Air line auto drain

[Kevin Cackler]

I recently bought and installed this moisture filter system - https://www.ebay.com/itm/Arrow-Pneum...53.m2749.l2649

The filters all have drains installed on the bowls. The "manual" lists them as overnight drains. For the life of me, I cannot figure out how they work. I cannot figure out a way to manually trigger the drain action, and the only way I've figured out how to activate the auto drain feature is to shut off the air with the ball valve, then empty the remaining air in the lines. Once the air lines are empty, the drains open up and water drips out. Is this really how this type of system is supposed to operate? We typically just turn off the power to the compressor overnight and I'm worried that we're not going to be able to remember to drain the air lines on top of that.

[Jim Becker]

I use an IR Auto Drain and have since I first bought my 60 gallon compressor. It's a great thing and I honestly NEVER drain my compressor purposefully. (It does go down on it's own when it's off when I travel from small leaks in the system) No moisture issues ever that I've been able to perceive.

[Chris Parks]

I have an auto drain on my compressor and we recently bought a new screw compressor which has an auto drain and I wouldn't be without one. What I recently learned was to check the operation of the auto drain, my son's workshop had to replace the motor on their screw compressor when the reservoir filled up with water due to the auto drain valve operation failing and the motor having to work constantly because there was no air reserve. The motor cost $10,000 BTW.

[Mike Heidrick]

I use the timed auto drains from ebay. They are $20ish dollars.

[Charles Lent]

I've had three auto drains on my shop air compressor tank and all three have failed. Two years ago I gave up on them and just piped the drain port on my compressor tank to a small tank made from 3" pipe and reducer fittings on both ends. There is a ball valve on the outlet end of this tank and pipe running through the wall of my compressor shed. The outside end is pointed down toward the ground. Now, every few months, I open this ball valve and vent the accumulated condensate under pressure to the outdoors. It works great and there is never any condensate build-up in my compressor tank. If this small tank ever develops a pin hole, I can easily replace it at a minimal expense, but it will likely last longer than me because it's wall thickness is about 1/4" or about 4X the thickness of my 80 gal air compressor tank.

Cooling the heated air from the output of your compressor before it enters the tank is the best way to avoid moisture in your shop air lines. When the air cools it releases the moisture. When it cools in the tank it releases the moisture there. If warm compressed air can enter your shop air lines, it will cool there and give up it's moisture, resulting in water in your shop air lines.

A good way to have relatively dry air for your shop is to add a cooling coil to the output line of the air compressor itself, so the air is cooled before it enters the tank. Fins on an air line that forms a couple of circles before reaching the tank entrance and locating these circles in the air stream of the fan in the pulley of the air compressor, or adding a small electric fan that runs whenever the air compressor runs to blow across these coils, will remove the heat from them, so the air entering the tank is about at ambient (surrounding air) temperature. When the compressed air cools, the moisture in this air becomes condensate and falls to the bottom of the air tank, keeping the volume of air in your tank much cooler and lower in moisture content.

For my smaller 20 gal 2 hp compressor I used a small automotive air conditioner coil mounted so the fan in the air compressor pulley pulls air through it. For my 5 hp 80 gal compressor I used finned pipe formed in two loops as the cooling coil because it is 5/8 tubing and I did not find an air conditioner coil with that large of piping, however a large transmission cooling coil, like maybe one for a large truck might have been a good alternative. You don't want to restrict the flow of air from the compressor with under size piping.

After modifying my air compressors by adding cooling coils between the compressor outlet and the entrance to the tank I no longer ever have any condensate collecting in my shop air lines or filter/separators. I recently acquired a refrigerated air drier and I now use it as well, whenever spray painting or sand blasting, as a safeguard to further dry the air, but I only use it for these high volume uses and it has not ever been needed for keeping my shop air dry.

Charley

[Chris Parks]

Obtain an old fridge and put a small portable air tank inside it and run the air through that by cutting two holes in the fridge walls. Drain tank when you think of it.

[Joe Jensen]

Obtain an old fridge and put a small portable air tank inside it and run the air through that by cutting two holes in the fridge walls. Drain tank when you think of it.

That sounds like a great idea, thanks. I think I would put a coil of copper tubing inside above the tank.