FAQs About Clean Benches

What is a clean bench?

A clean bench is a workstation that provides a localized ISO Class 5 (Class 100) clean air environment at the work surface using HEPA-filtered laminar airflow. Clean benches are used for tasks requiring a high-cleanliness work environment without the need for a full room-sized cleanroom — such as assembling sensitive electronic components, preparing pharmaceutical compounds for compounding pharmacies, handling optical elements, or conducting research requiring a particle-controlled workspace. Clean Air Products manufactures clean benches as part of its ISO-compliant cleanroom product line.

What is the difference between a horizontal and vertical flow clean bench?

The difference between horizontal and vertical flow hoods can be seen in the design of each system. Horizontal airflow is generally best when the workpiece has a large horizontal surface and/or a narrow cross-section perpendicular to the airflow. Horizontal airflow is also well suited for applications in which an individual must work directly over the workpiece. In a horizontal flow clean bench, there is constant clean airflow between the work object and the worker's hands or instruments. A typical horizontal laminar flow workstation has a tabletop and a three-sided hood. The HEPA filter is located on the vertical rear side of the work surface and is susceptible to damage. A secondary grill is sometimes needed for filter protection.

Vertical flow is used for a number of reasons, but the size and type of object are the primary considerations. Large objects can block the airflow in a horizontal laminar flow workstation, creating large areas of turbulence on the downstream side of the object. These turbulent areas often become contaminated as ambient air is drawn in. With vertical flow, air enters the work zone from the top and flows downward, surrounding the object within the work area. Air flows on the front, sides, and rear, bathing the object on all sides with clean, filtered air. The vertical flow option should not be chosen if an operator is leaning over the work that is being done in the clean bench.