Hi Everyone, I am trying to understand how a certain flow conversion factor was reached. The factor is used to convert Oxygen to Air and vice versa. The source of this conversion factor states: "The theoretical ratio of Air flow to Oxygen flow is as follows: (Flow (Air))/(Flow (O_2 ) )=1.0512 1.0512= √(32/28.96) Where.... Molecular Weight of O_2 = 32.00 g/mol Molecular Weight of Air = 28.96 g/mol" Based off of the Ideal Gas Law it makes sense that the ratio of flows would be based off of the ratios of molecular weights. I am not sure where the square root term comes in though? Some further information: I am measuring the flow rate through an orifice using air and now I am trying to find what the equivalent flow rate in oxygen would be. My temperature is the same for both gases, specified at 70°F. My upstream pressure is 69.7 psia and my downstream pressure is 14.7 psia. I am trying to find flow rate in LPM with a specified Temp and Pressure.