Thread: Make a copper coil for air compressor line?

Originally Posted by Dengue

Hi, I want to to put a long 1/2" copper line in my air compressor line for water capture. Normally these are run in long lengths across and /or up and down a workshop wall, but I don't have room.

I am thinking of making a coil of 1/2" copper tube available in 6 m lengths, the coil to be about 150 -200 mm diameter. It will be mounted on a backing board. Could be made portable too

Can anyone please tell me if this is possible, and the best way to do it?

Rather than go that way, it is easier and cheaper to use a junk car airconditioner evaporator (the thing in front of the radiator) and connect a water trap to that.

You can use compression fittings or brase/silver solder it together.

You sometimes see people give them away on Gumtree.

Cheers

Rob

Hi Rob,

Originally Posted by nearnexus

car airconditioner evaporator (the thing in front of the radiator)

I think you'll find thats the condenser
But a great idea. Wouldnt getting them level be more of an issue though?

Stuart

Originally Posted by Stustoys

Hi Rob,


I think you'll find thats the condenser
But a great idea. Wouldnt getting them level be more of an issue though?

Stuart

Meant to say condenser, was thinking condenser. Typed evaporator LOL.

Never tried it, but people use them quite successfully.

The air flow would tend to push the condensation through the small tube.

Rob

Originally Posted by nearnexus

was thinking condenser. Typed evaporator LOL.

So I'm not the only one then

Thinking about it a little more, as best I know its not an issue in a car so I'm guessing it wont matter in an airline either.

Now where is the best place for it? after the reg before the water trap?

As far as the OPs copper pipe goes. The pipe you'll be buying would be coiled already. If you bought the straight length(can you even get it in 1/2"?) you'd have to anneal it first.

Stuart

Originally Posted by Stustoys

So I'm not the only one then

Thinking about it a little more, as best I know its not an issue in a car so I'm guessing it wont matter in an airline either.

Now where is the best place for it? after the reg before the water trap?

As far as the OPs copper pipe goes. The pipe you'll be buying would be coiled already. If you bought the straight length(can you even get it in 1/2"?) you'd have to anneal it first.

Stuart

Definitely needs to be before the water trap, which definitely needs to be before the regulator.

You don't want moist air going through the regulator.

It's particularly bad news with those cheap die cast Asian regulators, which soon corrode up.

Rob

Originally Posted by Stustoys

So I'm not the only one then

Thinking about it a little more, as best I know its not an issue in a car so I'm guessing it wont matter in an airline either.

Now where is the best place for it? after the reg before the water trap?

As far as the OPs copper pipe goes. The pipe you'll be buying would be coiled already. If you bought the straight length(can you even get it in 1/2"?) you'd have to anneal it first.

Stuart

either evap or condenser will do but the tubing size in car coils will most likely be too small in dia...one from a truck maybe ok

small tubing will put too much restriction on airflow..the compressed air!

most evaporator coils from a cold room would be suitable as the tubing larger dia

There are/were a few discussions on this subject, and the one I liked in particular was the gal pipe solution...here...

Something to keep in mind is the smaller the tube the more water will stay in suspension due to the air speed rising as the tube size falls. Minimum size for a copper coil would be 3/4" if you want to keep the air speed down and allow the copper to work as it should. Putting the coil inside a fridge will work really well or install it in a smallish drum and fill that with water. Drains installed to suit of course.

Ok...high school science moment... It's been a while! Go easy on me!

I think part of the point to go to a larger diameter pipe than the delivery tube is you want the compressed air to be able to expand in it. An expanding gas cools by nature so it aids in producing condensation. I think....

When it is sitting idle, the pressure is all equal, when you are drawing compressed air, it goes from a small delivery tube and expands into the condenser tube and cools slightly. By insulating the condenser tube you improve this effect.

Now saying all that, my condenser tube is a 1/2inch copper riser about 1500mm long and is right next to the compressor, then to shop lines- to a reg and commercial water trap, then to a long retractable hose. I have never had a drop of water make it to the commercial water trap in two years and it's very humid here. I get a lot of water in the condenser, more in summer. If I was in FN Queensland, I would probably go bigger.

My riser is fixed to a timber batten on brick wall to help insulate it.

Now, I hope that was not a 'skool' moment!

Originally Posted by Ben Dono

I think part of the point to go to a larger diameter pipe than the delivery tube is you want the compressed air to be able to expand in it. An expanding gas cools by nature so it aids in producing condensation. I think....

When it is sitting idle, the pressure is all equal, when you are drawing compressed air, it goes from a small delivery tube and expands into the condenser tube and cools slightly. By insulating the condenser tube you improve this effect.

Now saying all that, my condenser tube is a 1/2inch copper riser about 1500mm long and is right next to the compressor, then to shop lines- to a reg and commercial water trap, then to a long retractable hose. I have never had a drop of water make it to the commercial water trap in two years and it's very humid here. I get a lot of water in the condenser, more in summer. If I was in FN Queensland, I would probably go bigger.

My riser is fixed to a timber batten on brick wall to help insulate it.

Now, I hope that was not a 'skool' moment!

Yes true,the air does cool by expansion but the air from a compressor is not in large enough volumes to allow any real benefit in cooling...this generally only works thru small orifices and high air volumes are important to make these work effectively. ...but are also inefficient

no, you dont insulate the pipe...the air leaving the compressor is superheated during compression from compressor....you need to cool this so that moisture condenses out of the air stream
insulating it will will just allow it to remain hot preventing moisture from condensing out...refrigerated air driers do this by cooling the air.

The more surface area one has allows for greater cooling.

My comment on the pipe size was for the whole system. Most hobbyists do not pull the air required to get water in proper suspension in large amounts until they use high demand air tools. I have mine piped in 3/4" and from the compressor to the first separator it has about 10 metres of copper and 7 of that is vertical outside the workshop. The compressor has an auto drain on it so I always reckoned I had all bases covered. I bought a die grinder for a particular job and when we started using it the water came through the air line like a waterfall, you could see it entering the separator. It only happens with that tool and if I was using it a lot I would duplicate the line from the compressor. When I did the installation the guy from Pulfords warned me it was only marginal in this regard and I dismissed his advise as I was sure he was wrong.

Good point Eskimo! I should have explained it better. I ment insulate it from heat. My riser is on a north facing brick wall which gets hot in summer. I insulate the riser from the hot wall with a timber batten.

Originally Posted by Ben Dono

Good point Eskimo! I should have explained it better. I ment insulate it from heat. My riser is on a north facing brick wall which gets hot in summer. I insulate the riser from the hot wall with a timber batten.

Instead of insulating it would be better to shade it so the air around it can still cool the pipe.

Originally Posted by BobL

Instead of insulating it would be better to shade it so the air around it can still cool the pipe.

I think that is what he means Bob..ie keep it away from additional heat source to increase efficiency...
but one needs to make sure it has air movement around the pipe else the static air can heat up and decrease effciency