What Does Air Change Rate (ACR)Mean in Air Filtration?

Air Change Rate (ACR) is the rate that the entire volume of air in a given space is replaced with supply and/or recirculated air.

It is widely expressed and the as the number of Air Changes per Hour (ACH or ACPH), or Volumes per Hour,

indicating the number of time the room’s volume has been replaced/ recirculated in one hour.