How can I calculate the volume of leaked gas in a leak testing project?

[OffshoreEng]

Hi,
I am working on a leak testing project in which i have a leaking valve and I am trying to determine the volume of nitrogen leaking through the valve.

Side A (upstream of valve) starts at 4000psi with an unknown volume. Side B (downstream of valve) starts at 0psi with a pressure contained volume of 100ft^3. After 1 hour, Side B now has 4psi. How can I calculate the volume of air that leaked through the valve from Side A to Side B?

I have attached a visual for a better understanding.

Thank you for your help.

 

[SteamKing]

You've got a fixed volume with a certain pressure inside. By making a reasonable assumption about the temperature of the gas inside, you can use the ideal gas law to calculate the mass of air (nitrogen?) which has leaked into Side B.