How to calculate natural gas quantity in known volume of pipe?

The quantity of gas in a given volume can be determined by two important gas equations. PV=nrT relates pressure and volume to the Ideal Gas Law constant, the amount of moles of gas and the system temperature. Once the system of the pressure (in atms), temperature (degrees Kelvin), gas constant (.0821 L*atm*K^-1*mol*-1), and volume (L) are known gas quantity in moles can be calculated.