Introduction of Biosafety Cabinet

A variety of microbial operations in the laboratory may produce aerosols, such as pipette operations, centrifugal precipitation, dipping liquids with inoculation loops, opening ampoules, mechanical shocks, strain dilution or inoculation operations, etc. In addition, some accidents during experimental operations, such as liquid pouring or splashing will produce aerosols. Therefore, in the laboratory, in order to avoid the infection of pathogenic microbial aerosols to operators and the environment, and to achieve isolation between them, a microbial safety cabinet must be used.

The diameter of the aerosol particles scattered in the air is generally 1~5μm, which cannot be observed by the naked eye, so laboratory operators are usually unaware that aerosols are generated during the operation and may be inhaled, or caused on the work surface during the experiment. Cross-contamination with other experimental materials.

Correct use of biological safety cabinets can effectively reduce laboratory-acquired infections and cross-contamination between experimental materials caused by exposure to aerosols, and biological safety cabinets can also play a role in protecting the environment. Therefore, biological safety cabinets are widely used in microbiology laboratories.

The Class I safety cabinet has a front window operation port, and the operator can operate in the safety cabinet through the front window operation port. The negative pressure air inhaled from the front window operation port can protect the safety of the operator, and the exhaust air is filtered by the high-efficiency filter and discharged into the safety cabinet to protect the environment.

However, because the unsterilized room air is directly blown onto the work surface through the opening on the front of the biological safety cabinet, the Class I biological safety cabinet cannot provide reliable protection for the operating objects, that is, operations that require sterile and clean conditions cannot be performed. Due to the inability to protect the products in the cabinet, it has been rarely used at present.

Principle of Class II biological safety cabinet: Class II safety cabinet has a front window operation port, and the operator can operate in the safety cabinet through the front window operation port. After the air supply of Class II safety cabinet is filtered by the air supply high-efficiency filter, a vertical one-way airflow with a certain speed is formed from the top down to avoid cross-contamination between samples. Vertical airflow at a certain wind speed also prevents unfiltered air from entering the room directly into the work surface, thus protecting the sample. The negative pressure air inhaled inward from the front window operation port can protect the safety of the operator. Technical points:

Class II biological safety cabinets can not only provide personnel protection but also protect the items on the work surface and the environment from contamination. Class II biological safety cabinets are currently the most widely used cabinet types.

There are two different types of Class II biological safety cabinets in the NFS 49 standard in the United States. According to the proportion of exhaust air, they are A-type and B-type respectively. A-type is divided into A1-type and A2-type according to whether there is an exhaust-air pipeline, B-type is divided into B1-type and B2-type, and the EN12469 standard in Europe is not classified.