Pressure build up profile in gas container

[Arkon]

I have methane leaking into a gas container from a connected reservoir cylinder. If the volume of the container is fixed and the initial pressure is known (say atmospheric), how can I determine the leak rate from the pressure build-up versus time relationship. The pressure versus time profile seem to follow a power relationship (i.e pressure increases rapidly at initial stage and then the build-up rate decreases).

 

[Vadar2012]

Look up Bernoulli's equation. That will lead you to the flow rate, which is volume per time. I assume you mean flow rate instead of leak rate.