Compressed Air - Storage Volume

The storage volume for a compressed gas can be calculated by using Boyle's Law

p_a V_a = p_c V_c

     = constant                                                (1)

where

p_a = atmospheric pressure (14.7 psia, 101.325 kPa)

V_a = volume of the gas at atmospheric pressure (cubic feet, m³)

p_c = pressure after compression (psi, kPa)

V_c = 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)

V_a = p_c V_c / p_a                                                        (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

V_a = (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 .