Cleanroom Air Flow
Cleanrooms are designed to have vertical filtered air flow to keep the room as particle free as possible. The HEPA Fan filter units in the ceiling push the HEPA filtered air into the room where it travels down to floor and exits via low wall air returns.
A properly designed cleanroom will have laminar (think smooth river) air flow that sweeps contamination out of the cleanroom in the most effective manner. A poorly designed cleanroom may have turbulent (think raging rapids) air flow that just pushes contamination around the room.
Cleanroom air flow – recirculating
Cleanroom air flow – one pass
Q: What is a recirculating cleanroom?
A: In a recirculating cleanroom the air passes over and over thru the HEPA fan filter units. This makes the air cleaner and cleaner as well as extending the life of the HEPA fan filter units.
Q: What are advantages of recirculating cleanroom?
A: Recirculating cleanrooms typically have their own air conditioning systems . This allows for temperature and humidity control. In a recirculating cleanroom the air passes thru the HEPA fan filter units over and over . This makes the air cleaner and cleaner as well as extending the life of the HEPA fan filter units.
Q: What are advantages of one pass cleanrooms?
A: Typically one pass cleanrooms are lower cost than recirculating cleanrooms as they do not include air conditioning.
Q: What are disadvantages of one pass cleanrooms?
A: They cannot really accommodate AC so you cannot control temperature of cleanroom. Workers inside where cleanroom suits can get very hot. Also One pass cleanrooms draw outside unfiltered air thru the HEPA fan filter units so they typically cannot achieve same level of cleanliness as recirculating rooms. Finally the HEPA fan filter units have significantly shorter life in one pass cleanrooms as they are constantly drawing dirt from the outside into the filter.
Q: What is a softwall cleanroom?
A: Softwall cleanroom use clear vinyl curtains to form the walls of the cleanroom. They are almost always designed as one pass cleanrooms. The air exhausts underneath the curtain at the floor level to outside of cleanroom.