Dry Air!

[binfordw]

Hi,

Been awhile since I posted, I've been up and running with my plasma table for some time now- thanks to alot of help from here.

I still seem to be battling moisture problems however.

I currently use a Motorguard paper element filter- followed by a fairly large regenerative (manually) dessicant filter- it holds 1.75lbs of dessicant. I've been very busy lately, working the table to death. I seem to be flying through paper filters, and having to re-dry dessicant often.


Would a refrigerant type dryer provide similar air quality with lower maintenance? I'm leery of buying the cheap one Harbor freight sells, I wouldnt mind buying a well made one but would like to make sure it will solve all of my air quality issues.


Would using some sort of "trap", such as a plumbed elbow- be very helpful? I get ALOT of H20 at the inlet to my paper filter, something to help cut down on that could extend my media's life.


Any thoughts or suggestions would be greatly appreciated,

Thanks,


Ben W

[sbi1406]

Go to your local auto paint store and get one of their toilet paper filters.

Use this first in the line, single ply works great, a cheap way to grab the bulk of the liquid flowing down the pipe, and the paper is cheap compared to elements filters.

[neilw20]

You really need to remove the water before the air is compressed.
You could try ducting the inlet air through an old fridge!!

Expect a flood. I've seen a fridge sitting a big tray. hahah
You will soon see how much water even that will produce.

You really need to spend the money to get the results.

[Shefron]

Originally Posted by binfordw Would a refrigerant type dryer provide similar air quality with lower maintenance? I'm leery of buying the cheap one Harbor freight sells, I wouldnt mind buying a well made one but would like to make sure it will solve all of my air quality issues.

The HF refrig dryer actually gets stellar reviews from people.

[BobWarfield]

You can remove a fair amount of moisture without too much cost or effort with an aftercooler:

Aftercooling a Compressor to Cut Down on Moisture « CNCCookbook

It's not as good as a refrigerated cooler, but they sure do help. One of those with the aforementioned toilet paper filter will remove a lot.

Cheers,

BW

[WSS]

Originally Posted by Shefron The HF refrig dryer actually gets stellar reviews from people.

I bought my HF dryer from craigslist for 150 bucks. It was used to do some testing with a laser and had (I was told) about 5hrs on it. I have put hundreds of hours on it with nary a problem, cut today for nearly 10 hours. The "auto" drain only drains when the air pressure drops to zero though.

I would by another without hesitation.

WSS

[WCIS]

neilw20 is right. For best results spend some money.

However, I have seen a couple home made refrigerated dryers where an old refrigerator was used. A 25 foot coil of copper tubing was sort of srtetched out into a spring shape inside the fridge supported with 2x2 lumber and wire ties. Each end of the tubing was shot through the side of the sheet metal to the outside and the holes sealed. An auto drain trap was installed at the bottom which was also the inlet. The top connection went to the shop supply line. There was still plenty of room for beer, sandwiches, etc. What every shop really needs.

Note this is different than what neilw20 suggests in that this is on the high side of the compressor. If you can get this between the compressor and tank you can keep a great deal of water out of your tank. Be damn sure you have a working relief valve on or near the tank should you run long enough to get a mass of cold air in the tank then shut it down for a while. As the cold air warms it will expand exerting more pressure on the tank. An 80 gallon tank explosion can level a two car garage.

[courtiron]

The best dryers are desiccant type. The will dry air to a -80 degree dew point. Obvious the best that you attain with a refrigerated system is about 35 degrees, any colder and the water freezes in the cooling loop.
If you use a dedicated air drop for the plasma cutter, you dont need a huge dryer.

I use this for my plama cutter...Inline Desiccant Dryer/Filter

or for my high pressure (3500 psi) air compressor

http://images.harborfreight.com/manu...7999/97686.pdf
although it appears to be no longer stocked, if you can find one they are great.
need to get my refills somewhere else, maybe here

Activated Alumina Desiccant - 1/8-inch 55 lb Bag | Compressed Air Desiccant


see also:
Sharpe Dryaire Desiccant System, Model# 6760 | Dryers | Northern Tool + Equipment


The Northern Tool system uses a pre filter, a coalescing filter and the desiccant filter.
The only point that I would disagree with regarding the NT system is the location of the pressure regulator... and the price...

The amount of moisture that air can hold falls with decreasing temperature. The air leaving the regulator is cooled by expansion. If you have the choice, locating the regulator ahead of the coalescing filter will mechanically remove moisture, reducing the load on the desiccant filter, however, if you run near system pressure on your plasma cutter, the effect of the PRV location is lessened.

paul

[flyinwilly]

I am using a setup similar to what you described. I have a Motorguard prefilter which feeds a Domnick Hunter regenerative dessicant dryer and a coallescing filter on the output. I use this setup not only for the plasma but also the air tools including a sandblaster, spray guns, etc. I haven't had a drop of water in the final water traps in a very long time. The only difference from what you described is that my dryer is automatic, it cycles every minute, and it uses 6 lbs. of dessicant (activated alumina). Maybe your dryer is too small for your application.

One other big change that I did make is add a second compressor. My older unit is a 40 gal, 3 cyl, 5 HP and it would get really hot. I had to drain the tank constantly although no moistue got into the lines. I added a 60 gal, 3cyl, 5hp unit and plumbed them together. I get a lot more air and the pumps stay much cooler and don't generate as much fluid in the tank. I don't have to change the prefilter as often either.

Good luck with your setup.

Willy

[courtiron]

Flyinwilly:

I use the filtered air in my air tools, the desiccant system is only for my plasma cutter... under my limited usage I get 3 months out of the small inline filters. My system has a number of water traps before it gets anywhere near my dryer and plasma system.

Is your coalescing filter down stream of your desiccant dryer?
It should be upstream of the desiccant system. You can put a post filter inline to trap any alumina dust that may exit your dryer, especially if you repack the system.

If your system, is large enough, and it certainly sounds that way, you have the best system. Supplying clean, dry, oil-free air is the ultimate air supply for all tools and uses. Good deal!

paul

[flyinwilly]

I bought the dryer used and it only came with the one downstream filter so I just left it there and added the motorguard as the prefilter. I was going to buy the correct Domnick Hunter filter but it would cost more than I paid for the dryer. I use the ownstream filter as my indicator when to change the dessicant. If I get any oil, I change the medium. It will usully have a slight yellow tint at that point. Maybe I'll reverse them and try it that way. Thanks for the info.

Willy