Amonut of air in HVAC

How many percentage of air recirculate in hvac?

It depends upon the extent of air contamination and return air filters efficiency.
In general 10%of return can be used…

Generally in non-sterile products manufacturing areas the HVAC system should provide 10% fresh air supply and remaining re-circulated air. The number of air changes can be 20 per hour.

Tq sir . Sir I have one question again, what is the microns size for pre filter and bag filter in HVAC?

Sir can you tell me, what is the main difference between AHU & HVAC?

The broader difference between AHU and HVAC systems is as follows, (However these terms are interchangeable)

AHU- Air Handling Unit. This covers simple air ventilation systems having filters ranging from 5 to 25 microns porosity, like 5, 10, 15, 20, 25 microns without HEPA filtered air supply. And also, AHU with HEPA filtered air supply system.

HVAC- Heating Ventilation and Air Conditioning system. This covers the air ventilation system with prefilters (5 to 20 microns porosity) and HEPA filters (0.3 micron) system to provide HEPA filtered air. HEPA filters are either at the terminal position in the Clean Rooms or at the Plenum position in the HVAC units.