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Cleanroom Glossary

  • 2024-02-03
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The process of an adsorbate (molecules, biomolecules, ions, or atoms) adhering to and accumulating on the surface of a substance. The adsorbent can be a liquid, gas, or a solid with dissolved surface molecules.

Air filter

A device used to remove airborne contaminants. Most cleanroom air filters are comprised of fibers that are designed to capture particulates like dust, bacteria, pollen, chemicals, and mold spores through adsorption, straining, absorption, or static electric charge.

Air Lock

A dedicated space that facilitates the movement of objects or people between vessels or rooms of varying pressures. The air lock provides a space that is sealed by two airtight doors that are opened and closed successively to prevent the mixing of different gases or the alteration of pressures.

Air Shower

A specialized chamber that utilizes forced air to remove any particulate matter from a person or object before accessing a cleanroom facility. In order to minimize contamination, a cleanroom air shower often uses an air filter to capture any dust, bacterial, pollen, or mold that may be present on the surface of a person or object.

Air Velocity

The rate of air movement measured in distance traveled relative to time elapsed. Air velocity is commonly measured in meters per second (m/s) or feet per minute (ft/min).


Stream of air as it passes over the surface of a moving object or within a wind tunnel where air may move over the surface of a stationary object.

Airflow Uniformity

The consistency of which a stream of air passes over the surface of an object. Measured in volume occupied relative to time elapsed. Common airflow uniformity is measured in cubic meters per second (m³/s), liters per second (L/s), or cubic feet per minute (ft³/min).


Commonly used acronym for Air Conditioning, Refrigeration, & Building Services. ARBS refers to a large trade event that is held every two years for heating, ventilation, air conditioning, refrigeration, and other building related industries.


Commonly used acronym for the American Society of Heating, Refrigerating, and Air-Conditioning Engineers. This international organization has a mission to advance the HVAC & R (heating, ventilation, air-conditioning, and refrigeration) industries to better serve humanity and promote sustainability. ASHRAE accomplishes their mission through research and continuing education programs as well as through the writing and publishing of industry standards and a variety of other resources.

Bio Safety Hood Classification

Classification used to determine the levels of containment a fume hood will provide in regards to potential contamination by hazardous vapors, gases, and particles.

Class 1 - 100,000 Cleanrooms

Classification levels that indicate the acceptable number of particles  in a cubic foot of cleanroom space. Class levels are generally determined from the number of 0.5 micron or larger particles per cubic foot.


A designated space that is closely controlled for compliance to limitations that have been outlined for operating procedures, air cleanliness, air pressure, temperature, relative humidity, and air flow patterns. A number of devices and procedures are often used in a cleanroom to monitor the viability of airborne particles.

Cleanroom Apparel/Garments/Clothing

Non-shedding apparel that is designed specifically to serve as a barrier between cleanroom environments and possible contaminants released by cleanroom workers. Cleanroom garments may include footwear, shoe covers, coveralls, gowns, smocks, gloves, face masks, and head coverings.

Cleanroom Classifications

Classification system used to determine the acceptable concentration of particles in an identified volume of air given specific particle size parameters. Classification levels are determined by the federal government. 

Cleanroom Construction

A space or system of spaces in which there are tightly controlled limits that govern air flow, air pressure, air filtration, temperature, relative humidity, viability of airborne particles, access, and operating procedures.

Cleanroom Dispensers

Furnishings that are designed specifically for convenient dispensing of cleanroom-safe products. Cleanroom dispensers can be used for a variety of products.

Cleanroom Facility - As Built

Cleanroom facility that is prepared for operation in terms of construction and systems but without staff present or manufacturing equipment in place.

Cleanroom Facility - At Rest

Cleanroom facility that is fully equipped for operation with the exception of staff on site.

Cleanroom Facility - In Operation

Cleanroom facility that is equipped and staffed for full operations, with all staff, equipment, and supplies present.

Cleanroom Paint

Water based acrylic epoxy paint for cleanrooms that provides a durable and stain resistant finish for all cleanroom walls, ceiling, and floors.

Contained Space

Area that provides full enclosure with controlled ventilation systems and regulated access.


The utilization of filters and controlled ventilation systems in a designated space for capturing and containing potential contaminants.


A sealable enclosure that contains desiccants or nitrogen gas that are used to prevent reactions between moisture-sensitive materials and atmospheric humidity.

Electrostatic Discharge (ESD)

The transfer of electric charge between two surfaces as a result of friction.

Federal Standard 209E

Government imposed standards for air quality in a cleanroom. The standards designate classes of cleanrooms and clean zones based on the size and concentration of particles of in a given volume of air.

Fume Hoods

Cabinet that has in air flow thus protecting operator from dangerous or noxious vapors or particles.


Controlled enclosure that incorporates sealed gloves into the design, allowing for manual control of items and materials that must remain in a restricted environment.

Hardwall Cleanroom

Prefabricated room that has rigid walls and constructed to meet stringent cleanroom requirements. Hardwall cleanrooms may be incorporated into existing structures or may stand alone. Can be single pass or re-circulating air. Hardwall cleanrooms can sustain posivite pressure.  Can be ISO 3-8.

HEPA Filter

A High Efficiency Particulate Air (HEPA) filter that meet specific regulations for interception, impaction, and diffusion of airborne particulates.

HEPA Filter High Capacity

High Efficiency Particulate Air (HEPA) filter constructed to withstand high airflow levels. Measurements are estimated at 944 L/s at 350 Pa initial resistance.

HEPA Filter Module

High Efficiency Particulate Air (HEPA) filter that is integrated into a disposable housing for use in cleanroom ceiling installations HEPA filter modules are usually available in fan-assisted and non-fan-assisted variations.

HEPA High Temperature

High Efficiency Particulate Air (HEPA) filter that is constructed using materials that can withstand temperatures up to 400°C, providing filtration for cleanroom and laboratory ovens. High temperature filters use stainless steel or aluminum for the frame and silicone or glass for the gasket.

ISO Cleanroom Classifications

Cleanroom air cleanliness classifications that provide standards for the identification, control, and monitoring of various airborne particles and contaminants.

Laminar Air Flow

Air stream that flows through a HEPA filter and moves with uniform velocity within a confined space. Alternately referred to as “unidirectional flow”, laminar air flow generally moves along parallel flow lines.


Unit of measurement for miniscule length equal to one-millionth of a meter or 0.00003937 inch. Expressed as µm and alternately referred to as a micrometer.

Modular Cleanroom

Versatile engineered and pre-fabricated cleanroom units that are fitted with self-contained ventilation and electrical systems that comply with industry standards. Modular cleanrooms can be designed to accommodate a variety of size and design constraints.

Multi-pocket Filter

Extended surface air filter that organizes the filter material in a series of pockets. The number and thickness of the filtration pockets may vary depending on the application.

Panel Filter

Single or double layer filter that is either disposable or can be modified with replaceable filtration material. Most panel filters have a shallow profile with a thickness between 25-100 mm.

Particle Counter

Device that measures the size and quantity of particles per cubic air volume.  Used to determine the cleanliness rating of a cleanroom.


Miniscule segments of manmade or natural matter that has been suspended in gas or liquid.


Enclosed space with doors that is designed as an air lock to accommodate the transfer of materials between two spaces while limiting the transfer of contaminants or limiting significant changes in environmental conditions. Cleanroom pass throughs can be wall mounted or floor mounted.


Specialized filter that is designed to work with a downstream filter to guard against contamination from large dust particles.

Softwall Cleanroom

Modular structure typically consisting of either a painted steel or aluminum frame with flexible, clear curtains for walls. Softwall cleanrooms can have a cleanliness rating from a class 100,000 to a class 10 environment.  Air flows out of a space between the floor and bottom of the curtain. Standard design of flexible curtains does not permit much in the way of a measurable positive pressure to be created. 

Stainless Steel

Stainless steels are iron-based alloys containing 10.5% or more chromium. They have been used for many industrial, architectural, chemical, and consumer applications for over a half century. Currently there are being marketed a number of stainless steels originally recognized by the American Iron and Steel Institute (AISI) as standard alloys. Also commercially available are proprietary stainless steels with special characteristics. For moore information and diffrent uses, see our chart "Where Different Grades Are Used".

Sterile Air

Dedicated air supply that has been filtered to remove bacteria, viruses, yeasts, molds, and other microbiological organisms.

Sticky Mat

Floor mats which remove contaminates from shoes or wheels as they contact its sticky surface.  Sticky mats come in a permanent washable option or as disposable peel-off mats consisting of multiple layers of tacky plastic film which are peeled off as they get dirty. Available in multiple sizes and colors.

Tacky Mat

See Sticky Mat.


Air tight voice communication device that can be mounted on a number of surfaces, including glass, plastic, Plexiglas, wood, and many other wall materials. Sound is transferred through a thin Mylar diaphragm, while visual communication is achieved through a small talk thru window. A sealed plastic frame is mounted on both sides of the cleanroom wall or window surface.


Commonly used acronym for an Ultra Low Particulate Air filter which has an efficiency rating of 99.9995 on 0.12 micron particles. Usually used to create class 10 (ISO 4) or class 1 (ISO 3) cleanrooms.

Unidirectional Flow Cleanroom / Laminar Flow Cleanroom

Air stream that flows through a HEPA filter and moves with uniform velocity within a confined space. Air flow in a unidirectional flow cleanroom generally moves along parallel flow lines.


Procedures for the monitoring and documentation of compliance to specified regulations for the design, construction and performance for a clean manufacturing facility.

Wafer Handling

Management of the environment in which silicon wafers are used for chip production. Proper wafer handling usually involves cleanroom standards for facility, apparel, and equipment.  

Wet Process Station

Free-standing station for use in labs or cleanrooms for safe and functional semiconductor processing, chemical analysis, plating, microelectronic manufacturing and other custom processing. Operates under negative pressure to protect operator from harmful vapors.  Typically customized with sinks, hot plates and numerous other components for semiconductor wafer fabrication.

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