What is the output pressure graph in my simple Pneumatic system?

I am doing basics Pneumatics and I have a question about how one would calculate the following.
In general I hope to get an idea of how to dimension Pneumatic systems. I have done differential equations, linear algebra etc. but it has been many years since.

Given a system of a full pressure tank with air, being opened through a valve into a pipe with a leak.
How do I determine the maximum pressure, and in more general the curve of the pressure?

I can start with assuming that:

• The pipe has a neglible diameter and an infinite flowrate.
• Temperature is constant in whole system. Although it would be cool to see how one would do it with – those aswell.

I would like to account for the flowrate of the valve.

I have made the following simulation, and associated graph in FluidSIM.
I have the initial pressure in the tank at 7bar, flowrate in valve to be 60 L/min,
flowrate in leak to be 12 L/min