What is a cleanroom?
A cleanroom is a specially designed and controlled environment in which the concentration of airborne particles is regulated to meet a specified cleanliness standard. Cleanrooms use filtered air supply, controlled airflow patterns, positive or negative pressure, and strict protocols to minimize contamination. They are used in manufacturing, research, and processing applications where airborne particles could damage or contaminate sensitive products such as circuit boards, medical devices, pharmaceuticals, and mechanical components.
What is the difference between a modular cleanroom and a conventional (stick-built) cleanroom?
A conventional cleanroom is built into the permanent structure of a building using traditional construction methods — it is permanent, expensive to build, and difficult to reconfigure. A modular cleanroom uses pre-engineered, demountable panels and components that can be assembled on-site in days or weeks rather than months. Modular cleanrooms offer significant advantages: they are easily reconfigurable, relocatable, and expandable; require no permanent structural modifications; have faster lead times and lower installation costs; and cause minimal disruption to surrounding operations during installation. Clean Air Products specializes in
modular cleanroom systems, including
softwall configurations.
What are the key design factors to consider when specifying a cleanroom?
The four key factors when designing a cleanroom include:
(1)
ISO Classification — the required cleanliness level determines the air filtration, airflow volume, and room construction requirements
(2) Application and Product — the sensitivity of the product or process being protected and any special requirements (anti-static, temperature/humidity control, sterility)
(3) Size and Layout — the dimensions, number of personnel, equipment placement, and workflow
(4) Recirculating vs. Non-Recirculating — whether the cleanroom recirculates filtered air internally or exhausts and replaces it.
Clean Air Products provides a detailed design considerations guide on our website.
What is HEPA filtration and why is it used in cleanrooms?
HEPA (High Efficiency Particulate Air) filtration is the industry standard for cleanroom air filtration. A HEPA filter is rated to capture 99.97% of particles at 0.3 microns — the most penetrating particle size. HEPA filters are used in cleanroom ceilings (in
fan filter units),
air showers,
clean benches, and
pass-throughs to provide the ultra-clean air supply required to maintain
ISO cleanliness standards. ULPA (Ultra Low Penetration Air) filters offer even higher efficiency (99.9995% at 0.12 microns) for the most demanding applications such as ISO Class 1-3.
What is laminar flow and why does it matter in cleanrooms?
Laminar flow (also called unidirectional flow) is a controlled, uniform airflow pattern in which all air moves in a single direction at a consistent velocity — typically from ceiling to floor (vertical laminar flow) or from one wall to the opposite wall (horizontal laminar flow). Laminar flow prevents turbulence that could stir up and redistribute particles, ensuring that any contaminants generated within the room are swept away from the product or work surface and exhausted from the cleanroom. Fan filter units and
clean benches use laminar flow to protect products and processes from contamination.
What is positive pressure vs. negative pressure in a cleanroom?
A positive pressure cleanroom is maintained at a slightly higher air pressure than the surrounding environment. This means air flows outward through any gaps or openings, preventing unfiltered outside air from entering the cleanroom — protecting the product from contamination. Positive pressure is standard for most cleanrooms in
electronics, medical devices, and
life sciences. A negative pressure cleanroom is maintained at lower pressure than the surrounding area, so air flows inward. This is used in containment applications — such as pharmaceutical manufacturing of hazardous compounds or infectious disease research — where the goal is to prevent contaminated air from escaping the cleanroom.
What is the difference between recirculating and non-recirculating cleanrooms?
A recirculating cleanroom re-filters and recirculates the room air continuously through HEPA filters, maintaining cleanliness without exhausting all the conditioned air. This is more energy-efficient and easier to maintain temperature and humidity control. A non-recirculating (once-through) cleanroom exhausts all of its supply air and replaces it with 100% outside air that has been filtered and conditioned. Non-recirculating designs are typically used in containment or hazardous material applications where recirculating the air would be unsafe. Clean Air Products designs and manufactures both recirculating and non-recirculating
modular cleanrooms.
