Glossary of Common Cleanroom Terminology

Glossary of Common Cleanroom Terminology

Cleanroom – A room, enclosure, or any other environment where contaminants are controlled within specified limits. Air is directed through the room to control the airborne particle levels and in some cases temperature and humidity. The level of contamination control separates one class of cleanrooms from another.

Class 1 – 100,000 Cleanrooms – A cleanroom class category is defined by the number of microns found in a cubic foot of air. The classes represent the number of microns found in one cubic foot of air. For example a Class 1,000 room can have up to 1,000 microns per cubic foot.

  • Class 100,000 (ISO 8 / M 6.5) Basic Clean
  • Class 10,000 (ISO 7 / M 5.5)
  • Class 1,000 (ISO 6 / M4.5)
  • Class 100 (ISO 5 / M 3.5)
  • Class 10 (ISO 4 / M 2.5)
  • Class 1 (ISO 3 / M 1.5) Extremely Clean

Air Shower – An air shower is a hallway or room leading to the entrance of a cleanroom. In an air shower, high velocity air blows off particles that could contaminate a cleanroom. Sometimes, air showers are combined with static removal equipment or HEPA filters to make the them more effective in the removal of hair and other contaminants.

Air lock – An air lock is a room attached to a cleanroom that acts as a buffer zone between the cleanroom and outside space. Its interlocking doors keep the cleanroom pressurized and particle free during the transfer of objects or personnel. Air locks are commonly used for gowning.

Air Plenum – The space between an inner and outer wall or ceiling of a cleanroom. ‘Dirty’ air is forced into the plenum and then flows through a HEPA or ULPA filter and is returned as ‘clean air’ to the inside working area of the cleanroom.

Backward Compatible – All Angstrom Technology cleanrooms are backward compatible, meaning they can be repaired or expanded with new materials that match the aesthetics and performance of the original. No purchase is ever outdated or wasted because you can improve, expand, improve cleanliness, increase classification, and upgrade discrete zones at any time.

Bio Safety Hood Classification

The Class I Biosafety cabinet is a ventilated cabinet with in inward airflow and outlet HEPA filters. It was previously referred to as the CDC Hood and served a valuable function in its time by protecting personnel and environment. Because it offers no product protection, it has been essentially obsolete for the past several decades.

Class II (Types A and B) are Laminar Flow Biological Safety Cabinets that protect personnel, product and environment. They provide inward airflow to protect personnel, downflow HEPA filtered air to the rok area to protect the product and exhaust HEPA filtered air to protect the environment from particulate and aerosol hazards.

Class III cabinet is defined as a ventilated glovebox. This is a gas-tight chamber operated through sealed gloves which provide a complete barrier between the worker and hazardous material. The glovebox is maintained under negative pressure with HEPA filtered supply air and double HEPA filtered exhaust air.

Ceiling Grid System – The prefabricated framework of interlocking bars that hold lights, filters and other ceiling components in a cleanroom is a grid system. A sealant may be used to prevent airflow around filters and lights.

Federal Standard 209E – Standard 209E are the Federal Government’s basic design and performance requirements for cleanrooms. It describes methods for class verification, cleanliness monitoring and other maintenance issues.

Flooring System – Different types of flooring are used in cleanrooms, depending on the class and level of cleanliness needed. Flooring material can be made of material that controls static, it can be perforated for laminar flow, sticky for trapping dust, or seam sealed for contamination control. Angstrom offers all of these options, and more.

Garments – Special cleanroom apparel made of synthetic fiber, such as nylon, Tyvek or Dacron that are lint-free and limit contamination from personnel.

HEPA – High Efficiency Particulate Air. HEPA Filters are used to remove 99.9% of particles as small as .3 microns.
Laminar Flow – Laminar Flow is unidirectional airflow. In a cleanroom, it is filtered air flowing vertically or horizontally with uniform velocity in a single direction. Filtered air flows through your cleanroom and back to an air return, to be re-filtered and returned to the room. Laminar flow is a major part of keeping your cleanroom contaminant free.

Micron – A micron is a millionth of a meter. To compare, a human hair is about 100 microns wide.

Particulate – Particulate is contamination in the air, or contamination generated from a process.

Pre-Filter – Pre-filters are replaceable filters that remove large contaminants from the air before it is cycled through a HEPA or ULPA filter for final purification.

Pass-thru – A pass-thru is a chamber for passing items between the cleanroom and outside room. The higher pressure in the cleanroom forces particles out when the inner door opens. Less traffic in and out of a cleanroom means fewer chances for contaminants to enter.

Recovery – The speed at which a room cleans itself and returns to normal is known as recovery.

Talk-thru – A talk-thru is a special, covered opening in the cleanroom wall that allows people outside to talk to those inside without entering the room and causing contamination. Standard membrane and electronic talk-thrus are common.

Sticky Mat – A sticky mat is a special mat at the entrance to a cleanroom with an adhesive coating that removes dirt and other particles from shoes.

Sealant – Sealant is used to seal filters, lights and other cleanroom components to prevent the spread of contaminants. Silicone, plastic and gel sealants are commonly used.

ULPA – Ultra Low Penetration Air. ULPA Filters are used to remove 99.9% of particles as small as .1 microns.

Testing and Certification – In order to be assured your cleanroom meets prescribed standards, testing and certification of the room itself, as well as major components is recommended. HEPA and ULPA filters, laminar flow equipment, ionization equipment, safety cabinets and HVAC equipment, and others, are recommended for testing annually.

As Built – A term used to describe a functioning cleanroom with no furniture, process equipment, or personnel. When inspected, it is considered ‘as built’. This level is usually tested in new rooms only and is very easy to pass.

At Rest – A term used to describe a fully operational room with furniture, process and support equipment in place but not operating with personnel. When inspected, it is considered ‘at rest’. This is the most commonly tested condition and is also easy to pass because no particles are being generated within the room by personnel.

Operational – When the cleanroom is fully furnished and staffed, it is considered operational. This is the most difficult inspection level to pass because it includes personnel, the dirtiest component of an operational cleanroom. People can shed hundreds of thousands of particulate per hour.


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