I understand you to say that you know the “Normal” volume of a gas and want to know the actual volume at a specific temperature and pressure (both different from “Normal” conditions). If that is what you mean, then you can use the Ideal Gas Equation PV = nRT – but only if you know the molecular weight of the gas. A more conventional method of converting the volume is to use the result of combing simultaneous equations:
V2 = V1 (Z2/Z1) (P1/P2) (T2/T1)
V2 = gas volume at the new condition, m3;
V1 = “Normal” gas volume, m3;
P1 = 1.0 atm, absolute;
P2 = pressure at the new condition, atm., absolute;
T1 = 273 oK;
T2 = absolute temperature at new condition, oK.
The above equation is derived dividing one of the following equations by the other:
P2 V2 = Z2 n R T2
P1 V1 = Z1 n R T1
I hope this helps you out.