# Theory about air compressors



## GouletPens (Jul 16, 2009)

Okay, so I just bought a new air compressor, 60 gallon....and I know that you're supposed to drain the valve at the bottom of the tank to let the water out that's created during pressurization so the tank does rust out and blow up in your face. I get that. 

But I'm thinking about my hot water heater, which is a _glass-lined_ steel tank that holds nothing but scalding hot water for 15+ years under pressure and I'm thinking to myself, why can't they make glass-lined air compressor tanks??? It's not like price is a huge issue b/c my compressor new costs 3-4x more than my hot water heater. So why don't they use glass-lined tanks? Is it because the water would build up and then eventually come out with the air? I already have a water filter on my hoses, and you could surely put some kind of auto-draining water filter thing on it, right? I mean are commercial and industrial compressors designed the same way, where they have to be shut down and drained every day?

So really, can someone smarter than me please explain why we are all forced to drain our tanks every day?.....or are we!


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## mredburn (Jul 16, 2009)

The draining of your tank daily helps reduce moisture going through the lines and your air tools. This is important if you dont want gummy orings in your air nailer/staplers. It also reduces moisture in your finishes should you use a spray gun to apply them with. And if your really lucky moist air combined with air tool oil, discharged out onto your lovely project makes for the most interesting stain on unfinished wood.


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## jkeithrussell (Jul 16, 2009)

I don't know about the glass lining part, but there is no need to drain your tank daily.  I drain mine maybe once a month.  I use a filter to capture water coming out of the tank if I'm using the air during finishing or for my airbrush.


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## titan2 (Jul 16, 2009)

_You can also get an automatic drain opener.........you can set it for how often it drains and for how long.  The one I got a few years ago was around $100.......worth every cent!  No longer trying to get to the bottom of my 60gal tank to open the drain **** and fight the spiders who take up residence there!_
 
_Want to know how much water is squeezed out during compression.......use an orbital (air) sander for a little bit.......it'll start condensing in it and start spitting out water all over what you're sanding.  Those little pups really go through a lot of air!!!_
 
 
_Barney_


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## GouletPens (Jul 16, 2009)

Another thing I found annoying was that I WAS draining my tank daily (after every use, at least) on my porter cable pancake compressor, and after 6 months or so i went to move it and noticed there was water sloshing around in the tank! I pressurized it, and held the tank so the drain nozzle was the most downward point of the tank (it's normally a bit above the actual bottom of the tank in normal sitting position) and all kinds of brown (rusty) water spewed out. That's when I decided to put the water filter on the hoses. 

Couldn't you just put a heavy-duty water/rust filter on the line between the tank and hoses and not have to worry about rust and o-ring wear and whatnot?


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## GouletPens (Jul 16, 2009)

titan2 said:


> _You can also get an automatic drain opener.........you can set it for how often it drains and for how long. The one I got a few years ago was around $100.......worth every cent! No longer trying to get to the bottom of my 60gal tank to open the drain **** and fight the spiders who take up residence there!_
> 
> _Want to know how much water is squeezed out during compression.......use an orbital (air) sander for a little bit.......it'll start condensing in it and start spitting out water all over what you're sanding. Those little pups really go through a lot of air!!!_
> 
> ...


 Where'd you get your auto drain?


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## NewLondon88 (Jul 16, 2009)

GouletPens said:


> Another thing I found annoying was that I WAS draining my tank daily (after every use, at least) on my porter cable pancake compressor, and after 6 months or so i went to move it and noticed there was water sloshing around in the tank!



Not unusual .. I ran mine about 10 hours a day, drained it nightly and
still had to replace it every 6-8 months. I bought either the Porter Cable
or Campbell something or other pancake compressors. (tight space in a
closet) I've been through dozens of those


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## jleiwig (Jul 16, 2009)

Your water heater does not see anywhere near the pressure that a air compressor sees.  No glass lined tank would support air compressor type pressures.


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## GaryMadore (Jul 16, 2009)

Brian,

I take out the little finger-busting valve that comes with compressors and use plumbing fittings (nipples and elbows and a lever-actuated ball valve) to make a valve that's easy to access and operate... I usually set it up so that the ball valve sticks out about 6" in front of the compressor.

That way a quick crack-open and the built up (brown gungy) water is history.

An inline filter won't clean out that water: Condensation is a side-effect of compression and the water settles in the bottom of the tank.

Cheers!

Gary


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## DozerMite (Jul 16, 2009)

Most commercial or manufacturing compressors use a drier. You can purchase a compressor with one built in or add one to any compressor, but they aren't cheap. A line filter won't stop all the moisture, once the filter is saturated, the moisture will get through. Use a water seperator.

If you are concerned about your tank rusting out, you could get some of the gas tank coatings that seals the interior of gas tanks and coat your tank with it. It's poured in and rotated to coat the inside.


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## rjwolfe3 (Jul 16, 2009)

I'm bad about remembering to drain mine. Of course I maybe use the one in the garage one a month or so and my basement one only when I turn pens which lately hasn't been at all (thanks to Jeff and his wife, lol - new hobby!). I have had the one if the garage for many, many years and maybe drain it once a year if I remember. I'm not trying to tempt fate but just don't remember to do it.


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## GouletPens (Jul 16, 2009)

jleiwig said:


> Your water heater does not see anywhere near the pressure that a air compressor sees. No glass lined tank would support air compressor type pressures.


 I figured that might be the case:frown:


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## titan2 (Jul 17, 2009)

GouletPens said:


> Where'd you get your auto drain?


 
_I picked it up at the 'Air Tool Store' that I bought my compressor from.  They carry them all the time.......well worth the money and convenience!_
 
_Found this one on E-Bay that looks something like mine......_
__ 
http://cgi.ebay.com/AUTOMATIC-ELECT...temQQimsxZ20090625?IMSfp=TL090625186001r20495
 

_Barney_


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## jusjoe (Jul 18, 2009)

Here's the one I use at work and home.  Kind of pricey but I've never had to replace it neither.  Time and duration adjustable so you can adjust based on how much air you are using.  I just ran it to the sump pump pit in the basement.  

One of my best investments.

http://www.grainger.com/Grainger/ca...m-components/pneumatic-condensate-auto-drains


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## Randy_ (Jul 18, 2009)

GaryMadore said:


> Brian,
> 
> I take out the little finger-busting valve that comes with compressors and use plumbing fittings (nipples and elbows and a lever-actuated ball valve) to make a valve that's easy to access and operate... I usually set it up so that the ball valve sticks out about 6" in front of the compressor.
> 
> That way a quick crack-open and the built up (brown gungy) water is history......


 
I did the same thing with mine. Think the parts cost me about 10 bucks......maybe a dollar or two more??


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## GaryMadore (Jul 18, 2009)

Randy_ said:


> I did the same thing with mine. Think the parts cost me about 10 bucks......maybe a dollar or two more??



Yes Indeed, Randy: $10 or so, and all you gotta do is crack the valve open for a couple of seconds every once in a while and -bam- no more water.







http://www.penturners.org/photos/images/3502/1_plumbing.jpg

No muss, no fuss: Works for me

Cheers!

Gary


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## GouletPens (Jul 18, 2009)

GaryMadore said:


> Yes Indeed, Randy: $10 or so, and all you gotta do is crack the valve open for a couple of seconds every once in a while and -bam- no more water.
> 
> 
> 
> ...


 Hmmm...I guess you don't have to shut off the compressor and drain it completely every day, do you? I guess I just got in the habit of doing that and never really thought about it. But doing it that way I'm putting a lot more wear on my motor by having to completely pressurize it every time i need to use it. Just opening the drain valve (with the motor still on and under pressure) would shoot out all the water in just a few seconds! Duh:tongue:


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## KenV (Jul 18, 2009)

The tanks do not explode when rusted through -- they no longer hold air pressure and do hiss a lot.   Extening the drain with a good valve helps.  Putting a coating inside helps extend the life, but consider the tanks an expendable item.  Have used the orthophospate costings used to neutralize rust to extend life.  

Water pressure runs 15-40 psi and is pretty constant,  Air compressors run from zero to 90/120 psi and the expansion/contraction is not a strong feature for glass.  It tends to crack with the movement caused by the pressure (force) of the compressed air.

The water forms from vapor when the air cools in the tank -- Regardless of the drain system good filters and traps are a needed part of a compressed air system and do need periodic maintenance.


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## GaryMadore (Jul 18, 2009)

GouletPens said:


> Hmmm...I guess you don't have to shut off the compressor and drain it completely every day, do you?



I used to always drain my compressors completely too, until one day a friend asked me why. I had no idea, but just thought it was the thing to do. Nope: all that's required is to pop open the valve until water stops spraying out and that's it.

The motor doesn't have to be on, either: There's loads and loads of air available to force the water out. In fact, it'll run out on its own if the compressor is empty.

I got in the habit of shutting mine off and then purging the water at the end of the day.

Cheers!

Gary


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## titan2 (Jul 19, 2009)

GaryMadore said:


> Yes Indeed, Randy: $10 or so, and all you gotta do is crack the valve open for a couple of seconds every once in a while and -bam- no more water.
> 
> 
> 
> ...


 
With my automatic one, I don't have to worry about remembering to drain it and there's no water to catch and throw out or any water on the floor......it's all vented outside!
 
Barney


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## GaryMadore (Jul 19, 2009)

titan2 said:


> With my automatic one, I don't have to worry about remembering to drain it and there's no water to catch and throw out or any water on the floor......it's all vented outside!
> 
> Barney



True, but mine cost $10 and I can still use it if there's a power failure! ***

Cheers!

Gary

*** hee hee


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## intillzah (Jul 19, 2009)

I'm going to do this to my air compressor:

http://www.hammerzone.com/archives/workshop/compressor/drain/ball_valve.htm


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## GaryMadore (Jul 19, 2009)

intillzah said:


> I'm going to do this to my air compressor:
> 
> http://www.hammerzone.com/archives/workshop/compressor/drain/ball_valve.htm



Careful: He added a block of wood under the front in order to provide clearance for his valve. If this tilted the compressor such that the front is now higher than the back, the water will collect in the back and never be expelled.

This is one of two reasons I prefer vertical compressors (the other is floor space).

Cheers!

Gary


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## Randy_ (Jul 19, 2009)

The other thing I don't like about that particular installation it that the pipe seems to extend out quite a bit and looks like it could be damaged by careless passing traffic.  Think I would have used a shorter nipple or angled the pipe at about 45° to the tank so it wouldn't extend out so far.
 
Also in the configuration pictured, the air blast is aiming directly at the most likely location of the person draining the tank.  Instead of adding a 45° elbow at the end of the drain, I would have added a 90° elbow and pointed it "AWAY" from the valve handle!!


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## GaryMadore (Jul 19, 2009)

Randy_ said:


> The other thing I don't like about that particular installation it that the pipe seems to extend out quite a bit and looks like it could be damaged by careless passing traffic.  Think I would have used a shorter nipple or angled the pipe at about 45° to the tank so it wouldn't extend out so far.
> 
> Also in the configuration pictured, the air blast is aiming directly at the most likely location of the person draining the tank.  Instead of adding a 45° elbow at the end of the drain, I would have added a 90° elbow and pointed it "AWAY" from the valve handle!!



So, yeah, aside from what Randy and I said, it's an OK installation 

Cheers!

Gary


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