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. The drain on this
model is not on the very bottom of the lower tank, so I have to tilt the
unit to drain. If I don't have enough air to finish, I turn the unit on
with the drain open.
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
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
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.
When my Porter Cable pancake becomes difficult to lift, I drain it.
(Besides, any water in your tank will diminish the air storage as
water won't compress.)
Draining my vertical in the shop is a PITA, but I stole an idea from
Swingman to make that easier.
I'm buying a 90-degree fitting to replace the drain cock, and I am
going to run a length of brake line along the side of the tank to the
top where I will bend a swan neck and install the drain cock. It will
be at eye-height and the air pressure will push the water up the line
to an awaiting plastic bottle.
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.
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. Have you ever wondered why portable air tanks seldom if ever have no
bleeder valve for releasing water?
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.
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
I had never given that any thought... but I think that's related to
duty-cycle.. just not enough air going through to matter.
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
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
Or when he learned the cure for a "water logged" water well tank was to
drain it, because, while air compressed, water did not! ;)
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.
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
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.