What happens when a compressor rusts out?

[Wade Lippman]

I don't use my compressor all that much, and drain it even less often.
Got around to it today and an ounce of rusty water blew out. That got me to wondering what happens when it fails.
Presumably all steel compressors fail eventually.
Do they just leak, or blow up? I suppose compressors wouldn't be all that popular if they blew up...

Just wondering.

[Gerry Grzadzinski]

There was a thread here about 2-3 months ago that alluded to them blowing up.
Almost scared me into buying a new one to replace my 30 year old craftsman.

[Ed Labadie]

The 2 I've had rust out simply started to leak.....

Ed

[Matt Day]

I think blowing up is a bit of a myth. I'd guess they'd just start leaking and not hold air.

[Bill Ryall]

I lost a 26 gallon tank a couple years ago. Pressurized to 125psi. Heard a cracking noise then the noise of escaping air. It was pretty obvious what had happened. Cutting the tank in half as a post-mortem revealed several rusted pits where the tank metal was paper thin. The tank was neglected by the prior owner, and was about 35 years old at the time.

As a matter of course, every Monday I have a calendar reminder set up to remind me to drain the condensate out of my shop tank. My portable gets depressurized prior to being transported, and I do that through the condensate drain to kill 2 birds with one stone.

[Lee Schierer]

When a compressor develops a leak, it flys around the room like a balloon until all the air escapes and then it lands on the floor flat as a piece of paper.

[Keith Outten]

http://www.sawmillcreek.org/showthre...sor-tank-rusts

[Jim German]

My air compressor is from 1932, still going strong!

That being said I am planning on replacing it soon, for this very reason and I've got it tucked behind 2000lbs of bridgeport just in case.

[Michael Yadfar]

It can explode, just look it up on Youtube, but I imagine it's rare

[guy knight]

sold a dual tank wheel barrow 5HP emglow to a friend told him it had a tank leak and to get it replaced before using it of course he didnt when it blew it was in the back of his pickup tank blew out and sent it 10 feet in the air and put a 6 inch deep 14 inch wide dent in his truck

[Curt Harms]

This seems like one of the benefits of extending the moisture drain with pipe. Not only is the valve in a position where it's easier to reach, water sits in the pipe rather than in the compressor tank. It's cheaper and easier to replace the extension pipe (if necessary) than it is to replace the tank. If it's easier to drain the tank maybe it'll get done more often.

[Robert Engel]

Its not gonna explode if its rusting through it will never build up enough pressure.

Which reminds me its been 6 months at least since I drained mine......

[Keith Weber]

You can buy a cheap auto drain that goes onto the bottom of the tank that allows you to set the number of minutes between drain valve openings, as well as the length of time that the drain valve remains open. They work fine, but for my intermittent use of air, I didn't want that thing going off all the time in my shop making noise when I wasn't using the air compressor. So, I decided to come up with my own adaptation of the pre-cooler concept used on higher-end air compressors.

Instead of the copper line coming straight out of the compressor head and into the tank, I rerouted it through a radiator/condenser mounted on the fan shroud, then through a good quality water-separating filter before going into the tank. At the end of a compression cycle, the copper line depressurizes (to allow for easy subsequent starts), and the filter's auto drain float "bumps" and any water collected in the filter drains out a hose into a little container. It works way better than I expected, with about 99% of the water never reaching the tank in the first place. It keeps my tank dry, and the air leaving the tank as well. The copper line leaving the compressor head gets hot enough to burn yourself on after a number of cycles (no change from before my mod), but the lower line leading to the filter is at room temperature or luke warm at best.

I am not in any way saying that this needs to be done in every air compressor -- it is just my overkill approach to a problem in my shop. A normal air compressor auto drain will do everything my setup will, and be cheaper. Mine just does it quieter and works on demand vs. on a timed interval. Just thought I'd share since the topic came up.

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[Peter Aeschliman]

You can buy a cheap auto drain that goes onto the bottom of the tank that allows you to set the number of minutes between drain valve openings, as well as the length of time that the drain valve remains open. They work fine, but for my intermittent use of air, I didn't want that thing going off all the time in my shop making noise when I wasn't using the air compressor. So, I decided to come up with my own adaptation of the pre-cooler concept used on higher-end air compressors.

Instead of the copper line coming straight out of the compressor head and into the tank, I rerouted it through a radiator/condenser mounted on the fan shroud, then through a good quality water-separating filter before going into the tank. At the end of a compression cycle, the copper line depressurizes (to allow for easy subsequent starts), and the filter's auto drain float "bumps" and any water collected in the filter drains out a hose into a little container. It works way better than I expected, with about 99% of the water never reaching the tank in the first place. It keeps my tank dry, and the air leaving the tank as well. The copper line leaving the compressor head gets hot enough to burn yourself on after a number of cycles (no change from before my mod), but the lower line leading to the filter is at room temperature or luke warm at best.

I am not in any way saying that this needs to be done in every air compressor -- it is just my overkill approach to a problem in my shop. A normal air compressor auto drain will do everything my setup will, and be cheaper. Mine just does it quieter and works on demand vs. on a timed interval. Just thought I'd share since the topic came up.

IMG_2036 copy 2.jpg IMG_2038 copy 2.jpg

Pretty slick! But isn't much of the moisture in the tank the result of pressure being released from the tank? You say your trap has a radiator in it, but I assume the best that radiator can do is bring the compressed air's temp down to the ambient temp of your shop right? Certainly your modification is a big improvement, but I assume you still have to drain your tank since the air gets much colder than ambient when you release pressure from the tank over the normal course of use, yes?

[Keith Weber]

Pretty slick! But isn't much of the moisture in the tank the result of pressure being released from the tank? You say your trap has a radiator in it, but I assume the best that radiator can do is bring the compressed air's temp down to the ambient temp of your shop right? Certainly your modification is a big improvement, but I assume you still have to drain your tank since the air gets much colder than ambient when you release pressure from the tank over the normal course of use, yes?

Peter,

The moisture in the tank is the result of the compression of the air. Picture taking an entire room full of air and compressing it down to the size of your tank (that is essentially what you are doing.) Consider that that room has 1/2 cup of water in the air. It doesn't feel overly humid because that 1/2 cup is dispersed throughout the room. When you compress that air into your tank, that same 1/2 cup of water will end up in your tank. That's just the physics of compressing air. You cannot prevent that moisture from getting into your compressor. The humidity of the air in the room will determine whether you'll end up with more or less than 1/2 cup, but whatever moisture is in the air you compress will end up in the tank.

What I'm doing is extracting that water before it gets to the tank. I do this by cooling the hot and humid compressed air. This cooling causes the water to condense out of the compressed air. Once cooled in the radiator/condenser, the liquid water trickles down the copper line to the water filter, where it is extracted. The air entering the tank on the other side of the water filter is very dry compared to the compressed air leaving the compressor.

You were right about the room temperature comment, and the fact that the room temperature tank air will cool further once it is released from the tank. But most of that expansion and cooling happens outside of the tank. My compressor will put out 27.5 cfm, so it never gets overly low inside the tank before it turns on again (150psi cutout and about 120psi cut in, I think (I'll have to check)). My mission was to take the bulk of the water out of the air so it does not sit in the tank. This setup does this remarkably well. I still use a refrigerated air dryer downstream of the tank for painting and sandblasting, as this takes care of the moisture issue in the air due to the further cooling to zero psi during those moisture critical operations. For other operations, I just use the air as is for now.

At the end of the day, I hit the bottom drain just to catch with a rag anything that was in the tank, but I never get anything more than you'd feel if you sneezed into the rag a couple of times. I once forgot to turn my compressor off at the end of the day when I left town for the months of January and February. I have a leaky hose down line, so the compressor will cycle about every 4-6 hours. When I got back a month later, I hit the bottom drain, expecting some water from the constant cycling. I'd say that I got about a tablespoon of water out of it, at most. I get to demo the setup a lot when I get visitors. I surprise even the seasoned air compressor veterans with how well it operates.