A standard cylinder of oxygen used in a hospital has the following characteristics at room temperature (295 K): gauge pressure = 13,800 kPa (2000 psi), volume = 16 L (0.016 m^3). How long will the cylinder last if the flow rate, measured at atmospheric pressure, is constant at 2.4 liters/min? I tried to find the volume (in liters) at atmospheric pressure. It didn't come out right. Since nRT is constant do I need to find the number of moles? Am I taking the wrong approach?