Barry King wrote:

> P is absolute pressure, i.e. atmosphere is about 32 psi absolute.

Atmosphere is about 14.7 psi absolute or 2116 lbs/sq.ft., not 32 psi
absolute.

> So for your example: from atmosphere to 100 psi gauge (psig) = 32 to
> 132 psia or a factor of 4.125 times the mass of air in the tank at
> constant temp.

14.7 to 114.7 = a factor of 7.80 times the mass of the air in the tank at
const. temp

> If you cool the air from 70F to 40F as well, that's only 530R to 500R
> (Rankine, absolute temp) or an additional 1.06 times the mass of air.
>
> Overall, a 4.37 times increase in density (mass of air in a given
> volume).

Overall, 1.06*7.8 = about 8.27 times increase in density.

Jim

> Regards,
>
> Barry.
> ------------
> Barry King
> NRG Systems "Measuring the Wind's Energy"
> http://www.nrgsystems.com
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