I am a mechanical engineer and need some help in calculation... We have a Nitrogen gas generator producing 240 Nm3/hr of gas, this gas is supplied to a buffer tank of 20 m3 capacity, after this buffer tank the n2 gas is supplied 2 Dry gas sealing systems requiring total 192 Nm3/hr flow rate at 6.5 bar to 4.5 bar lowest. Should the N2 Generator fail, how long can the buffer tank back-up (minutes) the supply till pressure drop to 4.5 bar? I did the basic t= V(p1-p2)/flow rate, but i doubt the answer. I need help in calculating this,.. Thanks in advance.