Jun 17th 2014, 03:08 PM
Join Date: Jun 2010
Location: Naperville, IL USA
The formula to use is the Ideal Gas Law:
where P=pressure, V=volume, n = amount of gas (in moles, or grams, or as in your case cubic feet at 1 atnmosphere), R is a constant, and T is temp in Kelvins. Adding more gas while maintaining the same size container and assuming the temperature in the tank is equalized with outside temp (and hence assumed to be constant) leads to:
P_2 = P_1(n_2/n_1)
In other words the pressure increases by the amount of gas you pump in. Double the amount of gas in the tank and you double the pressure. Going from 1338 ft^3 at 1 atmosphere to 1593 ft^3 will make the pressure:
P_2 = 1 atm(1593/1338) = 1.19 atmosphere.
Adding another 255 ft^3 brings it to:
P_2 = 1 atm(1848/1338) = 1.38 atmosphere. You can see that every time you add 255 ft^3 you increase the pressure by 0.19 atmospheres.