Calculate the storage volume of compressed gas or air
The storage volume for a compressed gas can be calculated by using Boyle's Law
pa Va = pc Vc = constant (1)
pa = atmospheric pressure (14.7 psia, 101.325 kPa)
Va = volume of the gas at atmospheric pressure (cubic feet, m3)
pc = pressure after compression (psi, kPa)
Vc = volume of gas after compression (cubic feet, m3)
Volume of free gas in a Storage Volume
The amount of free gas at atmospheric pressure in a given volume - like a cylinder storage - can be calculated my modifying (1)
Va = pc Vc / pa (2)
Gas can be stored in high-pressure cylinders ranging to more than 6000 psig (410 bar). Normal-pressure cylinders are in the range 2000 and 2500 psig (140 and 175 bar) and low-pressure cylinders are in the range 480 psig (34 bar).
Example - Volume of Air in a Cylinder Storage
Standard atmospheric volume of air compressed in a 1.76 cubic feet K-type cylinder at 2200 psig (2214.7 psia) can be calculated
Va = (2214.7 psia) (1.76 cu ft) / (14.7 psia)
= 265 (cu ft)
In other words - if air in a 1.76 cubic feet container is compressed to 2200 psig - the same air at atmospheric pressure will occupy 265 cubic feet.