Classification Of Biosafety Cabinets

Biosafety protection mechanism (BSC) is based on the control and maintenance of stable airflow in, out and circulation in the cabinet, forming wind screens, insulating the outside and inside air. Airflow in and out of the cabinet is always filtered through the filter, which can eliminate the risk of contamination of the product and the surrounding environment.
Biological cabinets Class I
Protection of people working and the environment, not samples. Use with agents with low risk of infection.
Fixed front opening door
Air from outside is drawn directly into the cabinet, passing through the work surface

. The airflow rate to the cabinet must reach 0.36m / s to ensure protection.
Biological cabinets II
This type of cabinet is commonly used in microbiology laboratories and has the following characteristics:
Protect employees, products and surroundings with specialized ventilation
Mechanism of product protection thanks to the vertical airflow from the top of the work table after the membrane filter When it is close to the desktop (about 15-20 cm), the airflow will separate and enter the grooves in the front of the table and the back wall of the cabinet.
Air is released outside after filtering through HEPA membranes.



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Biological safety cabinets of Class II are divided into 4 types A1, A2, B1 and B2 and have their own characteristics to meet different usage requirements:
Biological safety cabinets Class II A1
The door opens to a height of 20-25 cm
There are exhaust fans to supply air from the outside to the cabinet, 70% of the return air and discharge 30% of the air outside when filtered through HEPA. Emissions can be discharged directly in the room or through the duct to the outside is openly connected to the exhaust vents of the cabinet.
The air entering the cabinet is maintained at an average speed of 0.4 m / s.
Due to the design characteristics, the contaminating air path in the cabinet may be at a higher pressure than the outside air pressure Therefore, the cabinet must be tight at this pressure area
A1 cabinets can work with low-risk agents and do not work with toxic chemicals or volatile radiation.
Biological safety cabinets Class II A2
Cabinets A2 have an inlet velocity of about 0.5 m / s. Contaminated air pipes or chambers are maintained at a pressure lower than the outside air pressure.



. Air from the cabinet can be discharged directly in the room.
A2 cabinets can also work with low-risk biological agents. In addition, the cabinet can also be used when working with toxic chemicals or volatile radioactive materials with very little dose. In these cases, the exhaust gas to the outside must be connected to an open pipe connected to the exhaust outlet of the cabinet
Biological safety cabinets Class II B1
The rate of air entering the cabinet is about 0.5 m / s.
Exhaust fan enters the cabinet at the bottom of the cabinet, HEPA filter is arranged under the table and in front of the exhaust fan. Air supply to the cabinet after filtration will be distributed from the top down.
About 70% of the emissions will be emitted outside the building through separate gas pipelines, 30% of the gas will be recovered and reused through HEPA filters.
Biological safety cabinets Class II B1 is used when working with microbiological agents with a low risk of infection.



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Biological safety cabinets Class II B2
Wind speed to the cabinet is about 0.5 m / s
Cabinets do not use return air
The air from outside is drawn into a cabinet by a fan, arranged by HEPA filter on the working table
The pipes and circulating chambers of the air are either exposed to negative pressure or are surrounded by pipes.
Biological safety cabinets of Class II B2 are used when working with microbiological agents with low risk of infection. In addition, cabinets are also used when working with biological agents treated with toxic chemicals or radioactive substances with extremely low concentrations.
It is very important to choose a biosafety cabinet that is suitable for the job requirements, and a full risk assessment related to practical techniques should be carried out. This is an important factor to ensure safety for employees working in laboratories and the surrounding environment.
KTV. HUYNH HUONG.

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