Whenever safety is concerned, it's important to be exact with standard classifications. When it comes to biological safety cabinets, there are two main classifications, and you won’t want to mix them up lest you create a hazardous situation. If you’re not sure about your cabinets, you can always hire a professional to do biosafety cabinet testing. In the meantime, these are the main points of difference between.
There are certain features common to both classes of cabinets. For instance, you can use nonvolatile chemicals. Both provide worker protection and environmental protection. Also, you can modify either by adding a panel with two arm holes, and you can attach gloves to these so that you can reach into the cabinet.
If you have a Class I biosafety cabinet certification, you can enclose equipment in here or you can use it for procedures that generate aerosols. Unfortunately, the air that is drawn into this cabinet is not HEPA filtered, and the type of work you do inside the cabinet will determine whether you can exhaust the air outside the building or whether you must re-circulate it. This class of cabinet does not provide product protection, so it has very limited application.
There are several subcategories, but if your cabinets have Class II biosafety cabinet classification, they will be able to protect your product. The cabinet draws in air through a front grille and uses a HEPA filter to make this possible. The exhaust is similarly filtered so that you can re-circulate the air or exhaust it into the building. You can use these cabinets when working with microorganisms with biosafety levels 1, 2, or 3. They are useful to propagate cell culture and to formulate nonvolatile antineoplastic and chemotherapeutic drugs. If you have to work with volatile chemicals, you won’t be able to use the A1 subcategory. However, A2 and B1 cabinets can handle minute amounts and B2 cabinets can handle small amounts.