I just disposed of one (an old one) that rusted through. It manifest itself
through a pin hole leak in the bottom of the tank. I think if it had been
bled properly through out it's life, it would still be here.
If the condensate is rusty color, you know it is rusting.
I never leave air in my pancake compressor now. The pancake is easy to
drain. The old tank required getting down in my knees and looking under the
tank. I should have piped the drain to a valve located in the open where I
could see it. I would have drained the tank more often.
Yes and no.
Typically, the smaller the compressor, the less efficient, and the
more condensate it generates.
Not emptying the tank and bleeding off the condensate on a frequent
basis leads to problems.
You guys are making this too hard. It's just pV=nRT (ideal gas
1. Compressor takes in outside air, which typically has water vapor
in it, and packs it into the tank, thus raising the pressure.
2. As you let air out of the tank, the pressure drops. This cools the
air (as p goes down, do does T).
3. Cold air holds less moisture so liquid water condenses from the
water vapor and collects in the tank.
And thus condensing the water vapor into liquid. End of story.
Not correct. It was *already* condensed when under pressure. Water accumulates
in the tank during operation: air and water vapor, at ambient pressure, is
taken in by the compressor. As it is compressed, some of the water vapor
condenses into liquid and remains in the tank. Air withdrawn from the tank as
the tools are used contains less water vapor than the air that was taken in,
because some of the vapor remains behind in the tank as liquid. The longer the
compressor is operated, the more water will accumulate in the tank.
Doug Miller (alphageek at milmac dot com)
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.
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
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