air dryer for compressed air system

jimg · Feb 19, 2009

I really need some sort of water filtration on my compressor and have seen a couple types...dry and refrigerated. Wix makes what looks like the easiest most convenient of the dry types called AquaChek. Filter costs start at $25/ and would need to be changed at least once/yr. Also they recommend a couple in line, one closeish to the compressor and another smaller down line. The other option is to roll my own using a refrigerated system. I see there are some plans on the net for this.

What Id like to know is which way did you go and why. If you rolled your own what did it cost and how effective is it.

ETA: The big question on the 'roll your own' is how to vent the condensed moisture from the compressed air stream. Not sure how to do that.

Scooby074 · Feb 19, 2009

I use 2 coalescing filters and a dessicant filter on my system.One Coalescing filter is just after my compressor. Then comes my dessicant. Last thing is a coalescing filter with my regulator. My system is hooked up with black pipe and this helps alot. My dessicant is about 40' from the compressor, so the air has cooled quite a bit by the time it gets there. This helps the separation of water. All my lines are sloped and i get as much water out of my lines as i get out of the filters.
If you go with dessicants, you can build your own filter out of a large (6" dia.) threaded pipe and end caps. Get the good dessicant from a pneumatic supply, it changes colour when its wet, and its reuseable (dry in oven) .

jimg · Feb 19, 2009

What is a 'coalescing' filter?

A big problem w/ my setup is the water sep is way too close to the tank. I like your idea of angled pipe. Is there a drain trap in your system?

ultrarunner · Feb 19, 2009

I need very dry air to use in conjunction with medical equipment sterilizers...

The most water by volume is removed by the automatic compressor tank drain valve... it has adjustable cycle frequency.

Next the air goes through a refrigerator/dryer which is also automatically drains.

Some of the runs are over 300' with the copper pipe is sloped back to the refrigerator/dryer.

Coalescing Filters are used at the end of all the drops... In a years times each filter will still pick-up a tablespoon or two of moisture,

Finally the units also have a 3M double filter pack that never have any detectable moisture.

Whether manual or automatic, frequent compressor tank draining is the cheapest and most effective.

The old plant actually had large 80 gallon air tanks distributed through out the facility fed from one central compressor. By the time the air travel to the large end of the line tanks the moisture would collect at the tank bottoms and not be a problem. Management wanted to get rid of the tanks and the maintenance draining several tanks throughout the plant and that is the reason for the refrigerator/dryer that runs 24/7

Egon · Feb 19, 2009

What is your budget and how dry must the air be?

When that is decided you could start looking for a system.

jimg · Feb 19, 2009

OK, my interest is really in making something (cold drier) or perhaps buying a dry type unit. As for how dry the air should be I dont know how to answer that exc to say 'dry'.

Hey, this isnt a rocket science thing...I just want to keep my air tools from dieing prematurely and perhaps squirt some paint. The AuqaChek units looked pretty neat, very simple and convenient. The down side is I would have to replaced the filters. If I could come up w/ a cold unit based on 'junk yard' tailings that would be even better. The prob w/ that is figuring out how to automagically vent the condensed moisture from the compressed air stream.

ETA: Oh wait...I think I understand whats wanted. There must be some sort of moisture actuated valve that opens once water reaches a certain point (its sensors). Not sure thought what that would be called. I think it wold do the job though.

Egon · Feb 19, 2009

The AuqaChek units looked pretty neat, very simple and convenient. The down side is I would have to replaced the filter

Using that system for the air tools and adding a desiccant type for the paint squirting may be the easiest way to go. As mentioned the desiccant can be dried.

Scooby074 · Feb 19, 2009

jimg said:
What is a 'coalescing' filter?

A big problem w/ my setup is the water sep is way too close to the tank. I like your idea of angled pipe. Is there a drain trap in your system?

A coalescing type filter is a typical water separator. Its basically a membrane of different pore sizes depending on air volume and how "dry" you want your air. The water falls out of the air as it "squeezes" through the pores. That combines with the air expanding in the bowl creates the drying effect.

Having your filters on the end of a long run will help their efficiency alot due to the cooling of the air. I have drains on both ends of my line.

I wouldnt go with a refrigerated dryer unless you have to. My air is plenty dry for painting and sandblasting. Refrigerated driers work great, but they can be kinda spendy.

DieselPower · Feb 19, 2009

jimg said:
OK, my interest is really in making something (cold drier) or perhaps buying a dry type unit. As for how dry the air should be I dont know how to answer that exc to say 'dry'. Hey, this isnt a rocket science thing...I just want to keep my air tools from dieing prematurely and perhaps squirt some paint. The AuqaChek units looked pretty neat, very simple and convenient. The down side is I would have to replaced the filters. If I could come up w/ a cold unit based on 'junk yard' tailings that would be even better. The prob w/ that is figuring out how to automagically vent the condensed moisture from the compressed air stream.

ETA: Oh wait...I think I understand whats wanted. There must be some sort of moisture actuated valve that opens once water reaches a certain point (its sensors). Not sure thought what that would be called. I think it wold do the job though.

Automatic tank drain valve, is that what your thinking about? There are several manufacturers of automatic drain valves.

If your only trying to remove moisture for air tools then you don't need to get to high speed. A good coalescing type filter and possibly one of the AuqaChek filters is all you would ever need. If you plan on doing any painting then you should get a desiccant filter. If your thinking big for the future then a refrigerated dryer is the way to go. Refrigerated air dryers are by no means cheap. I picked up a nice used one at a industrial auction so keep your eyes out in the auction listings in the paper.

jimg · Feb 20, 2009

To my eyes AquaCheck is a desiccating type drier. Media in the filter captures the moisture and holds it. That said conventional descants can be regenerated by heating whereas AquaCheck can't.

Just off hand I don't think a refrigerated system would be hard to build. (I know theyre very expensive to buy and thats why Im thinking of building.) To me a coil of copper to transmit the compressed air thru a cold coil would be all that was needed. The coil would be fitted w/ a trap and electric purge valve to vent the condensed moisture. Im sure this isnt going to be as efficient as a commercial drier but hey it works for a tiny fraction of the price.

Yes, I guess thats what I was thinking of...an automatic tank drain. Im familiar w/ the pressure actuated types...fitted into the underloader...and that wouldnt be so convenient. If I could get it an electric type would be best. It would sense moisture build up in the trap by completing a circuit when moisture accumulated to a certain level.

Thanx for the description of the coalescing filter...I have one in inline and need to move it farther from the compressor.