So i designed a chamber that filled with NO2 Gasses and N2 Gasses  
 Gases were designed to flow exact amount of 100cc/min from the gas barrel  .
They mixed up with mix valve in front of mass flow meter.

So i added  environment pressure at the outlet holes.

and i added inlet volume flow with Value 0.0001 m^3/s (uniform)

and the Substance Concentrations was N2 gas were 0.5 and NO2 Gasses were 0

The Problem is that i have no idea for the value that i input correctly .

Following the conditions will there be any problems ?

Sorry for bad english .