Calculating pressure drop across filter units
 

I am a mechanical engineer and my company is in the middle of finalizing a software for air flow modeling and analysis. We are manufacturers of inline filter units for HVAC systems. The software should be able to find the pressure drop across the filter units and also the amount of airflow required for each zone and stuff like that. I have been going through different software to meet these requirements and they are CONTAM, AIRPAK, etc.

I would really like the inputs from everyone as to what you guys think might be suitable for us.