Biological Safety Biosafety Cabinet BSC

According to the provisions of international standards, biological safety cabinet is divided into 1, 2 and 3 class, of which class 2 biosafety cabinets are the most commonly used in laboratories at present.

1. Class 1 biological safety cabinet

Class I biosafety cabinet protect workers and the environment. Since the unsterilized room air is blown directly to the workbench surface through the front operating window of the biosafety cabinet, the class 1 safety cabinet cannot provide practical protection for the operating object.

2. Class II biosafety cabinet

The unfiltered air will be introduced into the air inlet grille by the built-in fan before reaching the working area, and the experimental specimen will not be contaminated by the outside air. The air flow is filtered by HEPA filter and then sunk vertically. The sinking air flow is dislodged 618cm away from the workbench, taking away the aerosols formed on the workbench, and discharged through the front and rear air grille respectively, thus providing protection for the staff and test subjects. The class II biological safety cabinet can be divided into four types according to the inlet air speed, exhaust mode and circulation mode: A1 type, A2 type, B1 type, B2 type.

2.1 Class II type A2 biosafety cabinet

The minimum flow rate of air flow at the operating port of the front window of the class 2 type A2 biosafety cabinet is 0.5m/s. 70% of the gas is recirculated to the working area through the HEPA filter, and 30% is filtered out through the exhaust port. The design of the class II A2 biosafety cabinet with negative pressure around the contaminated area prevents the leakage of substances in the cabinet.

2.2 Biosafety cabinet class 2 type B

Biosafety cabinet class 2 type B is a safety cabinet connected to the exhaust system. The fan connected to the exhaust pipe of the safety cabinet is connected to the emergency power supply, and the negative pressure of the safety cabinet can be maintained even when the safety cabinet is powered off. The minimum airflow rate of the front window operating port is 0.5m/s. (1) 70% of the B1 gas is discharged through the exhaust port HEPA filter, and 30% of the gas is recirculated to the working area through the supply port HEPA filter. Negative pressure should be maintained in all bio-contaminated areas. (2) Type B2 is a 100% full-row safety cabinet with no internal circulating air flow. The air flow in the cabinet is filtered and discharged into the atmosphere, and no longer enters the safety cabinet circulation, which can provide both biological and chemical safety control.

3. Biosafety cabinet class 3

Biological safety cabinet class 3 is the highest level of safety protection safety cabinet, suitable for class 3 and class 4 biosafety laboratories. The cabinet is completely airtight, 100% full discharge type, all gases do not participate in the circulation, the staff through the glove connected to the cabinet to operate, the test product through the double-door transfer box in and out of the safety cabinet to ensure that it is not contaminated, suitable for high-risk biological tests.

At present, the biosafety cabinets commonly used in the handling of biological specimens such as the novel coronavirus outbreak are Class II A2 and B2 biosafety cabinets, which play an important role in biosafety protection in the fight against the epidemic and effectively protect operators and the environment.