Scenario 1: Biosafety Cabinets I, II and III
BSCs provide both a clean work environment and protection for people who work with biological hazards. BSCs use vertical laminar airflow to create a blockage against airborne particles. They use High Efficiency Particulate Air (HEPA) filters to decontaminate air entering the work area and out to the surrounding. The air in most BSCs is recirculated by the HEPA filter. The HEPA filter removes airborne particles from the air, excluding chemical fumes.
Use a BSC for experiments with human pathogens that may release aerosols (e.g. vortexing open tubes, pipetting, opening caps after centrifuging, sonicating, aspirating with a syringe, etc.), as well as experiments with airborne transmitted pathogens (such as Brucella abortus, Mycobacterium tuberculosis, etc.).
Class I: An open-front negative pressure cabinet. The exhaust air is filtered by a high-efficiency particulate air (HEPA) filter. The Class I biosafety cabinet will provide personnel and environmental protection, but not product protection.
An example of a Biosafety Cabinet Class I would be as follows...
Class II: An open-front, ventilated cabinet, it provides HEPA-filtered, recirculated mass airflow within the work space. Thus, the Class II biosafety cabinet will provide personnel, environment and product protection. While HEPA filters are useful for trapping particulates and infectious agents, these filters do not capture volatile chemicals or gases.
An example of a Biosafety Class II cabinet would be as follows...
Class III: A totally enclosed ventilated cabinet of gas-tight construction. Experiments within the Class III cabinet are carried out through attached rubber gloves. During use, the cabinet is maintained through negative air pressure of at least 0.5 inches water gauge. Supply air is drawn into the cabinet through HEPA filters. The cabinet exhaust air is filtered by two HEPA filters, installed in series, before discharge outside of the facility. The exhaust fan for the Class III cabinet is generally apart from the exhaust fans of the facility's ventilation system.
An example of a Biosafety Cabinet Class III would be as follows...
Image obtained from http://www.etelstar.com
An example of a Biosafety Cabinet Class III would be as follows...
Contaminated air is then drawn into a blower that travels about 1/3 of it through an exhaust HEPA filter and then out to the surroundings. The other 2/3 of the contaminated air is transported back down through a workspace HEPA filter located directly over the work surface. This fills the work surface with clean HEPA-filtered air, and provides a blockage to prevent unfiltered room air from entering the area of the work surface. Biological safety cabinets utilize HEPA filters to provide maximum protection for products, people, and the laboratory environment. In order to ensure optimal safety and performance these HEPA filtration devices, regular tests have to be conducted and have the devices re-certified by qualified professionals.
References:
Esco. (2012). Labculture® Class II, Type A2 Biological Safety Cabinet [Digital Image]. Retrieved from http://www.escoglobal.com/product.php?id=LA2-A
Iowa State University. (2005). Biosafety Cabinets. Retrieved from http://www.ehs.iastate.edu/cms/default.asp?action=article&ID=40
Nuaire. (n.d.). LabGard 813 Class I Biosafety Cabinet [Digital Image]. Retrieved from http://www.nuaire.com/labgard/813/class1-vented-balance-enclosure.htm
Telstar. (2009). High Containment Biosafety Cabinet [Digital Image]. Retrieved from http://www.etelstar.com/en/communications/news/high+containment+biological+safety+cabinet.htm
World Health Organization. (2004). Laboratory Biosafety Manual (3rd ed.). Retrieved from WHO, Geneva: http://www.who.int/csr/resources/publications/biosafety/Biosafety7.pdf
Labels: Biosafety cabinets I, II, III
posted by Michelle, Bernadette, Shanna, Karen, Su Wei, Shi Ting @ 16:36
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