Best approach for drying air from air compressor

[Alan Lightstone]

I have a California Air Tools 10020AC compressor (2HP, 5.30 CFM @ 90psi) that I use mainly for blowing off stuff, and supply to my wide belt sander, and occasionally for a staple gun. I don't use other air tools.

Despite having an automatic drain valve on it, it still spits water on occasion. I'm looking for the best way to dry the air from it. I'm sure living in Florida doesn't help.

Is the best approach a desiccant in line filter (with dessicant beads https://www.amazon.com/gp/product/B01L0GEN78/ref=ox_sc_act_title_2?smid=A1VJ396WMF7DIH&psc=1), or something like this PneumaticPlus 3-stage air drying system https://www.amazon.com/gp/product/B016XIWHGM/ref=ox_sc_act_title_3?smid=A158LRHTFH4QLV&psc=1 , or something else?

[Ben Mitchell]

The answer is going to depend a lot on both how much air you use, and what your budget is. In my shop I run the air through a filter/dryer similar to the PneumaticPlus one you linked. That gets the oil and big water and "junk" out of the air. Then I run it through two big desiccant dryers (each holds about a gallon of desiccant granules). That _should_ get all the moisture, but if I'm not really on schedule about recharging the desiccant I'll get water past it in the lines. I'm about to add a "cheap" refrigerant dryer (I found an as-new one like the $400 harbor freight units for $100) right after the tank to trap as much moisture as possible before it even gets to the filter/dryer stuff. That'll prolong the desiccant's life.

If you're using air in any kind of volume (painting / sanding) and you want really dry air, and you're in Florida you've got a task ahead of you. If you're running the occasional air nailer you can get by with a lower volume setup.

[Tom M King]

Best approach is a refrigerated dryer. I bought one capable of 54 cfm off CL for $125, and it's working fine on a 10 hp compressor.

[Alan Lightstone]

The answer is going to depend a lot on both how much air you use, and what your budget is. In my shop I run the air through a filter/dryer similar to the PneumaticPlus one you linked. That gets the oil and big water and "junk" out of the air. Then I run it through two big desiccant dryers (each holds about a gallon of desiccant granules). That _should_ get all the moisture, but if I'm not really on schedule about recharging the desiccant I'll get water past it in the lines. I'm about to add a "cheap" refrigerant dryer (I found an as-new one like the $400 harbor freight units for $100) right after the tank to trap as much moisture as possible before it even gets to the filter/dryer stuff. That'll prolong the desiccant's life.

If you're using air in any kind of volume (painting / sanding) and you want really dry air, and you're in Florida you've got a task ahead of you. If you're running the occasional air nailer you can get by with a lower volume setup.

Really looking for a relatively low cost solution. Unless I happen to get lucky and snag a good value for a refrigerated dryer from CL, I think big desiccant dryers might be the best approach. Any good links for them? The ones I keep finding are small, not nearly the 1 gallon size you were describing.

[Richard Coers]

I had one similar to this in my shop decades ago. https://www.amazon.com/Plews-56-081-Desiccant-Dryer/dp/B00HY4Q1U8/ref=sr_1_22?dchild=1&keywords=EDGE+Industrial+Desiccant+Dryer&qid=1608758881&sr=8-22
For these to work the best, it has to be located as far away from the compressor as possible. It's easier for the water to drop out of the air when it has cooled a bit. After the desiccant filter, I had a "toilet paper" filter. These have a roll of brown paper in them and really grabs the last bit of water. You have to buy their filters, don't expect real toilet paper to work. Besides toilet paper is too precious of a commodity these days anyway.

[Malcolm McLeod]

... the best approach a desiccant in line filter (with dessicant beads https://www.amazon.com/gp/product/B01L0GEN78/ref=ox_sc_act_title_2?smid=A1VJ396WMF7DIH&psc=1), or something like this PneumaticPlus 3-stage air drying system https://www.amazon.com/gp/product/B016XIWHGM/ref=ox_sc_act_title_3?smid=A158LRHTFH4QLV&psc=1 , ...


I had one similar to this in my shop decades ago. https://www.amazon.com/Plews-56-081-Desiccant-Dryer/dp/B00HY4Q1U8/ref=sr_1_22?dchild=1&keywords=EDGE+Industrial+Desiccant+Dryer&qid=1608758881&sr=8-22
For these to work the best, it has to be located as far away from the compressor as possible. It's easier for the water to drop out of the air when it has cooled a bit. After the desiccant filter, I had a "toilet paper" filter. These have a roll of brown paper in them and really grabs the last bit of water. You have to buy their filters, don't expect real toilet paper to work. Besides toilet paper is too precious of a commodity these days anyway.

Mr. Lightstone, the '3-stage' FR (filter regulator) will give you very clean air, and maybe remove any water particulate (already condensed). It will do virtually nothing to reduce the dew point of the air passing thru it. In FL humidity, with a big pressure drop across the regulator, the filter will swamp - quickly!

A refrigerated dryer is the gold standard, if you can swing the cost. Only down side is they typically perform better in continuous operation; not the intermittent use found find in the average home shop.

Failing a screaming deal on a reefer, Mr. Coers is correct on several counts: 1) A desiccant dryer will be your best bet in your (assumed) price range; 2) pre-cool the air if possible (Maybe a 2nd receiver in series with the primary? Even an old car radiator? ::lots of surface area.); 3) locate the dryer as far from the compressor as reasonable; 4) place a FR close to point of use. (Use a FRL, on air motors/cylinders/impacts - needing oil).

I have fought this water battle for years. I poke at our Process Engineers that they sometimes 'get air in our instrument water', and so ruin our actuators and my ability to control and automate systems. BTDT, got scars.;)

[Carroll Courtney]

To help the filter dryers is to install drip legs and to also have p-traps. Keep your compressor drain all the time will also help. I have water separators at each of my hose connections with a drip leg.

[Steve Jenkins]

I had a moisture problem years ago and purchased an after cooler from Grainger. It looks like a car radiator with a fan blowing through it. Works like a champ.

[Alan Lightstone]

I had a moisture problem years ago and purchased an after cooler from Grainger. It looks like a car radiator with a fan blowing through it. Works like a champ.

I took a look at those. How do they drain?

Also, a little fuzzy on how/where to install drip legs.

[Steve Jenkins]

I put a drip leg and moisture trap right after it

[Michael J Evans]

I'd recommend a standard filter and a dessicant dryer. You can also purchase filters that go right before the tool, but I believe those are more so for small debris.

[Charles Lent]

The posters above are right, the best approach is a refrigerated dryer to condense out and remove the moisture from your compressed air before you feed it into the lines in your shop. You will never have moisture problems at the air nozzles or spray guns, or air powered tools in your shop if you go this way, but refrigerated air dryers are not cheap, and the cost to run them can add to this.

When your air compressor runs, it squeezes the air together, leaving less room between the air molecules for the moisture molecules, but the compressing effort also heats up the air, so most of these moisture molecules can stay in the air, until the air cools off in your compressor tank. As it cools, the compressed air can no longer hold this moisture and it begins falling inside the tank, much like rain does from a cloud. If you can cool this air to the room temperature or below before you use it, you will not have air line moisture problems.

The air compressor manufacturers have put no effort into the design of your air compressor to make it more effective at removing moisture from the compressed air. They haven't even taken into account the fact that hot air rises and cool air falls in their design. They take the very hot compressed air directly from the compressor output and dump it directly into the top of the air storage tank. Then, right next to where that very hot compressed air enters the tank they provide the air outlet to your tools. The hot moist air from the compressor then just floats across the top of the tank like a hot air balloon floats above the cooler air and moves across the top of the tank and into your air lines, where it then gradually cools and the moisture in it begins to form water droplets that make it to your air tools and nozzles. It wouldn't be difficult at all for them to change their designs and make significant improvements to this problem.

If they had just added a finned radiator to the compressor outlet to fully cool the air to room temperature before it reaches the tank, the moisture would fall to the bottom of the tank. If they provided a tank connection for your air lines and tools that was about 1/2 way down the height of the tank, the air reaching it would already be cooler to at least to room temperature, and the air coming out of this outlet would be relatively free of the condensing moisture. You want cooled air to reach your tools and nozzles, not the very hot moist air as it comes directly out of the compressor. I have a repurposed small car air conditioner condenser coil (the one from in front of the car radiator) piped in between my small 2 hp air compressor and it's 20 gallon tank. This coil is also positioned so the fan in the center of the compressor pulley is drawing air through This coil. The bottom outlet of this condenser coil is piped to the original inlet on the top of the 20 gallon air compressor tank. The cooled air and it's condensed moisture enter the tank at the original location, but since the air is already cool the moisture quickly falls to the bottom of the tank, so it freely mixes with the cooled air in the tank and the condensed moisture falls to the bottom of the tank. When in use, I can drain as mush as 1/2 gallon of water from the bottom of the tank after each full day that I run this compressor, and I never have moisture problems at the tools or nozzles.

For added protection when using this air compressor for painting, etc. I bought a filter from the local auto paint supplier that uses a roll of toilet paper as it's filter cartridge. They sell a better version for this for about $1.50, but just one from the bathroom will work for several hours. It does indeed do a great job of removing any remaining moisture and debris from the lines when doing work that requires this. A refrigerated dryer is even better, but this is the best if you can't afford the refrigerated dryer.

I hope I have helped you all to understand the problems of getting dryer compressed air. A few relatively simple design changes can make a big difference to the dryness of your compressed air system. They are well worth doing, even if you end up getting a refrigerated system some day.

Charley

[Doug Dawson]

I put a drip leg and moisture trap right after it

Multiple drip legs, so to speak. I hesitated to respond to this, because the OP seems to be seeking a mobile solution. The easiest solution, and the only one I know of, is to have a passive piping system of some length, with repeated drops (and vertical takeoffs to the next leg.) That’s cheap and effective, but not mobile. Dessicants are useless when they’re saturated, FWIW.

[Frank Pratt]

What pressure is an AC condenser coil good for? I've been contemplating putting in some kind of heat exchanger between the compressor and tank.

[Michael W. Clark]

Multiple drip legs, so to speak. I hesitated to respond to this, because the OP seems to be seeking a mobile solution. The easiest solution, and the only one I know of, is to have a passive piping system of some length, with repeated drops (and vertical takeoffs to the next leg.) That’s cheap and effective, but not mobile. Dessicants are useless when they’re saturated, FWIW.

I did similar to this. I have 3 drops with a drain valve in each, the first one gets some moisture, the other 2 don’t. After the drops, I did a filter and regulator. I think they are Pneumatic Plus.

The radiator is interesting and I thought about that. I wasn’t sure on the pressure rating and I would prefer a separate fan instead of using the compressor cooling fan. The pipes were simpler for me.

[Robert Engel]

Alan,

I also live in FL so I know exactly what you're dealing with.

IMO you don't need an expensive dryer unless you're spraying a lot. I elected to buy a turbine sprayer rather than worry about moisture in compressed air.

I use an inline water separator, and with the Rapid Air piping system, each outlet block has a drain (which I've never used).

Also, the longer the runs are, the less issues you'll have.

[Brian Holcombe]

My compressor has a cooler and desiccant type dryer system, in addition to that it has a valve which automatically drains the tank multiple times through each cycle. On the line I have a filter/regulator/oiler at each tool. The air is clean, cool and dry.

[Alan Lightstone]

Multiple drip legs, so to speak. I hesitated to respond to this, because the OP seems to be seeking a mobile solution. The easiest solution, and the only one I know of, is to have a passive piping system of some length, with repeated drops (and vertical takeoffs to the next leg.) That’s cheap and effective, but not mobile. Dessicants are useless when they’re saturated, FWIW.

Actually, not looking for a mobile system. But also really didn't want to hard pipe, as all the DC and electrical piping go below the raised access floor in the workshop. The runs to the wide belt sander and two individual drops for tools are rubber tubing (or whatever that stuff is made of), not metal.

So there's really no vertical drop outside of perhaps the initial 2 feet from the compressor outlets to the floor. In fact, the run goes upwards at the end about 2-3 feet to the wide belt and outlets.

[Alan Lightstone]

Alan,

I also live in FL so I know exactly what you're dealing with.

IMO you don't need an expensive dryer unless you're spraying a lot. I elected to buy a turbine sprayer rather than worry about moisture in compressed air.

I use an inline water separator, and with the Rapid Air piping system, each outlet block has a drain (which I've never used).

Also, the longer the runs are, the less issues you'll have.

I use a turbine for spraying, so thankfully that isn't an issue, Robert. The runs are about 25-30 feet.

But blowing sawdust off a piece of wood just before I'm about to spray it, and have it spit water on it, is not what I expected/was looking for. And I worry if the water vapor might be ruining the mechanism in my wide belt sander (this may be a non-issue, but I've thought of it).

I had thought that the automatic drain valve on the tank would take care of this, but it clearly doesn't.

[Charles Lent]

What pressure is an AC condenser coil good for? I've been contemplating putting in some kind of heat exchanger between the compressor and tank.

Automotive air conditioners have as high as 350 psi working pressures on their condenser coils when the automotive air conditioners are running on very hot days. I've never seen a max pressure rating for one of these coils specified, but my air compressor systems never run over about 150 psi, so I decided that I'm safe to use one of these refrigeration condenser coils in my air compressor system. You might also want to consider using a large transmission oil cooler as an alternate to the refrigeration coil. The air conditioner coil that I have on my 2 hp 20 gallon unit has been in use for this purpose for almost 15 years. I have no idea how old it actually is. It has been trouble free, except for occasional leaks in my soft copper flare connections to and from it. These leaks are caused by the significant vibration that the unit has when it's operating. I'll likely be putting Blue Locktite on the flare fitting threads the next time I have to fix a leak, to see if that will help.

Charley

[Jim Becker]

What pressure is an AC condenser coil good for? I've been contemplating putting in some kind of heat exchanger between the compressor and tank.
Not sure about that, but the tubing might be too small in diameter for the application, even if it's up to the pressure task.

[Michael W. Clark]

Alan, I wonder if you are not getting the water out if your lines go down under the floor and back up to point of use?

If lines drop down from above, a drip leg will help separate free water simply using momentum and gravity of the water droplets.

I’m in TN and get a lot of humidity too, a lot more water in the summer.

[Tom Bender]

The A/C radiator is a good idea. It would be better to mount it independent from the vibrating monster.

[Tom Bender]

Charles, your analysis is good and precooling before the tank is a good solution. There is a second part to the condensation story. When the air goes back to atmospheric pressure at the spray gun or blowoff nozzle it gets cold, often below dew point and condensation from the room air can be generated. This is where it helps to get the compressed air to a much lower dew point.

[Ronald Blue]

If you were concerned the AC condenser might not have enough flow you could always mount two in parallel. You want a tube and fin style as well. The ones used in a lot of vehicles today are microchannel or more accurately a lot of tiny tubes close together. They can't be flushed out in the event of a ac system failure like a compressor grenading. While that shouldn't be an issue in a compressed air system they aren't what I would recommend. I service mobile hvac systems in my job.

[Brian Holcombe]

I ran heavy wall copper line for my system, it helps in this regard since the tube will dissipate heat. Whatever you decide, if you end up with a DIY solution make certain that you are within the industry recommended margin of safety for pressure and that it is approved for use with air (as opposed to fluids).

[Alan Lightstone]

Alan, I wonder if you are not getting the water out if your lines go down under the floor and back up to point of use?

If lines drop down from above, a drip leg will help separate free water simply using momentum and gravity of the water droplets.

I’m in TN and get a lot of humidity too, a lot more water in the summer.

Having the lines go down then back up is unchangeable in my workshop.

I just received the PneumaticPlus 3-stage air drying system, and a larger desiccant container. Not sure where to place it in the system, but thinking just before the wide belt sander and one of the air drops I use for tools and blowing off stuff.

Can't really think of a place to put a drip loop, considering the majority of the tubing is flexible tubing that runs under the floor, then comes up to the outlets.

[Doug Dawson]

Having the lines go down then back up is unchangeable in my workshop.

I just received the PneumaticPlus 3-stage air drying system, and a larger desiccant container. Not sure where to place it in the system, but thinking just before the wide belt sander and one of the air drops I use for tools and blowing off stuff.

Can't really think of a place to put a drip loop, considering the majority of the tubing is flexible tubing that runs under the floor, then comes up to the outlets.

The lines appear to be the lowest component in your system. What are you going to do when they fill up with water? How do you plan to drain them? This appears to be a deep structural problem. :^)

[John K Jordan]

Alan,

I use a home-made gravity trap before a water separator just in front of a desiccant dryer, this one: https://www.amazon.com/gp/product/B002PR8ZXK

This is in the main shop on the outside of my dust collector/air compressor closet.
448021
(Don't have a straight-on photo since it's in a narrow hallway.)

Never get water in the air line. Any water vapor that gets past these can still mess with plasma cutting so I use an inline desiccant dryer right at the input to the plasma cutter for extra protection.

BTW, the desiccant dryer is not designed to replace the desiccant - they want you to buy a new cartridge. Instead, I bought a spare cartridge (in case I broke it), pried it open, and replaced the desiccant beads with indicator desiccant. I do this every time now. Lots cheaper than a new cartridge. I "recharge" the desiccant in a toaster oven.

JKJ

[Michael J Evans]

Alan,

I use a home-made gravity trap before a water separator just in front of a desiccant dryer, this one: https://www.amazon.com/gp/product/B002PR8ZXK

This is in the main shop on the outside of my dust collector/air compressor closet.
448021
(Don't have a straight-on photo since it's in a narrow hallway.)

Never get water in the air line. Any water vapor that gets past these can still mess with plasma cutting so I use an inline desiccant dryer right at the input to the plasma cutter for extra protection.

BTW, the desiccant dryer is not designed to replace the desiccant - they want you to buy a new cartridge. Instead, I bought a spare cartridge (in case I broke it), pried it open, and replaced the desiccant beads with indicator desiccant. I do this every time now. Lots cheaper than a new cartridge. I "recharge" the desiccant in a toaster oven.

JKJ

I sell filters, lubricators, regulators, etc. There are dessicant dryers where you can buy just replacement beads.

[Ronald Blue]

We use this exclusively on our equipment. They are a little higher than most in cost but the desiccant cartridge will last a long time because it self cleans. These are high duty cycle in our applications because the air system on some equipment is cycling continuously in brake application every machine cycle. The only thing that fouls them is when the engine driven compressor begins to put oil into the air system. These are made by SKF.
https://lh3.googleusercontent.com/proxy/AOSixzNaRHI0pKHiK3rgo1S8d6hqTb7CU8uUaqKQ1g39I3VoL3 S9XFbPfrAJHLQ5n0dhVZqPPMihbOb6C_XD8Le3dC2u2BF5RiRv SPXcj1DeQBN6pdzi

[Alan Lightstone]

The lines appear to be the lowest component in your system. What are you going to do when they fill up with water? How do you plan to drain them? This appears to be a deep structural problem. :^)

True. I don't know the answer to that.

Will the compressed air push the water out of the lowest tubing and into the filter/desiccant cartridge?

[Alan Lightstone]

Alan,

I use a home-made gravity trap before a water separator just in front of a desiccant dryer, this one: https://www.amazon.com/gp/product/B002PR8ZXK

This is in the main shop on the outside of my dust collector/air compressor closet.
448021
(Don't have a straight-on photo since it's in a narrow hallway.)

Never get water in the air line. Any water vapor that gets past these can still mess with plasma cutting so I use an inline desiccant dryer right at the input to the plasma cutter for extra protection.

BTW, the desiccant dryer is not designed to replace the desiccant - they want you to buy a new cartridge. Instead, I bought a spare cartridge (in case I broke it), pried it open, and replaced the desiccant beads with indicator desiccant. I do this every time now. Lots cheaper than a new cartridge. I "recharge" the desiccant in a toaster oven.

JKJ

Nice setup, John. Very instructive. I'm assuming that the air comes into that system from behind the pressure valve, with the drip leg below it, then through the filters / desiccator and then to the manifold which dictates where it then goes?

[John K Jordan]

Nice setup, John. Very instructive. I'm assuming that the air comes into that system from behind the pressure valve, with the drip leg below it, then through the filters / desiccator and then to the manifold which dictates where it then goes?

Thanks - I put a lot of thought into it and designed it along with designing the shop building.

Yes, the air compressor is behind the wall in a sound-insulated closet with the dust collector. I wanted everything, including the motor disconnect, accessible from the main shop without having to go into the next room and into the closet. (I wired the dust collector controls the same way)

The drip, water separator, desiccator, regulator, and manifold are next. Behind the wall (in the closet) are lines to three RapidAir lines plumbed through the walls and ceiling to three zones, each with it's own cutoff valve in case one line were to develop a leak. I have compressed air outlets throughout the wood, welding, and little machine shop areas and one outside. This works very well down on the farm!

The accessible motor cutoff lets me easily cut power to the compressor when I'm leaving the shop. Once, in the daytime, fortunately, the pressure switch on the 5hp compressor stuck and the compressor ran continuously for a little while before I walked by the shop and heard it. I know a guy whose shop burned to the ground when his compressor ran continuously like that when he was not home. Ack!

JKJ

[Alex Zeller]

If it was me I would put a set up like John pictured on the wall. Instead of the pipe going through the wall I would just put a short hose with a disconnect on it that can be connected to your air compressor. Make it out of brass so it'll be colder than the air coming in and help condense the water. Where the air comes out you want that to be going up and then back down. You could even put a drip leg there although by that point the water should have been removed. When in use I would check to see what temperature the brass inlet pipe is. If it's room temp you are fine, which it most likely will be, but if it's warm then adding a radiator of some sort before the drip leg would be worthwhile.

[John K Jordan]

If it was me I would put a set up like John pictured on the wall. Instead of the pipe going through the wall I would just put a short hose with a disconnect on it that can be connected to your air compressor. Make it out of brass so it'll be colder than the air coming in and help condense the water. Where the air comes out you want that to be going up and then back down. You could even put a drip leg there although by that point the water should have been removed. When in use I would check to see what temperature the brass inlet pipe is. If it's room temp you are fine, which it most likely will be, but if it's warm then adding a radiator of some sort before the drip leg would be worthwhile.

Air people recommend about 20' of pipe before the dryers and such to give the air time to cool and the water vapor condense. Copper pipe is probably best, a long one would make a decent radiator. I've seen it recommended to slope this pipe upwards from the compressor so moisture runs back down away from the outlet and collect liquid before it reaches the compressor. I suspect if the copper line was too small diameter a high air flow might carry condensed water with it.

[Ronald Blue]

As I recall when I was involved in the locomotive rebuild there was 50 feet of line between the compressor and the reservoir for cooling purposes. There was also an after cooler at the compressor. The reservoir was equipped with a type of automatic drain valve that was constantly spitting roughly once per second. It was said to be more efficient than the type that blows air for several seconds every time the compressor unloaded. No other moisture removal device was used. Dry air is critical in a brake system and in cold weather operations. Cooling the air down helps with moisture removal. Air being discharged is at an elevated temperature and warm air more easily carries moisture. That's the benefit of cooling the air down.

[Charles Lent]

A friend of mine had mounted two 100 lb repurposed propane tanks upside down on the outside back wall of his shop, with the compressor installed inside the shop. Under the tanks he installed a large 3 way solenoid valve that was electrically connected to the compressor power source. When he turned on the air compressor, this valve closed and the air from the compressor filled both of the tanks. When he was done using the compressed air for the day and turned the power switch off, the 3 way valve switched off, dumping the compressed air from both tanks, along with any condensation that had built up in them. You didn't want to ever be anywhere in close proximity to this dumping cycle when it happened. The sudden roar when the 3 way valve opened to atmosphere, dumping the air in the tanks, would drop you to your knees, but he had no condensate build-up issues in the tanks.

Charley

[Alex Zeller]

A friend of mine had mounted two 100 lb repurposed propane tanks upside down on the outside back wall of his shop, with the compressor installed inside the shop. Under the tanks he installed a large 3 way solenoid valve that was electrically connected to the compressor power source. When he turned on the air compressor, this valve closed and the air from the compressor filled both of the tanks. When he was done using the compressed air for the day and turned the power switch off, the 3 way valve switched off, dumping the compressed air from both tanks, along with any condensation that had built up in them. You didn't want to ever be anywhere in close proximity to this dumping cycle when it happened. The sudden roar when the 3 way valve opened to atmosphere, dumping the air in the tanks, would drop you to your knees, but he had no condensate build-up issues in the tanks.

Charley

Reminds me of my bridge painting days. We used steel grit to remove the old paint. The 'pot' for the sand blaster was about 12' tall and on two semi trailer axles. It held something like 40 tons. We used two 2000 CFM air compressors connected to it. If I had to guess I would say it was easily 2000 gallons. At the end of the day I would manually open up the vent, a 2" steel pipe, and let it blow. By the time it vented the pipe was covered in ice.

[Ronald Blue]

Reminds me of my bridge painting days. We used steel grit to remove the old paint. The 'pot' for the sand blaster was about 12' tall and on two semi trailer axles. It held something like 40 tons. We used two 2000 CFM air compressors connected to it. If I had to guess I would say it was easily 2000 gallons. At the end of the day I would manually open up the vent, a 2" steel pipe, and let it blow. By the time it vented the pipe was covered in ice.

That reminds of a friend who used to have a welding shop. He routinely bid on work for one of the kind items and he got a contract to build some tanks for a cooking oil recycling business. These were large tanks that were several thousand gallons liquid capacity. I don't recall the length or diameter. One of the requirements was they had to be pressure tested. Not high pressure but 10 or 15 psi for a predetermined length of time. At the bottom there was a pipe nipple welded in. I think it was 6" in diameter. He had done the pressure test and his shop compressor had ran steady for hours and hours to finally build up the required pressure. So then it was time to release the pressure. Now this guy always has lived hard and fast as a little set up for the rest of the story. He backed his pickup up to the tank to stand on the bed while he removed the cap. Because after all there wasn't a lot of pressure in the tank. I don't recall how he removed the cap because I wasn't there. But when it let go it was not what he anticipated. He claimed it moved his truck several feet. The cap was blown out into a field and never recovered. Just one of his experiences he has had. He would do anything for you. But you don't always want him to.

[John K Jordan]

That reminds of a friend who used to have a welding shop. He routinely bid on work for one of the kind items and he got a contract to build some tanks for a cooking oil recycling business. These were large tanks that were several thousand gallons liquid capacity. I don't recall the length or diameter. One of the requirements was they had to be pressure tested. Not high pressure but 10 or 15 psi for a predetermined length of time. At the bottom there was a pipe nipple welded in. I think it was 6" in diameter. He had done the pressure test and his shop compressor had ran steady for hours and hours to finally build up the required pressure. So then it was time to release the pressure. Now this guy always has lived hard and fast as a little set up for the rest of the story. He backed his pickup up to the tank to stand on the bed while he removed the cap. Because after all there wasn't a lot of pressure in the tank. I don't recall how he removed the cap because I wasn't there. But when it let go it was not what he anticipated. He claimed it moved his truck several feet. The cap was blown out into a field and never recovered. Just one of his experiences he has had. He would do anything for you. But you don't always want him to.

I worked in a laboratory once where we tested pressure vessels. One thing we NEVER did above ground was test with air pressure - too much chance of catastrophic failure and explosive rupture of a weld since compressed gas contains so so much energy. Tests were done one of several ways - one was test for leaks with trace amounts of gas at very low pressure and check outside with a sensitive halon gas detector. Another method was to hydro test - fill with water then pressurize that - if the tank failed the release of even a tiny amount of water from a weld instantly dropped the high pressure in the entire tank to nothing and prevented an explosive rupture. To pressure test with air we used a crane to lower the tank into a large underground bunker built into the middle of the building.

The danger is the reason they hydro test gas cylinders.

[Ole Anderson]

An air drier would have come in handy yesterday. Working in the driveway on my 4 place snowmobile trailer trying to find a broken wire in my electric brakes. Had to remove the wheels. As the temperature dropped below freezing, my impact gun began to quit working. Traced it to moisture freezing in the quick connect at the gun. Sudden change in pressure as it entered the gun caused water to freeze in the connector and the gun to quit working. Good thing I had my 24" HF breaker bar. Salt on open threads for 8 years really causes problems. Had to chase threads on both the nuts and studs. All 20 of them. Turns out (at the last wheel removed of course) that the suspension at some point had bottomed out and crushed the brake wires, breaking three of them. All is now good.

Snowmobiling this year is going to be problematic as we generally are out long enough that we need to stop at a bar or restaurant for breakfast, lunch or dinner. No indoor dining this year in Michigan. Carry out just doesn't work when snowmobiling.

[John K Jordan]

....Traced it to moisture freezing in the quick connect at the gun. Sudden change in pressure as it entered the gun caused water to freeze in the connector and the gun to quit working. Good thing I had my 24" HF breaker bar....

Snowmobiling this year is going to be problematic as we generally are out long enough that we need to stop at a bar or restaurant for breakfast, lunch or dinner. ...

Huge temperature drop when gas expands. You can make dry ice that way.

But yikes, consider moving south! I grew up in Pennsylvania, a good place to be FROM. Been in TN for pert near 40 years now.
For extended playing in the cold I think I'd pack a lunch in an insulated bundle with a hot pack.

[Rob Sack]

What about using a heater core with a fan blowing across it? O'Reilly's had a copper unit with 5/8" hose inlet and outlet for around $60.00. By using a trans cooler or ac cooler, does the 5/16" or 3/8" inlet and outlet affect to air flow and/or volume?

[Charles Lent]

I don't think a heater core will stand up to the pressure, but an air conditioning condenser coil or a transmission oil cooler coil can handle it. Automotive air conditioner condenser coils typically see 350 psi pressures on hot days. Your air compressor won't have working pressures that high. Transmission oil pressures can run higher than that. Most of these coils have 5/8" or larger fitting sizes and the inlet usually feeds into 3 sections of the finned coils in A/C condenser coils, coming back together at the outlet fitting, so 3 sections of finned tubes all connected in parallel inside. The 5/8" fitting becomes the restriction or the pipes feeding or exiting it, in this case. You should be looking for a high pressure coil with inlet and outlet fittings at least as large as the lines on the compressor that will connect to it. Mount it so the compressor fan pulls air through it or add an electric fan that runs when the compressor runs. An automotive engine radiator or heater coil never sees more than about 30 psi, so it will not do for this application.

Charley

[Rob Sack]

Thanks for the information. All the transmission and ac coils I have found so far have either 5/16" or 3/8" fittings which would seem to be too restrictive. I will keep looking.

[Chris Fairbanks]

Sounds like the OP has his solution but for others looking for a more permanent solution check out a great thread on garage journal about using a radiator after cooler on air compressors. I ended up buying mine from Zoro. The whole goal of the thread is to condense out as much of the moisture before the air even gets to the tank by using an aftercooler/radiator right after the air exits the compressor head and then run it through a separator before going into the tank. Most folks are seeing the air temp drop 100-200f degrees from the output of the compressor through the after cooler. I am sure there are cheaper options than the one I bought but I got it a number of years ago on a 30% off coupon so the price was not to bad.

https://www.zoro.com/akg-air-cooled-aftercooler-max-hp-25-100-cfm-c-70100bg/i/G2111706/?q=G2111706

If posting this link is not acceptable search for “Compressor after Cooler” on Garage Journal and you will find it.

https://www.garagejournal.com/forum/showthread.php?t=50946 (https://www.garagejournal.com/forum/showthread.php?t=50946&goto=newpost)

[Alan Lightstone]

I have, for now a solution, but time will tell how well it will work, despite the cost involved.

I do have a question about the aftercoolers. Do they have a drain mechanism built into them (e.g. a drain valve)? If not, where does the water go?

[Harry Hall]

You might also want to consider using a large transmission oil cooler as an alternate to the refrigeration coil.

Charley


Hayden Automotive 402 Ultra-Cool Tube and Fin Transmission Cooler
this sells for $27 on the popular on line store ... I live in FL and have a 5hp 22gal compressor - you think if I copy your setup with this it might help?
Ed

[Malcolm McLeod]

I have not looked at every link provided in this thread, but the ones I have looked at do not have an auto-drain mechanism built in. You would need to install a drain in-line at the discharge of the after-cooler.

This could be as simple as a drip-leg with a manual valve. The drip-leg could be sized with a short(er) length of large(r) diameter pipe/tube, or a long(er) and small(er) diameter, to give you sufficient capacity for your typical usage (i.e. all the water produced in your typical air compressor session).

I have seen some folks use a small flow control valve here, instead of a ball valve drain. Set so there is just a hiss coming from it, it will bleed off the water, but not seriously impact the CFM of the compressor. It will also bleed off all your stored air when the system stops. I guess you could crack it open when you start the compressor, and close it when you're done .... but any way you slice it, it is still entirely a manual operation.

If you look at auto-drain options, they come in 2 general types:
1- Passive systems, typically a float opens the drain valve on high level in a filter bowl. Many FRLs use this mechanism in the filter and will be described as 'auto-drain'. One advantage is that it only operates when there's water present, so if the compressor is off, there's no water, the drain stays shut, and the system pressure will be preserved (assuming no leaks, of course). You may need to either install tubing to route the (water) flow to a suitable receptacle, or locate the filter in an area where the dripping water is not a nuisance.
2- Active systems - typically electronic 'dump' valves, that open on a timed sequence. A pair of individually settable on/off timers (i.e. 5min OFF & 0.5sec. ON) will open and close a solenoid valve to keep the water drained. This will give you positive feedback that the system is working - - you will hear it! Trust me. Downside is if you leave it powered, it will bleed off all your stored compressed air.

[Jim Becker]

Alan, if I recall accurately, I think it was Mike Hettrick who did a copper cooling/condensing system up and down his shop wall and somewhere in this very forum area should be photos.