Views:16 Author:Leon Publish Time: 2020-08-26 Origin:百度百科
Biosafety cabinets, also known as biological safety cabinets, are enclosed, ventilated laboratory workspace areas designed to protect the user and surrounding environment from pathogens. All exhaust air is HEPA filtered to remove hazardous agents such as viruses and bacteria. Biosafety cabinets are used in many laboratories including clinical and research labs. Biosafety cabinets are divided into three classes: I, II and III. Class I provides protection for the user and surrounding environment, but no protection for the sample being manipulated. Class II provides protection for the user, environment and sample, and is divided into four types: A1, A2, B1 and B2. The main differences are their minimum inflow velocities and exhaust systems. Class III, also known as glove boxes, provides maximum protection; the enclosure is gas-tight, and all materials enter and leave through a dunk tank or double-door autoclave. Choice of cabinet therefor depends on level of protection needed for the laboratory worker and the sample of interest.
The working principle of the biological safety cabinet is mainly to suck the air inside the cabinet to maintain a negative pressure in the cabinet and protect the staff through the vertical airflow; the outside air is filtered by a high-efficiency particulate air filter (HEPA) After filtering, enter the safety cabinet to avoid contamination of the processed samples; the air in the cabinet also needs to be filtered by a HEPA filter before being discharged into the atmosphere to protect the environment.
According to the NSF49 standard, the medium of biosafety level 1 (P1) refers to microorganisms such as ordinary harmless bacteria and viruses; the medium of biosafety level 2 (P2) refers to microorganisms such as general pathogenic bacteria and viruses; biosafety The medium of level 3 (P3) refers to microorganisms such as potent/fatal bacteria and viruses, but can be cured after infection; the medium of biosafety level 4 (P4) refers to microorganisms such as potent/fatal bacteria, viruses, etc., and it is not easy to cure after infection . This standard divides biological safety cabinets into grades I, II, and III, which can be applied to the operation of media of different biological safety grades.
When the laboratory level is level 1, there is generally no need to use a biological safety cabinet or a level I biological safety cabinet. When the laboratory level is level two, when microbial aerosols or spills may occur, a level I biological safety cabinet can be used; when handling infectious materials, a level II biological safety cabinet with partial or full ventilation should be used ; If it involves handling chemical carcinogens, radioactive substances and volatile solvents, only Class II B full exhaust (B2 type) biological safety cabinets can be used. When the laboratory level is level three, a level II or level III biological safety cabinet should be used; all operations involving infectious materials should use a fully exhausted type II B level (B2 type) or level III biological safety cabinet. When the laboratory level is level four, a level III full exhaust biological safety cabinet should be used. When personnel wear positive pressure protective clothing, a Class II B biological safety cabinet can be used.