I have a work related question. Although it seems like a relatively simple question, I am having difficulties finding the correct equation(s) to calculate the answer. Question: Given a fixed volume air tank filled with pressurized air, how does one calculate the flow rate over time through an orifice of known size? An example flow rate calculation at maximum pressure would be appreciated. Where: Air tank volume is 3.277 cubic liters = 0.003277413 cubic meters Orifice diameter = 0.0013208 m Air pressure max P1 = 1073.485776 kpa abs Air pressure min P2 = 101.325 kpa abs Max time for pressure drop from P1 to P2 = 60 sec R = gas constant of air = 287 J/kg K = 0.287 kJ.m3/kgK air density –ρ = 1.225 kg/m3 *Temperature = 20C *For now, the temperature is assumed to be fixed at 20C even though there will be a reduction in temperature resulting from the reduction in pressure.