"willshak" wrote in message
...
Buck Turgidson wrote:

I have a CH 4 gallon twin tank. I never leave it full and usually run the
tool until the tanks are almost empty, then open the drain and allow the
low pressure to blow whatever water is there out.

Why do you drain under low pressure?

In article , "Mortimer Schnerd, RN" mschnerdatcarolina.rr.com wrote:
Doug Miller wrote:
1. Compressor takes in outside air, which typically has water vapor
in it, and packs it into the tank, thus raising the pressure.

And thus condensing the water vapor into liquid. End of story.


Only supersaturated air will condense upon compression. Normally, it won't
happen.

Incorrect. Consider that pressures of 135psig ( = 150psia, or 10 atmospheres)
are common even in small portable compressors.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

On Apr 27, 1:21 pm, "Leon" wrote:
"Robatoy" wrote in message

oups.com...



Water vapour condenses when the water/air mixture is
compressed...ASSUMING the temperature stays the same...which it won't
as air temperature increases when the pressure does during
compression...... so we wait till it cools to the original ambient
inle temperasture.... then it condenses.

Water vapor condenses regardless of pressure. Ever take a glass of ice
water out side on a hot humid day? You get condensation on the cool sides
of the glass. The condensation is formed when the humid air that has been
heated up during compression, enteres the cooler compressor tank.

That's what I said, and I quote, including some fat, laptop induced
typos: "so we wait till it cools to the original ambient inle
temperasture.... then it condenses"

IOW.. when it cools.

You can transfer humid compressed air to another container and there will
be no condensation inside the tank as long as the temperature remains the
same.

If the air being transferred is humid, it condenses when it cools.
When you move 100 gallons of 10% humid air into a 50 gallon container,
the air compresses, but the water does not. The air/water ratio will
therefore become 20%...by volume of humid air. I can put 400 gallons
of 14.psig air into a 50 gallon tank..and all the water will go in
there with it.
As the volume decreases, the temperature and pressure increase... but
the quantity of water stays the same.

IOW.. when I shove 100 gallons of air which contains 1 pint of water,
into a 50 gallon tank, the pressure and temperature go up
proportionally, but that pint of water stays a pint. Then when the
whole mess cools off, the dewpoint now changes and the increased
humidity condenses... and there is no way to reduce the quantity of
air's occupying space without heating it up in the process.
I think I got that right..LOL

Have you ever wondered why portable air tanks seldom if ever have no
bleeder valve for releasing water?

I had never given that any thought... but I think that's related to
duty-cycle.. just not enough air going through to matter.

On Fri, 27 Apr 2007 17:23:49 GMT, "Leon"
wrote:


"willshak" wrote in message
...
Buck Turgidson wrote:

I have a CH 4 gallon twin tank. I never leave it full and usually run the
tool until the tanks are almost empty, then open the drain and allow the
low pressure to blow whatever water is there out.

Why do you drain under low pressure?


I am not willshak, but I have observed (I have a Porter-Cable pancake
style compressor) that if I just open the drain valve when the tank is
pressurized, very little water comes out, even if I am holding the
tank so the valve is the lowest point.

It is only after the air has almost entirely bled out of the tank
(down around 30psi or so) that the bulk of the water is blown out. I
am not able to explain this observation, but it seems to always happen
that way.

I did leave it full once over a two week period because I was feeling
lazy and doing a lot of trim carpentry. The water that came out after
the two weeks was a nasty brown colour that convinced me the rust
warning was to be taken seriously. I now drain it at the end of every
day's work.

- Ken

"Robatoy" wrote in message
ps.com...

Water vapour condenses when the water/air mixture is
compressed...ASSUMING the temperature stays the same...which it won't
as air temperature increases when the pressure does during
compression...... so we wait till it cools to the original ambient
inle temperasture.... then it condenses.

Water vapor condenses regardless of pressure. Ever take a glass of ice
water out side on a hot humid day? You get condensation on the cool
sides
of the glass. The condensation is formed when the humid air that has
been
heated up during compression, enteres the cooler compressor tank.

That's what I said, and I quote, including some fat, laptop induced
typos: "so we wait till it cools to the original ambient inle
temperasture.... then it condenses"

IOW.. when it cools.


OK, I misunderstood, This part threw me, Water vapour condenses when the
water/air mixture is
compressed. I probably took that out of context. Sorry.
It'lneverhappenagainuntilnexttime. ;~)



Have you ever wondered why portable air tanks seldom if ever have no
bleeder valve for releasing water?

I had never given that any thought... but I think that's related to
duty-cycle.. just not enough air going through to matter.

That's probably ture too.

On Apr 27, 2:44 pm, "Leon" wrote:


OK, I misunderstood, This part threw me, Water vapour condenses when the
water/air mixture is
compressed.

It gets really interesting when the pressure gets to be so high that
the water in the air changes state from liquid to gas absorbing a lot
of heat due to latency... unless the pressure is REALLY high, then
water and steam change state without needing a whole lot of extra
heat(pressure)... by that time, your tank will be a decal on the
walls.
I have a headache now.... what walls?

In article , SWDeveloper wrote:

From my college physics class... There is a sealed room with two
bathtubs at normal temperatures and pressures. One bathtub is full of
water at 90 degrees F. The other bathtub is empty and has a
temperture of 72 degrees on the insides, the lowest temperture in the
room. What happens in this closed system is all the water will
evaporate from the 90-degree tub and the water vapor will condense
into the 72-degree tub. This makes sense why houses have damp
basements.

While that is all quite true, I'm not sure I see its significance to a
discussion of the behavior of water vapor when compressed to ten atmospheres.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

"B A R R Y" wrote in message
Robatoy wrote:
On Apr 27, 12:01 pm, B A R R Y wrote:

Must be bass players thinking alike...


Oh noes...... two solos, duet style?



We're going to get together and play "Big Bottom". G

IIRC, Willy had two bass players in one his bands ... but, and IIRC again,
it was pretty much a mess, even for a bass player.

As far as who did it first, I posted pretty much the same thing last year in
response to a similar post, but I doubt seriously the idea of using a drain
hose originated with me ... I was just looking for a way to drain the tank
without moving it, and the "unintended benefits" were too obvious for even a
coonass to miss.

--
www.e-woodshop.net
Last update: 2/20/07
KarlC@ (the obvious)

"Robatoy" wrote in message

I have a headache now.... what walls?

All I know is what any good country boy observed when putting his hay field
induced, sweaty brow against the wall of the water well tank ... sure does
feels good.

Or when he learned the cure for a "water logged" water well tank was to
drain it, because, while air compressed, water did not!

--
www.e-woodshop.net
Last update: 2/20/07
KarlC@ (the obvious)

On Fri, 27 Apr 2007 17:51:18 GMT, (Doug Miller)
wrote:

In article , "Mortimer Schnerd, RN" mschnerdatcarolina.rr.com wrote:
Doug Miller wrote:
1. Compressor takes in outside air, which typically has water vapor
in it, and packs it into the tank, thus raising the pressure.

And thus condensing the water vapor into liquid. End of story.


Only supersaturated air will condense upon compression. Normally, it won't
happen.

Incorrect. Consider that pressures of 135psig ( = 150psia, or 10 atmospheres)
are common even in small portable compressors.


From my college physics class... There is a sealed room with two
bathtubs at normal temperatures and pressures. One bathtub is full of
water at 90 degrees F. The other bathtub is empty and has a
temperture of 72 degrees on the insides, the lowest temperture in the
room. What happens in this closed system is all the water will
evaporate from the 90-degree tub and the water vapor will condense
into the 72-degree tub. This makes sense why houses have damp
basements.

"Morris Dovey" writes:
Swingman wrote:

| I moved the drain plug to the end of a 3' length of air hose on my
| small vertical, where it is much more accessible.
|
| The air hose holds quite a bit of water that would otherwise be in
| the tank, and, unlike the tank, is rustproof ... and gravity does
| the work.
|
| It is a simple matter to open the cock slightly every other day or
| so and let the water in the hose squirt out, and draining the tank
| this way doesn't even cause the compressor to cycle on.

Great idea - consider it stolen :-)


While you're down there, replace that silly stopcock with a real
ball-valve. Your fingers will be happier.

scott

"Leon" writes:

"DouginUtah" wrote in message
...
I have a 2 HP, 20 gallon Craftsman compressor. I drain it about every five
years and never release the pressure at the end of the day.

I have been using it since 1973.

It was getting really hot when shingling so I changed the oil last fall.
Don't know if that helped--maybe I just slowed down a bit. :-)


If you lived anywhere near the coast your compressor would have filled with
water in a couple of years.


I think that depends both on 'how near' and 'which coast'.

scott

B A R R Y writes:
Andy Dingley wrote:

In general, no. However a machine that has a slow leak down somewhere
and is going to be switched off for long enough to empty itself is
usually best vented deliberately rather than being left to do it
inevitably itself (or just fix the leak!)

Why is that?

It's like a Ni-cad. Let it get too empty and you can't fill it again.

scott.

(That there's a joke, son.)

"Michael Faurot" wrote in message
...
Tom Veatch firstname_lastname AT pixius dot net wrote:

Bottom line... it's probably better to dump the air when you're
done... at least for shop compressors.

Or:
http://www.harborfreight.com/cpi/cta...emnumber=42221


I bought one of these from HF, when I bought a new compressor
recently. I must have spent the better part of a day or so trying to
figure out a way to install this. The main problem I ran into is with
the air hose supplied and the compression fittings it uses.
Basically there weren't enough parts there to splice this device into
the system as they don't give you any additional compression fittings.
On my compressor, there's a solid copper line running between the
tank and the regulator. So I would need two more fittings to
rework things so that the automatic drain valve could be tee'd in
between the tank and the regulator.

I spent several hours trying to find more of those fittings locally,
but none of the hardware stores had them and HF itself does not
sell them. Perhaps a specialized industrial supply would have them,
but after spending a few hours trying to hunt stuff down, I gave
up and returned the device. The device itself probably works fine,
but you'd likely need to dig up some other type of way to splice
it into your system that uses some other type of fittings and hose.
It would be nice if they'd supply additional male and female
compression fittings with the device, even if that increased the
price of the device by a few bucks.

In the end, I found it's easy enough to just open the drain at the
bottom once a day and let it blow out the accumulated moisture.

--

If you want to reply via email, change the obvious words to numbers and
remove ".invalid".

You need a Grainger item # 4KT04
I screwed around with the HF drain valve, two of them in fact, and gave up
and spent the cash on this one. Easier to install, and it works.
Greg

"Swingman" wrote in message
...

All I know is what any good country boy observed when putting his hay
field
induced, sweaty brow against the wall of the water well tank ... sure does
feels good.

LOL,, and sticking the air nozzle, that is attached to the hose on your
compressor, inside your pants front pocket and lettin'er open up, really
feels good on a hot sweaty day. Your pants tend to inflate and it's like
wearing air conditioned pants.



Or when he learned the cure for a "water logged" water well tank was to
drain it, because, while air compressed, water did not!

--
www.e-woodshop.net
Last update: 2/20/07
KarlC@ (the obvious)

"SWDeveloper" wrote in message

From my college physics class... There is a sealed room with two

Besides DFTT, look up the verb "cavil" ... it may help you understand why
you are basically engaged in ****ing in the wind.

--
www.e-woodshop.net
Last update: 2/20/07
KarlC@ (the obvious)

Hot weather work apparel. Just what any well dressed Texan needs.
http://www.utilikilts.com/store/cust...products_id=19

"Leon" wrote in message
...

LOL,, and sticking the air nozzle, that is attached to the hose on your
compressor, inside your pants front pocket and lettin'er open up, really
feels good on a hot sweaty day. Your pants tend to inflate and it's like
wearing air conditioned pants.

"Leon" wrote in message
...

LOL,, and sticking the air nozzle, that is attached to the hose on your
compressor, inside your pants front pocket and lettin'er open up, really
feels good on a hot sweaty day. Your pants tend to inflate and it's like
wearing air conditioned pants.

OSHA might cite you for that. :-)

Don't use compressed air on your skin. They claim it can penetrate your skin
or something.
I'll do it on occasions though.

Could you imagine steadying the ladder for someone wearing that....And if he
is a true Irish Texan.....However I have heard of male postal workers
wearing the standard issue skirt because of objections to them wearing
shorts....


"CW" wrote in message
k.net...
Hot weather work apparel. Just what any well dressed Texan needs.
http://www.utilikilts.com/store/cust...products_id=19

On Fri, 27 Apr 2007 05:25:15 -0400, "Mortimer Schnerd, RN"
mschnerdatcarolina.rr.com wrote:

Maximum pressure 100psi? Make it something similar...


Well, I figured it was worth 10 bucks to try it out. When I went to
retrieve the URL, I noticed the 100psi limit. That may be new. I don't
recall noticing that limit at the time I bought one several months
ago. I run my 80 gal compressor at 135 psi shutoff and haven't seen
any adverse effects.

Every few days, or whenever I think about it, I open the manual drain
valve to verify that it's keeping the tank dry. So far, since
installing the automatic drain, I've never had a drop of condensation
come out the manual drain when I check it.

I'm satisfied.

On Fri, 27 Apr 2007 16:31:35 GMT, "CW" wrote:

Doug's never wrong. Just ask him, he'll tell you.

Look at a state diagram for water. Below the critical
temperature/pressure, increasing pressure drives the liquid/vapor
equilibrium point toward more liquid/less vapor which enhances
condensation in a closed container. Point for Doug.

Decreasing temperature does the same. Below the critical
temperature/pressure the reverse is also true; increasing temperature
enhances evaporation in a closed container. Point for Kevin/Mortimer.

Critical temperature is the temperature above which water cannot exist
in a liquid state no matter how much pressure is applied. For water,
that is about 374C or 705F. Critical pressure is essentially the vapor
pressure at critical temperature; about 217.7 atmospheres or 3200 psi.

Also note that the pressures involved are the partial pressures of the
individual gases, not the total pressure of a mixture of gases. In a
container of atmospheric air at total pressure of 10 atmospheres, the
partial pressure of the water vapor will vary depending on the
absolute humidity of the air, but it will be much less than 10 atm.

The equilibrium point (mass of liquid vs mass of vapor) in a closed
container is a function of both temperature and pressure. Doug, Kevin,
and Mortimer are simply arguing opposite sides of the same coin.

"Doug" wrote in message
oups.com...
On Apr 26, 7:57 pm, lwhaley wrote:
On Apr 26, 6:50 pm, "Buck Turgidson" wrote:

Partially out of laziness, inertia, procrastination, and partially
because I
use it several times a month, I leave my Porter Cable air compressor
full.
Does this do longterm harm to the machine?

no

I've been led to believe that the compressed air will create moisture/
condensation in the unit which obviously can do damage. I usually try
to remember to bleed mine.


Close but not quite. It's the act of compressing the air that causes the
water build up in the tank. Drain it before you use it and you'll find
yourself well enough protected in practical terms, for the life of the
compressor.

--

-Mike-

"Mike Marlow" wrote in message
...



Close but not quite. It's the act of compressing the air that causes the
water build up in the tank.

It's the heat generated during compression that causes condensation to build
up in the tank. Compress air with out changing the temperature and you have
no condensation during that process.

"Lowell Holmes" wrote in message
news:4SwYh.58$IJ3.30@trnddc07...

"Leon" wrote in message
...

LOL,, and sticking the air nozzle, that is attached to the hose on your
compressor, inside your pants front pocket and lettin'er open up, really
feels good on a hot sweaty day. Your pants tend to inflate and it's like
wearing air conditioned pants.

OSHA might cite you for that. :-)

Don't use compressed air on your skin. They claim it can penetrate your
skin or something.
I'll do it on occasions though.


LOL, I do it all the time but obviously don't blow it where you should not
and don't blow extreme pressures where you should not.

"Leon" wrote in message
t...

"Mike Marlow" wrote in message
...



Close but not quite. It's the act of compressing the air that causes the
water build up in the tank.

It's the heat generated during compression that causes condensation to
build up in the tank. Compress air with out changing the temperature and
you have no condensation during that process.

It is actually the cooler tank and air lines that causes the vapor in the
heated air to condense. That is why large systems use refrigerated dryers.
The moisture is already in the air, compressing it concentrates it into a
smaller area.

"Leon" wrote in message

"Mike Marlow" wrote in message

Close but not quite. It's the act of compressing the air that causes
the
water build up in the tank.

It's the heat generated during compression that causes condensation to
build
up in the tank. Compress air with out changing the temperature and you
have
no condensation during that process.

Yeah, we really do need a good isothermal shop compressor on the market.

.... until then we'll have to live with Charles's Law.

--
www.e-woodshop.net
Last update: 2/20/07
KarlC@ (the obvious)

"Swingman" wrote in message
...

RCH's are being unnecessarily split on this subject ... it matters not
that
you blame death by gunshot on the gun, the shooter, or the trauma from the
bullet, you're still dead.

Are you sure that dead horse is not going to get up??? What if I kick it a
couple more times? LOL

All you guys should go back and review the components of the Ideal Gas
Laws.
By the time you've compressed all the science contained therein into your
brain tanks, all the silly hot air on the subject will have evaporated.

Yeah, I'm sure there are more factors that come into play past the simple
fact that warm humid air meeting up with a cooler surface is going to cause
condensation.




--
www.e-woodshop.net
Last update: 2/20/07
KarlC@ (the obvious)

"Swingman" wrote in message
...


Yeah, we really do need a good isothermal shop compressor on the market.

... until then we'll have to live with Charles's Law.


Perhaps an electric blanket on the outside of the compressor. Then we could
worry about what to do with the condensation on the outside of the tank.
;~)

"Swingman" wrote in message
RCH's are being unnecessarily split on this subject ... it matters not
that
you blame death by gunshot on the gun, the shooter, or the trauma from the
bullet, you're still dead.

Yes, but it is either split hairs this morning or go out and clean up the
yard.

Swingman wrote:

| Yeah, we really do need a good isothermal shop compressor on the
| market.

I'd be happy to settle for an adiabatic discussion...

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/Absorber.html

"Edwin Pawlowski"

"Leon" wrote in message


"Mike Marlow" wrote in message




Close but not quite. It's the act of compressing the air that causes
the
water build up in the tank.

It's the heat generated during compression that causes condensation to
build up in the tank. Compress air with out changing the temperature
and
you have no condensation during that process.

It is actually the cooler tank and air lines that causes the vapor in the
heated air to condense. That is why large systems use refrigerated
dryers.
The moisture is already in the air, compressing it concentrates it into a
smaller area.

RCH's are being unnecessarily split on this subject ... it matters not that
you blame death by gunshot on the gun, the shooter, or the trauma from the
bullet, you're still dead.

All you guys should go back and review the components of the Ideal Gas Laws.
By the time you've compressed all the science contained therein into your
brain tanks, all the silly hot air on the subject will have evaporated.

--
www.e-woodshop.net
Last update: 2/20/07
KarlC@ (the obvious)

"Edwin Pawlowski" wrote in message
et...

"Swingman" wrote in message
RCH's are being unnecessarily split on this subject ... it matters not
that
you blame death by gunshot on the gun, the shooter, or the trauma from
the
bullet, you're still dead.

Yes, but it is either split hairs this morning or go out and clean up the
yard.


ROTFLMAO..... At least you and I know what we are talking about.. ;~) LOL

"Morris Dovey" wrote in message
...
Swingman wrote:

| Yeah, we really do need a good isothermal shop compressor on the
| market.

I'd be happy to settle for an adiabatic discussion...

Would that theory be economically possible in this situation?

In article , "Leon" wrote:

"Mike Marlow" wrote in message
...



Close but not quite. It's the act of compressing the air that causes the
water build up in the tank.

It's the heat generated during compression that causes condensation to build
up in the tank. Compress air with out changing the temperature and you have
no condensation during that process.

This is simply false. Heating causes *evaporation*, not condensation.

Vapor condenses into liquid when it is either compressed, or cooled, or both.
But *never* when heated unless simultaneously compressed by an even greater
factor.

--
Regards,
Doug Miller (alphageek at milmac dot com)

It's time to throw all their damned tea in the harbor again.

Leon wrote:
| "Morris Dovey" wrote in message
| ...
|| Swingman wrote:
||
||| Yeah, we really do need a good isothermal shop compressor on the
||| market.
||
|| I'd be happy to settle for an adiabatic discussion...
|
| Would that theory be economically possible in this situation?

In theory, yes - but (as we all know) in theory there is no difference
between theory and reality, but in reality there is... :-|

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA
http://www.iedu.com/DeSoto/Absorber.html

On Apr 28, 11:38 am, (Doug Miller) wrote:
In article , "Leon" wrote:



"Mike Marlow" wrote in message
[snip]

This is simply false.
Either you don't remember what you wrote,
you have a language comprehension problem
you're just a liar.
falsely claimed
attempting to deceive
you mischaracterized what you wrote.
And that's dishonest.
And so are you.
Regards,
Doug Miller

There, let's get this over with.

oh.. AND DON'T FEED THE TROLL!!!!!

Doug Miller wrote:
In article , "Leon" wrote:


You are on the right track.
Actually the compressed air does not create the condensation. It is the
heat generated from compressing the humid air that causes the condensation.


Incorrect. It is *exactly* the compression that causes the condensation: water
that is vapor at ambient pressure can be condensed into liquid by increasing
the pressure.
After reading your post, it reminded me of the fact that in order to
bottle liquid oxygen, they have to cool *and* put it under high pressure
to get it to condense to a liquid, but I never would have thought to
apply this principle to an everyday compressor. Good info.

"Robatoy" wrote in message
oups.com...


oh.. AND DON'T FEED THE TROLL!!!!!


Which one!
I see quite a few in this thread! ;-)
Greg

You quoted him so I saw what Doug Miller had to say and,,,,,

I must say, isn't it polite jesture how Doug always ends his often toxic and
condecending comments with,

Regards,
Doug Miller


LOL

Doug Miller wrote:
In article , "Leon"
wrote:


You are on the right track.
Actually the compressed air does not create the condensation. It is
the heat generated from compressing the humid air that causes the
condensation.

Incorrect. It is *exactly* the compression that causes the condensation:
water that is vapor at ambient pressure can be condensed into liquid by
increasing the pressure.



So Doug, I suspect you believe it is the pressure from "your firm grip" on
a glass of ice water that causes the warm humid air surrounding the glass to
cause condensation on the cool side of the glass.