A 1000 ft 3 storage tank is filled with natural gas at 80°F and 1 atm pressure. The tank is flushed out with nitrogen gas at 80°F and 1 atm pressure, at a constant rate of 300 cfm. The flushing...

A 1000 ft³
storage tank is filled with natural gas at 80°F and 1 atm pressure. The tank is flushed out with nitrogen gas at 80°F and 1 atm pressure, at a constant rate of 300 cfm. The flushing process is carried out at constant temperature and pressure, under conditions of perfect mixing in the tank at all times. Calculate the time required to reach a gas composition of 95% by volume nitrogen in the tank.