What is the volume in liters?

What would be the pressure of the gas inside an air-tight box of volume 145 liters?

• I have a box of volume 150 liters. I want to keep the inside oxygen concentration of 75% which is maintained through a very sophisticated regulator and sensor connected directly to an oxygen cylinder. This regulator is capable of maintaining oxygen concentration within an acceptable range of 75% plus minus 0.5%. With this air-tigh box, I managed to reach a concentration of the gas to 75% with a gas volume of roughly 199 liters (Since this box is to some extent air-tight, though there might be some micro holes which I cant see with naked eye). I assume with this volume of gas (199 liters, more than the volume of the box), there would be a build up of pressure inside the box. I want to know as to what would be the pressure inside the box? where the dimensions of the box are 79.6 cm x 58.2 cm x 44 cm? Please also include the formula in your answer. Secondly, if I want to renew the gas volume at a rate of 500 ml/hour, what should be the diameter of an exit hole in the box? Thanks. Please don't hesitate to ask more details if you need. Thanks

• Answer:

  1] PV = nRT 2] I suggest that you put a rotometer on the exit, drilling a hole in the box to feed it. 3] Be vary careful with the extreme fire hazard involved.