What you need to know. Class I & II biological safety cabinets

Class I Biological Safety Cabinets

The Class I cabinet has the simplest design of all Biological Safety Cabinets available. A flow of air drawn via an aperture at the front face of the Safety Cabinet ensures the safe containment of aerosols brought about during microbiological handling. The contaminated air then makes its way into a filtration system before it is safely exhausted from the enclosure. Monmouth offer multiple configurations, both Ducted and Non-Ducted that include HEPA (High Efficiency Particulate Air) and Activated Carbon Filters within our Guardian® Biological Safety Cabinet range that ensure safety across a wide variety of applications.

All Class I biological safety cabinets are suitable for work with microbiological agents assigned to biosafety levels 1, 2 and 3.

Class II Biological Safety Cabinets

Like Class I safety cabinets, Class II cabinets have a flow of air drawn via the front aperture into the cabinet. This is known as the inflow and it prevents the aerosol generated during microbiological processes from escaping through the front opening.
However, unlike Class I cabinets, the inflow air on Class II cabinets flows into an inlet grille, which is situated at the front edge of the worksurface. None of the contaminated air enters the working enclosure of the cabinet, which means the sample being manipulated is safe from contamination.

Class II cabinets also feature a vertical flow of HEPA filtered air that cascades unidirectionally from the front face of the cabinet. This is known as the downflow. This creates an air curtain while continually flushing the enclosure of airborne particles and therefore ensuring the working sample is protected from contamination.

The multitude of Class II cabinets available are primarily distinguished by the proportion of exhausted air to that of air re-circulated from the safety cabinets outlet exhaust. The Monmouth Guardian® is a Class II Type A2 biological safety cabinet which is the most common of all variations available. In this system, 30% of the air is exhausted, and the other 70% is re-circulated to the work area to form the unidirectional downflow. Monmouth offer an anti-blowback valve to allow the exhausted air to be ducted to atmosphere if so required. Another option allows light chemical use within the safety cabinet. The 30% exhaust air is channelled via a rear plenum and directed to an undermounted Carbon Filter Box option as pictured.

All Class II biological safety cabinets are suitable for work with microbiological agents assigned to biosafety levels 1, 2 and 3.