buickanddeere
Super Member
Could be because the tires were on airplanes and not ground vehicles.
trogen filled tires
- Thread starter meos1
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Could be because the tires were on airplanes and not ground vehicles.
CalG
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Jay
You don't have much experience with compressed air do you.
The air out of a compressor always leaves at 100% Relative humidity (often with liquid water unless there is a dryer in the system.
Well I guess this is my fault. I feel fine running the nitrogen on the firebird and the Cadillac....The others simply use compressed air(without a dryer)....One thing is for sure, I will never pay to top off.
dodge man
Super Star Member
I was always had the understanding that the nitrogen was to work out the swings in tire pressure due to temp. changes, hence the use in airplanes. BTW, the air I use has big molecules, its an Illinois thing, so the nitrogen wouldn't do me any good.
No, just with engineering and thermodynamics. Please tell me what the relative humidity is in your compressor air AFTER it is expanded to the pressure you run in your tires?
- Jay
GreenYellow
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I don't study compressors, engineering, or thermodynamics, but I can speak on this...
Relative humidity is determined by the amount of actual humidity in a volume of air at a specific temperature. Colder air can hold less moisture, therefore condensation occurs. Pressure has very little to do with it.
If a compressor intakes a volume of air, compresses it, them puts it into a tire, the same (basically) amount of actual (not relative) humidity is in the air. The compressor didn't magically make the water vanish. (This is assuming temperate is constant)
A compressor heats the air when it compresses it, this causing the ability to suspend more humidity in the air. When the air cools inside the tank, the relative humidity goes up, causing condensation. This is why you can sometimes see visible water vapor when shooting compressed air straight from a hose with no dryer.
If temperature is constant, the humidity and relative humidity inside a tire is the same as inside the compressor, and also the same as outside the compressor. (At a given point in time and a given temperature)
Jay, if there is water accumulated in your tank it can be quite a bit. All you have to do is put a blow gun on your line and hold it up to a hard surface and watch the water run down it.
CalG
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It's 100% if there is but ONE drop of liquid water in the tire volume.
And, in order for large changes in Pressure to occur with temperature change, the humidity level within the tire air volume need not be close to saturated. Run the numbers for yourself.
Put another way, If the RH is 50% for the uncompressed ambient air, what is the RH at 32 psig? If you say "over 100%" you will be right.
KennyG
Elite Member
Anybody ever find the inside of a tire wet when they dismounted it? I've taken a lot of tires off and never noticed a trace of moisture.
