Draining condensate from air compressor

[mark mcfarlane]

For the last 2 years I have been opening up the ball valve at the bottom of my 20 gallon IR air compressor (https://www.amazon.com/Garage-P1-5IU-A9-Gallon-Portable-Compressor/dp/B002Y095UU) tank to drain off any accumulated water. I had been contemplating an auto drain valve that opens on every cycle, but no water ever came out. Then I realized the valve isn't at he bottom of the rounded tank, its slightly higher than the lowest point, so I titled the tank and a bunch of water came out.

The compressor is kept in conditioned space so, even though I am in south Texas, the AC is running almost year round, and heated a few weeks in the winter,

So what do people do to maintain/properly drain these tanks? Tilt it all the time? What is the value of an auto drain if there is still water in the bottom of the tank below the valve height.

[Rob Charles]

INHO, an auto drain is well worth the cost & effort to install. Some types will still allow some residual water pooling in the tank. My practice has been when installing an auto drain is to put sufficient piping between the tank & valve in an attempt to have any water pool in the piping between the valve & tank vice in the tank.

[Tom Bender]

The inside of a compressor tank will always be damp unless there is a dryer between it and the compressor. The difference between damp and a little water is insignificant.

An auto drain is a fine idea. As an alternative you could put an extension on the valve handle so you don't have to bend down under the task to open it.

[Jacob Reverb]

The inside of a compressor tank will always be damp unless there is a dryer between it and the compressor. The difference between damp and a little water is insignificant.

An auto drain is a fine idea. As an alternative you could put an extension on the valve handle so you don't have to bend down under the task to open it.

+1

I suspect the tank is always going to be at least wet on its interior surface, with a RH of 100%, unless you completely drain the tank of water and let out all the compressed air every time you use it. The main thing you want to avoid is losing a lot of storage volume due to accumulated water.

[Derek Arita]

So rust isn't the issue?

[Bill Dufour]

I have always wondered about the point of galvanized pipe used inside. Buried in dirt the zinc prevents exterior rust. But the inside, which is wet all the time, has no zinc whatsoever.
Bil lD

[Jim Becker]

I have an IR automatic drain system on my compressor...it periodically exhausts just a little bit of air and with it, any condensate. The drain on my compressor (vertical tank) is at the very bottom of the tank...no place for anything to collect that wouldn't be blown out with the air. Remember, the auto drain attaches to the drain and the drain "should" be at the lowest point on the tank.

[Ken Fitzgerald]

Like Jim I have an automatic drain on my vertical 26 gallon air compressor.

Why have one? Prevent or slow down the tank rusting out. I have an acquaintance who lives in a rural area nearby. In an effort to fight of the effects of aging every morning he walks 3 miles in the hilly area where he lives. One morning while walking by the home of his nearest neighbor he saw his neighbor had a garage fire. JR said in an effort to save some tools from the guys garage the two of them could barely roll his air compressor from the garage because it was filled with water. I worry more about the tank exploding after rust weakens the tank.

[ChrisA Edwards]

I have read treads, like this, with interest. I have a 20 gallon, 20 year old Sears compressor that I had never drained.

It's lived with me from CT, MD, NJ, FL, TX and TX in an unheated or air conditioned garage.

It's on all the time and set to 120psi. My pipes leak a little and it cycles a couple of times a day when not in real use.

I decided to drain it, after reading a similar thread, so I wheeled it outside, expecting a gallon or two of water to come out.

This is all I got, about 4 drops of rusty brown water.

https://i1094.photobucket.com/albums/i452/cedwards874/Bike%20Stuff/CompressorDrain.jpg

[Randall J Cox]

Hopefully you got compressed air out with it. If not, it could very well be clogged with rust so that's all that came out. I don't use mine all that often so I always turn it off and drain it when done using it. Its an upright tank with a bottom drain, that I added some piping to and extended the valve out to the front so I didn't have to get under the tank to do it - back is getting old! ha Randy

[Mike Kees]

My air compressor at the shop is a 60 gallon vertical Ingersoll-Rand. I have it set up on a mezzanine. I wanted to install an auto drain but the one I purchased did not fit. I went to a local parts store and got plastic brake line and fittings and installed it with the line like 12' long so it hangs down to the floor. On the end I have a ball valve installed and simply hold it over the sink and drain without having to climb up to the mezzanine. Have always drained my compressors on a regular basis as well as change oil in them. Had a Bostich twin tank that is now 35 plus years old,sold it to one of my ex employees, he is still using it.

[mark mcfarlane]

Thanks everyone for your responses.

The drain on my IR tank is near the bottom, but on the side as seen in pic below. There could be maybe 3/4" of accumulated water in the tank below the drain point.

For the first ~two years of use I never got any water out opening the drain, until I tipped the tank last month. There is no plug at the exact bottom of the tank, just the valve in the picture.

.419524

The rust looking stains on the tank aren't surface rust, just splash from when I tipped the tank to drain it.

So auto drain or manual drain, I can't get all the water out unless I manually tilt the tank. Maybe this 3/4" of water is nothing to worry about.

[Tom M King]

The first thing I do on my little compressors is to change that little butterfly valve to a ball valve. Those little valves can get clogged just with dirty water from inside the tank.

[Donald Hofmann]

I live in Texas. Hot and humid here! My first compressor lasted 20 years before rusting through. I very seldom drained it. We did put motor oil in the tank to make it last longer. Since we only used that compressor for farm work and not painting or woodworking the oil wasn't a problem. I now have a new shop compressor and I drain it every time I use it. My small Bostich pancake compressor gets drained about every other time.

[mreza Salav]

I always drain (air and water) the tank after each day of use and leave the valve open. Next time I want to use the compressor close the valve and start it up.

[Bill Dufour]

A quality tank has the drain port flush to the tank bottom or a dip tube down to the bottom inside the tank.
Bil lD

[Zachary Hoyt]

I bought a used small compressor/inflator machine at an auction 10 years ago or so. It has a sticker on it that says "drain tank daily to prevent water accumulation" or something to that effect. I could never find a drain on it, it had a kind of plastic cowling over all of the moving parts. Finally one day I decided to find the drain so I took the cover off and found out that it has no tank, it just goes straight from the compressor to the air hose connection. There's also no drain valve anywhere on it. I guess someone in the corporate offices must have issued an edict that all compressors were to have the "drain" sticker on them, and no one noticed that it wasn't possible on this one.
Zach

[Jay Kepley]

Good morning! I'm setting up shop now, and I've been reading about air compressor set up and maintenance. I've read that if you leave your system under pressure all the time (which works great if you don't have leaks), there is very little water build up in the tank. I read somewhere that it's the pressure buildup that creates the condensation. If that's so, then opening up the tank to drain it promotes condensation. One post above seems to be consistent with what I read. I'd be interested in folks' thoughts.

[Edward Dyas]

For the last 2 years I have been opening up the ball valve at the bottom of my 20 gallon IR air compressor (https://www.amazon.com/Garage-P1-5IU-A9-Gallon-Portable-Compressor/dp/B002Y095UU) tank to drain off any accumulated water. I had been contemplating an auto drain valve that opens on every cycle, but no water ever came out. Then I realized the valve isn't at he bottom of the rounded tank, its slightly higher than the lowest point, so I titled the tank and a bunch of water came out.

The compressor is kept in conditioned space so, even though I am in south Texas, the AC is running almost year round, and heated a few weeks in the winter,

So what do people do to maintain/properly drain these tanks? Tilt it all the time? What is the value of an auto drain if there is still water in the bottom of the tank below the valve height.The auto drain isn't going to do anything that you couldn't do yourself. The tank would still need to be tilted to where the drain hole is. Is the compressor oilless? you could just prop it over to where the drain hole is all the time. If it's an oiled compressor with enough angle it might get starved for oil.

I worked with a guy for a week onetime that at the end of every single day he let all the air out of the compressor. I finally got the nerve to ask him why he did that and he said the instructions said to drain the compressor daily. I had to tell him they meant water. I think the compressor was half full of water when he drained it that day.

[mark mcfarlane]

The auto drain isn't going to do anything that you couldn't do yourself. The tank would still need to be tilted to where the drain hole is. Is the compressor oilless? you could just prop it over to where the drain hole is all the time. If it's an oiled compressor with enough angle it might get starved for oil.
...

Thanks Edward, the pump uses oil, so a permanent tilt won't work, but a great idea.

There may or may not be a tube running down to the bottom of the tank from the water bleed valve, but I doubt it exists. This is a $600 residential compressor.

[glenn bradley]

The drain on my IR tank is near the bottom, but on the side as seen in pic below.

I have also had compressors with the drain a bit higher than it seems like it should be. I have never heard a good explanation of what appears to be an often repeated design flaw. Anyone know why they do this? Why not bottom-dead-center"?

[mark mcfarlane]

I have also had compressors with the drain a bit higher than it seems like it should be. I have never heard a good explanation of what appears to be an often repeated design flaw. Anyone know why they do this? Why not bottom-dead-center"?

On a portable compressor, such as my IR, moving the valve a little off center provides a little bit of protection from banging it on something when wheeling around. Putting it dead center would also require making the compressor higher off the ground, raising the center of gravity a tad. Thats all I can think of.

[Mike Cutler]

For the last 2 years I have been opening up the ball valve at the bottom of my 20 gallon IR air compressor (https://www.amazon.com/Garage-P1-5IU-A9-Gallon-Portable-Compressor/dp/B002Y095UU) tank to drain off any accumulated water. I had been contemplating an auto drain valve that opens on every cycle, but no water ever came out. Then I realized the valve isn't at he bottom of the rounded tank, its slightly higher than the lowest point, so I titled the tank and a bunch of water came out.

The compressor is kept in conditioned space so, even though I am in south Texas, the AC is running almost year round, and heated a few weeks in the winter,

So what do people do to maintain/properly drain these tanks? Tilt it all the time? What is the value of an auto drain if there is still water in the bottom of the tank below the valve height.

Mark
If you're going to use an auto drain, don't set it up to open after every cycle. The moisture in the tank needs to condense first and then gravity will cause it to collect in the low spot. This won't happen immediately after each compressor cycle.
Why the drains aren't always on the bottom has been a good question. I understand all about the ideal gas laws and the effects of pressure and temperature on moisture, it would still be better to have it on the very bottom.
Don't depressurize your tank after every use. This completely defeats the purpose of the tank. The tank is the first stage of mechanical moisture separation in a system. Yes, it also functions as a reserve volume to reduce compressor cycles, but bring the tank up to pressure every time it's used, just introduces more moisture that needs to be gotten rid of.

[Doug Dawson]

Good morning! I'm setting up shop now, and I've been reading about air compressor set up and maintenance. I've read that if you leave your system under pressure all the time (which works great if you don't have leaks), there is very little water build up in the tank. I read somewhere that it's the pressure buildup that creates the condensation. If that's so, then opening up the tank to drain it promotes condensation. One post above seems to be consistent with what I read. I'd be interested in folks' thoughts.

That is pure moonshine. Whoever said that, has never run a still.

[mark mcfarlane]

Mark
If you're going to use an auto drain, don't set it up to open after every cycle. The moisture in the tank needs to condense first and then gravity will cause it to collect in the low spot. This won't happen immediately after each compressor cycle.
Why the drains aren't always on the bottom has been a good question. I understand all about the ideal gas laws and the effects of pressure and temperature on moisture, it would still be better to have it on the very bottom.
Don't depressurize your tank after every use. This completely defeats the purpose of the tank. The tank is the first stage of mechanical moisture separation in a system. Yes, it also functions as a reserve volume to reduce compressor cycles, but bring the tank up to pressure every time it's used, just introduces more moisture that needs to be gotten rid of.

Mike, I misspoke. The IR auto drain (https://www.ingersollrandproducts.com/content/dam/ir-products/documentlibrary/techpub/air-compressors/recip/electric-driven-two-stage/en-edv-2000-electric-condensate-drain-supplement.PDF) has a timer you set to open the drain for 0.5 - 10 second, every 0.5 - 45 mins. It's not a full tank drain. It had been a couple years since I read the manual and forgot how it worked. I never purchased the auto drain because I wasn't getting any water out of the tank even after 1 year of service (until I tilted the tank).

The auto drain probably is not of any value on this compressor in my environment if it takes a year to get enough water in the tank to reach the drain. I just need to manually tilt the compressor and drain once a month or something like that.

[Mike Cutler]

Mark

My Rolair JC 10 has the drain at about the 5:00 position. That compressor I do depressurize when I'm done with it, and then tilt it to get any accumulated moisture out of it. I rarely use this compressor though. It could be a year or more in between uses. My 60 gallon, Rolair, upright, is a different story. It's tank always remains pressurized. After each use though, I do isolate it from the system when I am done.

[Bruce Page]

The drain is smack dab at the bottom of my 30gal horizontal IR compressor. I added an IR ADV to it shortly after purchase. The ADV works great, I would quickly replace it if it were to die. It’s been 14 years and is still working. I later added a power switch to easily cycle the ADV. I only cycle it when I’m using air. I use a 5gal plastic can as a moisture trap. I have never needed to empty it thanks to the dry NM air. ;)

[Ken Fitzgerald]

My Husky 26 gallon vertical air compressor has the drain at the bottom. I added the ADV and it sticks out a bit but I never move this compressor. I have a small pancake compressor I use for inflating car tires and running my nailers, etc. when portability is required.

Unlike my friend Bruce, I leave my ADV plugged in and it cycles for 2 seconds, every 45 minutes. I do turn my compressor off when I leave the shop but the ADV remains on but that insures the tank is drained. Like Bruce, my ADV drains into a 6 gallon old paint bucket to contain the moisture in the bucket and to keep the hose from waving around when the compressor tank is charged to 140 psi when the ADC activates.

[Ole Anderson]

I wall mounted my previous compressor and tilted it slightly to the drain end and installed a ball valve which made it much easier to drain. Also a long nipple off the bottom to act as a water sump. I since replaced it with a 60 gallon 3.7 hp Kobalt compressor which will remain on the floor, but did install a ball valve there too.

Every time you discharge the air from your tank, it needs to be refilled with often moisture laden air. So, yes, if you drain the air every time you quit working you are likely going to end up with more water in your tank than if you don't. But if you drain the air and the water you are good to go. And folks living in humid areas will have more water issues than those in arid climates (which goes without saying, but I did anyway).