Hi,
I understand that loading rate is 80 m3/h = outbreathing rate, what about the unloading rate =inbreathing rate?
You need to make sure your vent line is big enough to avoid overpressure during the tank feeding and vacuum during the unloading.
I suppose your tank is designed for low pressure.
To accommodate a low-pressure tank, you must calculate the vent diameter using the equation provided in my spreadsheet. This calculation requires knowledge of the pipe length, the head losses associated with fittings (such as contraction from tank to vent, discharge to atmosphere, etc.), and the temperature inside the tank to determine air viscosity and density. The pressure inside the tank, P1, equals the external pressure P2 or atmospherical pressure plus the head loss in the vent.
Assume a pipe diameter that results in a 10-mbar head loss in the vent line, and then calculate the flow rate.
You check that the flowrate is compatible with both in breathing and out breathing flow rate. If not iterate with another pipe diameter. As a general guideline, the diameter should be a minimum of 3 to 4 inches. Additionally, the area of the discharge slots must equal the area of the vent pipe.
Good luck
Breizh