Class II A/B differs in the proportion of air exhausted and re-circulated within the cabinet; velocity of airflow to the work zone creates an ultra-clean environment for product protection. An air barrier between the operator and the work zone is maintained by a flow of room air into a full width grille in the work opening. The barrier air mixes with the laminar air in a sump underneath the work surface, and is re-circulated with in the cabinet through HEPA filter.
Class II A/B Biohazard Safety Cabinets are not recommended for use with gases or vapors. A primary application is for sterile packaging. Care is required while decontaminating the cabinet.