Clean bench ⁄ Biosafety Cabinet ⁄ Isolator
Clean Bench (ABH)
Clean bench (ABH) is a laminar flow work cabinet or alike enclosure that provides filtered air over the work surface to protect against contamination. Clean bench allows providing a clean area without dust. Contamination air is expelled outside the area and made safe through filtration to provide environmental and personal protection.
Clean benches provide a stream of air that moves from one end of the cabinet, across the working space, to the opposite side of the cabinet, then into the room in which it is located. Clean benches have two possible airflow patterns: rear to front in horizontal models, or top to bottom in vertical models. In both models, the air is taken in from above the cabinet and passed through a HEPA filter.
It is mainly used in factories, laboratories, food processing, aerospace, bioscience, etc. It can also be designed and manufactured according to customer requests.
· Horizontal flow air is then passed through the main chamber of the clean bench in a horizontal laminar (unidirectional) air stream and is exhausted through the front opening of the cabinet.
· Vertical flow air is passed through the main chamber of the clean bench in a vertical laminar (unidirectional) air stream before being exhausted through the front opening of the clean bench.
Biosafety Cabinet (BSC)
Biosafety cabinet (BSC), also known as biological safety cabinet, provides protection for the surrounding environment, and it is used to protect personnel against biohazardous or infectious agents and to help maintain quality control of the material being worked with as it filters both the inflow and exhaust air. BSC exhaust air is passed through a certified high-efficiency particulate air (HEPA) filter, which is effective at trapping particulates and infectious agents. Several different types of BSC exist, differentiated by the degree of biocontainment they provide. The requirements are defined by Biological Safety Levels (BSL), which distinguished healthy and safety risks between BSL-1, BSL-2, BSL-3, and BSL-4 environments.
· BSL-1: It is required in the presence of microbes that do not always cause disease, such as E. coli.
· BSL-2: It is required in the presence of moderately hazardous microbes, such as Staphylococcus aureus.
· BSL-3: The supply and exhaust gas of this type of safety cabinet must be filtered by HEPA FILTER. The lab is restricted behind two sets of doors.
· BSL-4: It is required in the presence of high risk of airborne transmission; infections are regularly fatal, as from Ebola.
It is used to operate equipment for biological hazards, radioactive substances, harmful chemicals, COVID 19, and other substances.
Biological safety cabinet classes are classifications describing exactly how the cabinets work and what it protects. The National Science Foundation designated three classes for BSCs:
· Class I: It is defined as a ventilated cabinet for personnel and surrounding protections. These compounds shelter personnel, but cannot shelter products within the hood. These cabinets have a similar airflow pattern to a fume hood but they also have a HEPA filter at the exhaust outlet. They may or may not be ducted outside. Class I cabinets are safe for use with agents requiring Biosafety Level 1, 2, or 3 containment.
· Class II: it shelters both operator and product. These units supply a HEPA filtered laminar flow of air to shelter the product from contamination, like a laminar flow hood. There are four common types of Class II BSCs are prominent by air velocity as well as the percentage of air that is recycled versus exhausted. Like Class I cabinets, Class II cabinets are safe for work using agents requiring Biosafety Level 1, 2, or 3 containment.
‧ Type A1(formerly Type A):70% of air is recirculated and 30% is ducted. Must maintain a minimum inflow velocity of 75ft/min.
‧ Type A2(formerly Type A/B3): 70% of air is recirculated and 30% is ducted. Must maintain a minimum inflow velocity of 100ft/min.
‧ Types B1 and B2 have reliable hard-ducted exhaust lines,70% air exhaust in Type B1 and 100% in Type B2.
· Class III: It provides the utmost level of protection when working with very dangerous pathogens. Class III biosafety cabinets are also called glove boxes. Exhaust air is HEPA filtered and directed into a ducting system. It is safe for work requiring Biosafety Level 1,2,3 or 4 containment.
Isolator
The isolator is designed to avoid the risk and to protect the product from both the process and externally generated factors. The sterility testing is conducted by direct inoculation or membrane filtration methods and can be performed in an isolator or cleanroom environment.
Sterility testing procedures are applied to products in many industries, but it is mainly used in the pharmaceuticals and medical sectors where the sterility testing of the products remains a vital and routine task for microbiologists.
Sterility testing should be carried out under strict aseptic conditions. Sterility isolator is designed in such a way to allow samples, equipment, and consumables to be loaded onto appropriate shelving and base trays, which will allow minimal blocked surfaces.
