Supposing you had a cylindrical closed tank inside the body of a submarine; the top of the tank is at 200m depth. The tank has height 2.5m and internal volume 1.8m^3. A section of pipework is connected between the top surface of the submersible (level with the top of the tank) and to the tank (assume inlet is at the bottom of the tank); an orifice plate will control the incoming flow rate. A separate pipe connects to the side of the tank, through which air will be supplied at a constant pressure of 30 bar; with volumetric flow rate 5.7m^3/min (if required). Assuming the initial pressure inside the closed tank is normal atmospheric (1 bar), how would you calculate the time for the pressure of the air bubble in the top of the tank to equalise with the pressure external to the top of the tank at 200m? Ignore frictional losses in the pipeworks.