Air shower (room)

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Cleanroom air shower with a blue sticky floor mat for shoe sole cleaning. Cleanroom air shower.jpg
Cleanroom air shower with a blue sticky floor mat for shoe sole cleaning.

Air showers are specialized enclosed antechambers which are incorporated as entryways of cleanrooms and other controlled environments to reduce particle contamination. [1] Air showers utilize high-pressure, HEPA- or ULPA-filtered air to remove dust, fibrous lint and other contaminants from personnel or object surfaces. The forceful "cleansing" of surfaces before entering clean environments reduces the number of airborne particulates introduced. [1] [2]

Contents

When properly incorporated into cleanroom design, air showers provide an ISO-classified transition vestibule to ensure the cleanliness of the classified cleanroom. Air showers are typically placed between a gowning area and cleanroom; after workers don appropriate garb and personal protective equipment, they enter the shower so that the pressurized air nozzles remove any residual particles from coveralls. Once the program cycle is complete, users exit through a second door into the cleanroom. Air showers (or air tunnels) may also be placed between cleanrooms of different ISO ratings. [2]

Design and functionality

Air showers are generally constructed from cleanroom-compatible steel or plastic materials and feature electronically-powered blowers, filters and high-pressure jet nozzles, the latter being incorporated into the walls and ceiling of the chamber. [3] Air, at velocities of 3,000 ft/min (15 m/s) to 7,000 ft/min (36 m/s), continuously streams from the jet nozzles for 30–45 seconds, effectively removing loose particulate matter. [4] Personnel inside the enclosure will lift their arms and turn their bodies for uniform exposure to the air streams, a procedure usually specified in protocol. Air currents from the jets create shearing and flapping forces, which lift and remove contaminants from both flat surfaces and the creases of garments. [4] HEPA filtration within the air shower is capable of removing 99.97% of particles greater than 0.3 µm diameter. [5]

Air is channeled within the air shower using a closed-loop system, where it is continuously re-circulated. Air is forced through a motorized filter/blower module into a large plenum, then into the shower through jet nozzles. Particle-laden, contaminated air is routed out of the shower compartment through floor vents and returned to the filtration unit. This process ensures that only decontaminated air is used to remove particulates from personnel and other equipment, such as supply carts.

Often, air showers are equipped with air ionizers to reduce static electricity, as large volumes of high-velocity air create electric charges. Since laboratory equipment, electronic measuring instruments and many hi-tech manufactured goods can often be damaged by electrostatic discharge, ionizers are essential in rendering material surfaces electrically neutral before entering the cleanroom. [2]

Safety

Interlocking mechanisms are a common air shower feature to prevent both exits from being opened simultaneously, which would allow outside air to enter a tightly controlled environment. This requires occupants to stay inside until the decontamination cycle has been completed. For this reason, safety features such as emergency stops are required by most safety administrations. Alternatively, the air shower may consist of a long tunnel not equipped with doors. Personnel slowly walk through to reach the controlled area. [2] Air handling equipment creates an isolated atmosphere using pressure differentials to create fluid boundaries between the inner and outer environments.

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<span class="mw-page-title-main">Radioactive contamination</span> Undesirable radioactive elements on surfaces or in gases, liquids, or solids

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<span class="mw-page-title-main">HEPA</span> Efficiency standard of air filters

HEPA filter, also known as high-efficiency particulate absorbing filter and high-efficiency particulate arrestance filter, is an efficiency standard of air filters.

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<span class="mw-page-title-main">Air purifier</span> Device that removes contaminants from the air in a room

An air purifier or air cleaner is a device which removes contaminants from the air in a room to improve indoor air quality. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke.

<span class="mw-page-title-main">Air filter</span> Device composed of fibrous or porous materials which removes solid particulates from the air

A particulate air filter is a device composed of fibrous, or porous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbon) may also remove odors and gaseous pollutants such as volatile organic compounds or ozone. Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines.

Ultra-low particulate air (ULPA) is a type of filter. A ULPA filter can remove from the air at least 99.999% of dust, pollen, mold, bacteria and any airborne particles with a minimum particle penetration size of 120 nanometres. A ULPA filter can remove—to a large extent but not 100%—oil smoke, tobacco smoke, rosin smoke, smog, and insecticide dust. It can also remove carbon black to some extent. Some fan filter units incorporate ULPA filters. The EN 1822 and ISO 29463 standards may be used to rate ULPA filters.

<span class="mw-page-title-main">Dust collector</span>

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A particle counter is used for monitoring and diagnosing particle contamination within specific clean media, including air, water and chemicals. Particle counters are used in a variety of applications in support of clean manufacturing practices, industries include: electronic components and assemblies, pharmaceutical drug products and medical devices, and industrial technologies such as oil and gas.

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The Institute of Environmental Sciences and Technology (IEST) is a non-profit, technical society where professionals who impact controlled environments connect, gain knowledge, receive advice, and work together to create industry best practices. The organization uniquely serves environmental test engineers, qualification engineers, cleanroom professionals, those who work in product testing and evaluation, and others who work across a variety of industries, including: acoustics, aerospace, automotive, biotechnology/bioscience, climatics, cleanroom operations/design/equipment/certification, dynamics, filtration, food processing, HVAC design, medical devices, nanotechnology, pharmaceutical, semiconductors/microelectronics, and shock/vibration. Information on ISO 14644 and ISO 14698 standards can be found through this organization.

<span class="mw-page-title-main">Contamination control</span> Activities aiming to reduce contamination

Contamination control is the generic term for all activities aiming to control the existence, growth and proliferation of contamination in certain areas. Contamination control may refer to the atmosphere as well as to surfaces, to particulate matter as well as to microbes and to contamination prevention as well as to decontamination.

<span class="mw-page-title-main">Biosafety cabinet</span> Type of laboratory equipment

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<span class="mw-page-title-main">Air purge system</span> Type of automatic cleaning for electrical systems

An air purge system is used to flush electrical control equipment with clean air before it is turned on. This ensures that the functionality of the equipment is not affected or damaged by the contaminants from the surrounding environment.

<span class="mw-page-title-main">Clean air delivery rate</span> Filtration efficacy measurement

The clean air delivery rate (CADR) is a figure of merit that is the cubic feet per minute (CFM) of air that has had all the particles of a given size distribution removed. For air filters that have air flowing through them, it is the fraction of particles that have been removed from the air, multiplied by the air flow rate through the device. More precisely, it is the CFM of air in a 1,008-cubic-foot (28.5 m3) room that has had all the particles of a given size distribution removed from the air, over and above the rate at which the particles are naturally falling out of the air. Different filters have different abilities to remove different particle distributions, so three CADR's for a given device are typically measured: smoke, pollen, and dust. By combining the amount of airflow and particle removal efficiency, consumers are less likely to be misled by a high efficiency filter that is filtering a small amount of air, or by a high volume of air that is not being filtered very well.

<span class="mw-page-title-main">Fan filter unit</span>

A fan filter unit (FFU) is a type of motorized air filtering equipment. It is used to supply purified air to cleanrooms, laboratories, medical facilities or microenvironments by removing harmful airborne particles from recirculating air. The units are installed within the system's ceiling or floor grid. Large cleanrooms require a proportionally large number of FFUs, which in some cases may range from several hundred to several thousand. Units often contain their own pre-filter, HEPA filter and internally controllable fan air distribution.

Dry decontamination is a method of removing contaminants without the need to use water or other liquids. Decontamination is an essential duty of hazmat responders as it protects victims from harmful reactions to the contaminants.

<span class="mw-page-title-main">Sticky mat</span>

A sticky mat, also called a tacky mat or cleanroom mat, is a mat with an adhesive surface that is placed at the entrances or exits to certain workplaces to remove contaminants from the bottoms of footwear and wheeled carts such as hand trucks. They are an example of an engineering control within the hierarchy of hazard controls.

<span class="mw-page-title-main">Hazmat diving</span> Underwater diving in a known hazardous materials environment

Hazmat diving is underwater diving in a known hazardous materials environment. The environment may be contaminated by hazardous materials, the diving medium may be inherently a hazardous material, or the environment in which the diving medium is situated may include hazardous materials with a significant risk of exposure to these materials to members of the diving team. Special precautions, equipment and procedures are associated with hazmat diving so that the risk can be reduced to an acceptable level.

References

  1. 1 2 Cosgrove, Chris K. (2003-01-01). "How Do Air Showers Fit Into A Contamination Reduction Plan?". Advantage Business Media. Archived from the original on 2016-08-23. Retrieved 2016-08-22.
  2. 1 2 3 4 Welker, Roger W.; Nagarajan, R.; Newberg, Carl E. (2005-10-04). Contamination and ESD Control in High Technology Manufacturing. Hoboken, New Jersey: John Wiley & Sons. ISBN   978-0-471-41452-0.
  3. Loughran, Timothy M.; Shea, Michael J. (2015-02-16). The Effectiveness of Air Showers in the Contamination Control Process. Archived from the original on 2016-12-20. Retrieved 2016-11-15.
  4. 1 2 Ottney, Thomas C (1996-09-01). "Air Showers Reduce Lint Defects". Metal Finishing. 97 (5): 402–406. doi:10.1016/S0026-0576(00)80440-7.
  5. ASME AG-1a-2004: addenda to ASME AG-1-2003, Code on Nuclear Air and Gas Treatment. American Society of Mechanical Engineers. 2004.