text: what mass of gas is needed to increase the gas pressure in a fixed volume cylinder from 3400psi to 3600psi? using nitrogen gas at a temp of 30 deg c and charging a cylinder of a fixed volume of 1000 ltrs/cm3 what is the extra mass/volume of gas required to increase the pressure in side the cylinder from 3400psi 3600psi as pressure is directly proportional to density. so for fixed volume pressure is directly proportional to mass so p1/p2 = m1/m2 p1=3400 p2=3600 m1= 1000 ltrs m2=x so we find m2=1058.82 ltrs so we need 58.82 ltrs convert into kgs by finding density of nitrogen gas. hope this helps