A brief introduction and classification of biosafety cabinets

Biosafety cabinets are designed to protect the operator, laboratory environment and experimental materials from exposure to infectious aerosols and splashes that may occur during the operation of primary cultures, bacterial strains and diagnostic specimens.





The ultra-clean work table can only protect the reagents operated within the work table from contamination and does not protect the staff, while the biosafety cabinet is a negative pressure system, which can effectively protect the staff.





According to the difference of biosafety protection level, biosafety cabinet can be divided into three types: first class, second class and third class.



Class I biosafety cabinets protect workers and the environment without protecting samples. The principle of air flow is basically the same as that of the laboratory fume hood, except that HEPA filter is installed in the exhaust port to filter the exhaust flow and prevent the spread of microbial aerosol pollution. The first-level biosafety cabinet itself has no fan, and relies on the fan connected to the air duct externally to drive the airflow. Due to the failure to protect the products inside the cabinet, it has been rarely used at present.





The second class biosafety cabinet is widely used at present. According to the provisions of yy0569-2005 biosafety cabinet of the pharmaceutical industry standard of the People's Republic of China, the second-level biosafety cabinet can be divided into 4 levels according to the inlet air speed, exhaust mode and circulation mode: type A1, type A2, type B1 and type B2. All secondary biosafety cabinets provide protection for staff, environment and products.





Class B biosafety cabinets are all safety cabinets connected to the exhaust system. The fan connected with the exhaust duct of the safety cabinet is connected with the emergency power supply. The purpose is to maintain the negative pressure of the safety cabinet in case of power failure, so as to avoid dangerous gas leakage out of the laboratory. The air velocity in the front window shall be small or the measured mean shall be at least 0.5m/s(100fpm).





Biosafety level 3 biological safety cabinet is for designed for grade 4 laboratory, cabinet put oneself in another's position completely airtight, staff by connecting the cabinet put oneself in another's position of gloves, commonly known as the glove box (Golve box), the experiment through a two-door pass box in and out of safety cabinet to ensure that from the pollution, is suitable for the high risk of biological experiments, such as SARS, the ebola virus related experiments.