air dryers for 7hp 80 gal. air compressor?

I AM SO SICK of the stupid air line filters leaking and they don't stop half of the water from &%&%& plugging the sandblaster anyway!!!

thx in advance

I have a 4 stage plan to fix it on the cheap.

Step 1 - I got an old propane 40# cylinder and emptied it out, blew it out, then painted it inside and out. Got a 4way 3/4" connection and put it on to the tank. Mounted the tank upside down (4way on the bottom). I added a 3/8" elbow with a 12" stub on it going up into the center of the tank. That's the air out. The air in just blows into the 4 way. The lowest part of the 4 way is a ball valve. This is on my line used for painting and blasting. It's about 55' of line from the compressor and works pretty good. Other parts of the system still had issues.

Step 2 - Added an extra 80 gal tank. Was given an old industrial well pressure bladder tank. Cut holes in the top for air in and air out. The in has a 3/4" elbow to a 12" stub that directs the air to the side of the tank. Hopefully, it swirls the air across the tank, cools it, expands it and drops out the moisture. The air out is a 3/4" coupler to a 10" stub that is in the dead center of the tank. Bottom of the tank has a ball valve for draining water. (Yes, the rubber bladder was cut so water can get out!)

On the left is the main 7 hp compressor with a black 60 gal tank. The blue tank is in the middle and estimated at 80 gal. On the right is a 3 hp 110v compressor that had it's tank rust out. It is mounted without a tank, bolted to the table. It's air goes to the blue tank via a T. It's only used when lots of air is needed, typically for sand blasting.

Step 3 - build a cooler separator to put on the output from the compressor, before it dumps into the tank. 2 pieces of 18" long 2" pipe, 1 T, 3 caps 2", two 3/8" couplers, 1 3/8" elbow, 1 3/8" MPT to 3/8 compression fitting and 1 6" 3/8" stub. The T is in the middle and is the air in port. The air comes in thru the cap which was drilled and had a fitting welded to it. See picture of the modified T. The air goes in and down to the bottom where it expands, cools and dumps moisture. There is a cap on the bottom with a drilled hole for a 3/8" pipe with ball valve for water out. The air goes up and out the top then into the air compressors original storage tank. Hopefully a bit cooler and dryer. This set up should work well, but will heat fast with a 1 stage compressor.

Step 4 - add active cooling with a radiator and fan after the compressor and before the Step 3 water separator. A/C condensor with a fan wired into the compressors pressure switch.

In my quest for cheap dry air, I am done with steps 1 and 2. The gizmo for step 3 is made and needs to be mounted to the tank and plumbed in. The improvement from adding the extra tank was tremendous and that has taken away much of my motivation for steps 3 and 4.

jb

There are three basic types of commercial air driers; refrigerated, dessicant and deliquesent. They are all plumbed into the distribution line. Some require electricity and some do not. A "filter" is not a drier in any conventional sense, despite marketing claims to the contrary. A refrigerated drier uses a conventional refrigerator circuit to chill the passing air and force moisture to be condensed, collected and then removed from the system. The dessicant style uses a salt-type of chemical that removes moisture by chemical action. The chemical gets consumed in the process and needs to be replaced periodically. The deliquescent type uses a chemical also but it doesn't get consumed in the process. That chemical gets "regenerated" periodically by heating (usually by electricity) to remove the collected moisture, which is expelled from the system during the regeneration process. I don't have current cost estimates for these type of driers but you can probably check out typical costs on-line. The dessicant would be the cheapest, with the lowest performance and require periodic maintenance. The deliquescent will be expensive and have the best performance. It will usually not be necessary for home shops unless there is a specific need for extremely low air dewpoints (which is unlikely). The refrigerated type is not exactly cheap but works well, requires essentially no maintenance (it's basically a refrigerator) and should be satisfactory for all "normal" uses of compressed air. It's certainly the type I would choose should I want to add a dedicated drier to my own system.

You don't indicate whether your compressor is single or two stage. Single stage compressors will always require more attention to moisture removal, by their operational nature. Air-cooled aftercoolers can be used to advantage on either single or two stage machines and are sometimes provided as OEM options for the better two stage units. Those are nothing more than a radiator that the compressed air passes through. They utilize atmospheric air blowing across the radiator as the cooling medium. There are water-cooled aftercoolers also. They are more efficient than the air cooled ones but require a continuous supply of cooling water. They are generally not used in a home shop for that reason.

Baiscally, anything you can cobble together that cools the air, collects the condensed moisture and provides a convenient means of removing the resulting condensate from the system will work, at least to some limited extent. Even long runs of metallic piping upstream of any pressure regulator can be utilized to advantage. The most positive result, however, is obtained with a dedicated commercial air drier unit.

Rod