting very hot. Does anyone know what the reason for this and what to do to fix it?
 
Probably normal. compression causes heat. Same reason you get heat out of the condenser coil on air conditioner or refrigerator
 
Compression caused heat be it air of hyd fluid it causes heat. But on the other side of thing if you decompress air at a fast rate it can/will cause things to get cold and at times very cold to the point you can cause things to frost up and if your putting the air in say your hand you can cause frost bite.

Just like on the head of that compressor you could crack and egg and put it on the head and have a fried egg. That is why if you look at the compressor it has a fan that helps cool the compressor as it runs
 
The compressor head has cooling fins to cool it, and you are feeling the surface temp of the fins rather than internal temp. Many compressors have cooling fins on the line you are referring to also.
Loren
 

This was covered in high school science or physics class. It is why intercoolers are used on some turbo engines. It is how air conditioners and heat pumps work. It is how gasses are separated for argon, CO2, oxygen etc.
https://en.m.wikipedia.org/wiki/Gas_laws
 
The compressor it self has cooling fin and if you touch it you feel the top of the fins not to head it self. Just like a lawn mower engine or a motorcycle engine they have fins and are cool by air movement
 
NOW, if that worrys you there is a fix. Go to a scrap yard, plumbing supply, house with baseboard heat, etc. Get hold of of few pieces of the copper tubing with those fins on them . Soilder up yourself a cooler. You see these on some really big compressos on the pump out put. At the end of that cooler put a drip pipe with a little drain valve. Surprise how much water will come out. Some of this was covered a couple of months ago on here. You can make a big cooler or run the line through an old refrigerator. Look on ytube how to do.
 
Usually it's not a problem except when painting. Expanding air leaving a spray gun instantly cools and water droplets form. The fix is to cool the air in the line and trap the water prior to the spray gun. In a home shop usually 30 ft of pipe ending with a water trap is good enough.
 
It is normal for the line to get hot and in some cases the air leaving the compressor can be over 500 degrees. If you are into matchless fire starting a fire piston works because of this.
steve
 

It is normal for the line to get hot, but, it won't hurt to check to be sure that it is tight. They can loosen up with the vibration then they get even hotter.
 
Some of that fin tube copper pipe has REALLY thin walled tubing. I don't know if it would handle the pressure.
 
I put together a small compressor a few years ago to air up small tires. Bicycle, lawn mower etc. The line from the compressor to the tank is copper. Since it never moved, I never noticed that the line got hot. last week, I took it to my step daughters house to air up a tire with a slow leak so she could take it to a tire shop to get it fixed. When I went to pick it up to put in back in my truck my forearm touched the copper line. It branded me pretty good. Now I know.
 
With a little more compression (and heat) that's how a diesel lights the fuel when it is injected into the cylinder.
 
The last time I had a compressor did that the compressor was defective. It shouldn't be generating that much heat. Not only was it heating the plumbing it was dispensing too much oil into the air which was screwing up the painting work I was doing.
 
(quoted from post at 09:31:52 04/22/17) With a little more compression (and heat) that's how a diesel lights the fuel when it is injected into the cylinder.

Direct injection gassers operate the same now when revved up and under load .
 
Like Stephen said ,a compressor that is letting excessive oil past the piston will ignite the oil vapors under compression just like a Diesel and cause the pressure pipes to the tank to get very hot.Also the air coming out of the tank will have a burnt oil smell.I have seen it a lot on yard spotting tractor that the air compressors get worked very hard.Also seen a few older/worn stationary compressors that also did this,you could even hear then firing in the air tank and the tank be overly hot.
 
It is normal for them to get hot, too hot to touch.

But if this is something you've noticed that wasn't there before, and/or the run time seems longer, the volume is reduced, might be worth looking into.

Some small compressors have a check valve where the line goes into the tank. The valve may be partially blocked with carbon or the spring broken, or something blocking the valve movement. There are also valves in the head. The exhaust valve can be partially blocked with carbon, restricting the air flow.

Also if the motor has been changed, be sure the rotation is correct. The flywheel fan blades should blow air toward the compressor.
 

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