โApr-07-2021 05:07 PM
I may not have gone where I intended to go, but I think I have ended up where I needed to be
Douglas AdamsโApr-23-2021 12:24 PM
โApr-23-2021 05:42 AM
โApr-22-2021 01:19 PM
โApr-12-2021 04:30 AM
โApr-11-2021 03:09 PM
DrewE wrote:
Water vapor not near the dew point does indeed act as an ideal gas, for practical purposes.
Air from a compressor (at least in somewhat humid climates), if there is no dryer in the line, will be saturated and pretty close to the dew point at the tank pressure, as evidenced by the condensation that collects in the compressor tank. Tire pressure is lower than the tank pressure, which lowers the pressure dew point in the tire somewhat, but it's still well in the range of ambient conditions that a tire is likely to be exposed to.
While rubber is somewhat more permeable to water than to air, it's still a very slow process for it to get out. (It's still more permeable to carbon dioxide, and it takes a long time for a tire filled with that to deflate noticeably.)
โApr-11-2021 01:56 PM
โApr-11-2021 11:37 AM
CapriRacer wrote:DrewE wrote:
..... The only component of air that expands or contracts significantly differently than nitrogen alone is water vapor. .......
Sorry, that is not true.
Water vapor behaves like an ideal gas EXCEPT near the dew point. Even a tire with liquid water in it will eventually lose all that water through the sidewalls, and become like the outside air - which is normally NOT near the dew point.
โApr-11-2021 10:00 AM
fj12ryder wrote:ktmrfs wrote:Personally I think the less change in pressure is caused by the dryer nitrogen compared to regular air. There should be no water vapor in the nitrogen fill, and water vapor will expand and contract more than gases without the water vapor. JMO anyway.PartyOf Five wrote:
Our mechanic suggested nitrogen in the car tires if we did a rotation as winter approached. Apparentky it doesn't contract and expand as much in the cold and so is better in extreme temps.
That was already a few years ago- the fad seems to have died down.
NOT true. all gases follow boyles law PV=RT. since V (volume) is constant, P is strictly a function of T (temperature) where T is absolute temp, E.G. room temp is 273 or so Kelvin
Nitrogen molecules are slightly larger than Oxygen, so pressure drop from migration through the tire will be very slightly less.
But basically unnecessary, just a way for some place to make a few extra pence.
โApr-11-2021 09:58 AM
โApr-09-2021 12:42 PM
โApr-09-2021 04:05 AM
DrewE wrote:
..... The only component of air that expands or contracts significantly differently than nitrogen alone is water vapor. .......
โApr-08-2021 10:33 AM
I may not have gone where I intended to go, but I think I have ended up where I needed to be
Douglas AdamsโApr-08-2021 10:05 AM
โApr-08-2021 09:51 AM