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pressure vs altitude and temp vs pressure
Posted: Wed Dec 19, 2012 11:19 am
by mcapocci
Altitude Above Sea Level Absolute Barometer Absolute Atmospheric Pressure
feet meters inches Hg mm Hg psia kg/cm2 kPa
-5000 -1524 35.7 908 17.5 1.23 121
-4500 -1372 35.1 892 17.2 1.21 119
-4000 -1219 34.5 876 16.9 1.19 117
-3500 -1067 33.9 861 16.6 1.17 115
-3000 -914 33.3 846 16.4 1.15 113
-2500 -762 32.7 831 16.1 1.13 111
-2000 -610 32.1 816 15.8 1.11 109
-1500 -457 31.6 802 15.5 1.09 107
-1000 -305 31.0 788 15.2 1.07 105
-500 -152 30.5 774 15.0 1.05 103
01) 0 29.9 760 14.7 1.03 101
500 152 29.4 746 14.4 1.01 99.5
1000 305 28.9 733 14.2 0.997 97.7
1500 457 28.3 720 13.9 0.979 96.0
2000 610 27.8 707 13.7 0.961 94.2
2500 762 27.3 694 13.4 0.943 92.5
3000 914 26.8 681 13.2 0.926 90.8
3500 1067 26.3 669 12.9 0.909 89.1
4000 1219 25.8 656 12.7 0.893 87.5
4500 1372 25.4 644 12.5 0.876 85.9
5000 1524 24.9 632 12.2 0.860 84.3
6000 1829 24.0 609 11.8 0.828 81.2
7000 2134 23.1 586 11.3 0.797 78.2
8000 2438 22.2 564 10.9 0.768 75.3
9000 2743 21.4 543 10.5 0.739 72.4
10000 3048 20.6 523 10.1 0.711
15000 4572 16.9 429 8.29 0.583 57.2
Temp vs pressure is the ideal gas law. With a tire you can approximate a constant volume so pressure and temp are inversely proportional as long as you work in absolute temperature ratios. This is temperature Rankine or Kelvin. In Rankine you add 459 to the temp in degrees f for both the numerator and denominator. For temp kelvin add 273 to the temp in regress C
air pressure/altitude & travel tip
Posted: Wed Dec 19, 2012 1:31 pm
by mark ward
The big issue with Elivation and temps. is leakage!!!!
A pump bottle of bug spray (Glue's Oils, ETC ETC.) Can (WILL) LEAK at higher elivation or HOT temps. (80+)
TIP: So PACK EVERYTHING SEPERATE in ZIP-LOCK freezer bag's. (removing all excess air before sealing. (some people advise dbl sealing some items)
--- On Wed, 12/19/12, Mike Frey wrote:
From: Mike Frey
Subject: Re: [DSN_KLR650] Air pressure/altitude
To: "List KLR" DSN_KLR650@yahoogroups.com>
Date: Wednesday, December 19, 2012, 7:19 PM
>> Or 12,183 at the park above Estes park.
>> where potato chip bags look like they are about to BURST.
Yeah, that's fun in both directions. A Zip-Lock bag, closed up with a
half eaten sandwich at 10,000 feet, will look like it's been vacuum
sealed if you bring it back down to sea level.
Regarding tire pressures - disregarding barometer readings and air
temperatures - which, in aviation you just don't do, but in ground based
vehicles, it's OK to do - figure that if your tires is inflated to 20
psi at sea level, it will read about 25 psi at 10,000 feet.
Conversely, your 20 psi tire at 10,000 feet will read 15 psi when you
bring it down to sea level.
General (very "general") rule of thumb is:
5 psi increase for every 10,000 foot altitude increase, and
5 psi decrease for every 10,000 foot altitude decrease.
Mike
> Temps are also an issue.
>
> carry a $7-$12. tire gage and check regularly OR As you should anyways.
>
> In Death Valley, We went from 291ft BELOW sea level 1day And the next
> day 6168 above sea level, with out checking etc.
>
> Or 12,183 at the park above Estes park. where potato chip bags look
> like they are about to BURST.
>
> --- On Tue, 12/18/12, Bogdan Swider > wrote:
>
> From: Bogdan Swider >
> Subject: [DSN_KLR650] Air pressure/altitude
> To: "Bogdan Swider" >, "
DSN_KLR650@yahoogroups.com
> " DSN_KLR650@yahoogroups.com
> >
> Date: Tuesday, December 18, 2012, 10:36 PM
>
>
>
> Anyone know of a formula for how the air pressure in tires is affected by
> altitude ? I'll soon be going from 6000 feet, Colorado to St.Louis/Chicago
> - basically sea level. As often as I've done this you'd think I'd have
> looked into this before.
>
> Bogdan
>
> [Non-text portions of this message have been removed]
>
>
[Non-text portions of this message have been removed]