I need to flux 250 ppm of CO2 at 1000 ml/min.
I have a gas system with a tank containing CO2 (CO2 at 5000 ppmvol, Oxygen 21%vol and Nitrogen the rest), connected with a mass flow controller (MFC1, flux max at 150 ml/min) and I have a tank of dry synthetic air (O and N), connected with a second mass flow controller (MFC2) that can be fluxed at a max of 1000 ml/min. Since I don’t have the possibility to measure the ppm of the CO2 after the dilution, I need to know a right way to dilute the CO2 in my tank (that already contains a mix of CO2 and air).
I know that I can digit the values of 50 ml/min for MFC1 and 950 ml/min for MFC2, obtaining a final flux of 1000 ml/min. But, in this way, I don’t understand the final concentration of CO2. I don’t know if applying this formula 5000ppm*(MFC1/tot flux) [that means 5000ppm*(50ml/min : 1000 ml/min)] I am double diluting my gas (because I am considering two times the air, once mixed with the CO2 tank and the other ones in the other air tank). Or, I don’t know if this formula [5000ppm*(50ml/min : 950ml/min] is the correct one, since apparently I consider air in the CO2 tank and air in the other tank.
I don’t even know if my approach to this problem is wrong and both formulas are not correct (e.g. I should consider other parameters; the carbon dioxide is a pollutant and so it follows particular rules/formula/conversion).