The Effectiveness Of Air Shower And Air Filtration
Effectiveness — power and capacity
Power and capacity are the major influences on the effectiveness of an air shower. Cleaning power is determined by nozzle velocity: the speed at which air is pushed through the nozzles. It takes highvelocity air to dislodgecontaminants; the higher the velocity or cleaning force, the more contaminants are removed.
Capacity is the volume of air circulated in the system. More air volume means faster cleaning and removal of contamination through the filtration and recirculation system.
To specify the most effective air shower, look for one that produces nozzle velocities of 7,800 feet per minute (fpm) and circulates 1,900 cubic feet per minute (cfm) of air.
Velocity is measured at the nozzle, and cleaning effectiveness deteriorates as distance from the nozzle increases. Therefore, air showers should have a high number of air nozzles positioned as close to the worker or product as possible. Ideally these nozzles should be positionable as well as removable to allow for easy inspection of the high-pressure supply ducts.
An air shower’s recirculating air filtration systems typically use two sets of filters. The first is a pre-filter for catching the bulk of contaminants. The second is a highcapacity, 99.97%-efficient HEPA filter.
System blower units are usually mounted in the ceiling. If your facility has height restrictions, make sure the blowers can be mounted on the external wall.
For easy routine maintenance, pre-filters should be changed regularly. Replacement filters are economical and easy to change.