How to buy a biological safety cabinet? Reference recommendations for selection of biological safety cabinets

Type A2 and B2 biological safety cabinets are both second-class biological safety cabinets, and their differences are as follows:
1. The main difference between the A2 safety cabinet and the B2 safety cabinet is that the exhaust airflow of the A2 safety cabinet is efficiently filtered and then returned to the room; the exhaust airflow of the B2 safety cabinet is efficiently filtered and then discharged to the outside.
2. Since the two types of biological safety cabinets are filtered and then discharged, the two types of safety cabinets are not very different in terms of biological safety.
3. If the experiment subject may escape radioactive gas or explosive gas, please choose B2 type safety cabinet, otherwise, choose A2 type safety cabinet.
4. If you choose the B2 type safety cabinet, please ensure that the laboratory has sufficient ventilation, otherwise it will cause the safety cabinet to suck the wind speed too low, causing an alarm and seriously reducing its biological safety.
5. If the selected B2 biological safety cabinet is used in midsummer or severe winter, due to its large ventilation volume, a large amount of outdoor air flows into the room, which may cause the laboratory environment to be too hot or cold. Please fully consider this before selecting a model One situation.
Supplement:
Biosafety cabinets are biological safety protection and isolation equipment used in microbiology, biomedicine, biosafety laboratories and other laboratories. It adopts advanced air purification technology and negative pressure box design to achieve protection of the environment, personnel and samples, which can prevent the spread of harmful suspended particles and aerosols; provide cross-infection and environmental protection between operators, samples and samples Safety protection is the most basic safety protection equipment in the first-level protective barrier of laboratory biological safety. A bracket-type structure is adopted, and the bracket and the box body can be separated, which is convenient for transportation and positioning.
The specific introduction of the two biological safety cabinets:
Class II A2 biological safety cabinet
(1) The minimum suction air velocity is 0.5m / s;
(2) The vertical airflow is a part of the mixed vertical airflow and suction airflow (not more than 70%);
(3) The exhaust must be filtered by HEPA before it can be discharged outdoors;
(4) All air ducts and static pressure boxes contaminated with biological materials should maintain negative pressure or be surrounded by negative pressure air ducts and static pressure boxes.
Class II B2 biological safety cabinet (1) The minimum suction air velocity is 0.5m / s;
(2) The vertical airflow filtered by HEPA is sent from the laboratory or outdoor air (usually called fresh air, that is, the gas discharged from the safety cabinet does not participate in the circulation process);
(3) All the inhaled airflow and vertical airflow are filtered by HEPA and discharged into the atmosphere, and do not enter the safety cabinet or return to the laboratory;
(4) All contaminated air ducts and static pressure boxes maintain negative pressure, and the airflow in the work area is directly evacuated.