Thu May 19, 2022
Air shower size
Air showers are designed to quickly and effectively remove particulate prior to entering a cleanroom. The air shower selection criteria allow for high air-flow volume combined with high nozzle velocity, providing optimal operational power and force.
Air showers are self-contained air recirculation systems installed at entrances to cleanrooms and other controlled environments. Since people and products are the main sources of cleanroom contamination, these cleanroom entry systems quickly and efficiently remove particulate contaminants from workers or products before they enter a clean space.
Air showers operate similarly to automated car wash pressure washer systems, utilizing multiple steps throughout the decontamination process. The following cleanroom air shower specifications process details the operational aspects of a cleanroom air shower.
Additionally, it takes four to eight seconds of cleaning time and another two to four seconds for the air shower to purge contaminated air before the worker can exit. Computerized microprocessors control the cleaning and wait times associated with the air shower decontamination process.
Air showers are the final cleaning step before entering a cleanroom. Prior to entering the air shower, workers put on appropriate cleanroom clothing in a gowning room—either a suit (which covers nearly the entire body) or a gown and cap or hood. Since people are the main source of cleanroom contamination, workers must follow a series of procedures before entering a cleanroom.
This “gowning” process disturbs and releases contaminants from street clothes that can settle onto cleanroom garments. Air showers remove the contaminants. This procedure helps to maintain cleanroom standards and helps to lower operating costs. This procedure helps to maintain cleanroom standards and helps to lower operating costs. The decontamination procedure in the air shower means cleaner air enters the cleanroom, reducing product defects and increasing production yields.
Air showers blow high-velocity jets of HEPA-filtered air to remove loose particles from people and products before they enter a cleanroom. This decontamination process means cleaner air enters the cleanroom, reducing product defects and increasing production yields. Additional advantages include longer-lasting cleanroom HEPA (high efficiency particulate air) filters because contaminant loads are lower. The pre-cleaning air shower process also reduces the contamination load of the main cleanroom filtration system, reducing energy consumption and maintenance costs.
Whether the goal is high semiconductor yields or a flawless paint finish, controlled environments are integral to manufacturing processes. Air showers are vital to maintaining the clean environment; they help protect operations from the constant threat of air particulate contamination. Some of the industries that directly benefit from proactive air shower design concepts include:
Decontamination air showers are usually used for cleaning gowned personnel before entering a clean environment. However, they are also used to remove particulates from workers as they leave hazardous work areas and mingle with the general public. Further, an exit decontamination air shower can prevent cross-contamination when moving from one workspace to another.
Important factors to consider when specifying an air shower include effectiveness (power and capacity) and air filtration.
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 high-velocity air to dislodge contaminants; the higher the velocity or cleaning force, the more contaminants are removed. Conversely, 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 able to be positioned and removed 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 high-capacity, 99%-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.