Biological safety cabinet classes

Laminar flow biological safety cabinet, class II. 

There are basically three Classes of biological safety cabinets. Classes I, II, and III. Class II units ate divided into two main sub-Classes, IIA and IIB. There are several versions of the latter of these two. All biological safety cabinets are intended to run continuously... 

Properly maintained biological safety cabinets (class II or III) are to be used for all manipulations of infectious materials. 

BIOLOGICAL SAFETY CABINET CLASS I A type of fume hood with an open face and fixed opening. Air is drawn in from the room and exhausted through the hood. This design is good for personnel protection but not protection of the research products. Suitable for LOW RISK or MODERATE RISK biological agents. 

BIOLOGICAL SAFETY CABINET CLASS II An open-front cabinet designed for personnel and product protection using HEPA-FILTERED recirculated air and HEPA-filtered exhaust for LOW RISK to MODERATE RISK AGENTS. 

Biological safety cabinets (BSCs) used in the United States are divided into three classes 1,11, and III. Class II cabinets are further divided into four types A, Bl, B2, and B3." In other countries, other categorization schemes are sometimes used, but usually follow the same general operating conditions. This division is quite unlike the rest of the local ventilation chapter, but since these descriptions are used whenever BSCs are used, it is practical to describe them here. 

Class U The Class U (Types A, Bl, B2, and biological safety cabinets provide personnel, environmental, and product protection. Airflow is drawn around the operator, through the hood opening and into the front grill of the cabinet, which provides personnel protection, in addition, the downward flow of HEPA-filtered air provides product protection by minimizing the chance of cross-contamination along the work surface of the cabinet. Because cabinet air has passed through the exhaust HEPA filter, it... 

The class I biological safety cabinet is intermediate between a fume hood and a closed glove box. This cabinet can be used with the front open or be fitted with gloves. Since the front access opening is normally only 8 inches high, the cabinet requires less ventilation than a fume hood. Class I cabinets are used with an airflow at the face of 100 linear feet per minute. 

In general, four types of cabinets are used for work with research quantities of chemical carcinogens. These are the conventional fume hood a Class I biological safety cabinet a Class II (Type B) biological safety cabinet and a Class III closed glove box system (8). 

The facility must be designed to control access. Signs should designate restricted areas. Clothing requirements for entry should be identified. There should be directional air control with adequate ventilation rates. Primary containment equipment such as chemical fume hoods, a Class I or Class II (Type B) biological safety cabinet, or a glove box system should be available for use with known or suspect chemical carcinogens or other toxic substances. 

Place the tumor material in a 10 cm Petri dish and cover with medium. This should be carried out in a class II biological safety cabinet. 

Laboratories should process specimens in a class 11 biological safety cabinet using level 3 practices. When possible, staff should pretreat serum with a combination of heat-inactivation at 56°C and polyethylene glycol p-tert-octylphenyl ether (Triton X-1(X)). Although treatment with lOuL of 10% Triton X-100 per 1 mL of serum for an hour reduces the virus titer in the serum, laboratory staff should not assume that the resulting viral titer is zero. For laboratory tests in which detergent use could alter the results, heat inactivation alone may help reduce the viral load and consequent infectivity of the sample. 

A unit sometimes confused with a Class I biological safety cabinet is a horizontal laminar flow cabinet or work table. This type of unit serves precisely the opposite function of a class I cabinet. Clean air which has been HEPA filtered is blown across the work surface toward the worker so that the research or product materials are protected against contamination, but the worker is not protected at all. Such a unit is unsuited for microbiological work, except for applications which would cause no harm to the users, such as a work involving noninfectious or non-aUergenic materials. 

Class IIB biological safety cabinets differ in several ways from Class IIA cabinets. Two major differences are the amounts of air recirculated (a much smaller proportion for a type B unit than for a type A) and that the air in the plemms surrounding the work area is filtered or clean air rather than... 

Certification of Class II (Laminar Flow) Biological Safety Cabinets, (slide/cassette) NAC no. 003134 and no. 009771, National Audio Visual Center (GSA), Washington, D.C., 1976. 

Within the work areas ofthe facility, all activities are confined to Class III biosafety cabinets, or to class II biological safety cabinets used with one-piece positive pressure personnel suits ventilated by a life support system. The facility is to be designed to prevent discharge of microorganisms into the environment. 

FIGURE 7.3.4.3 Canopy Unit Exhaust for Class II Type AI BSC. The canopy unit (sometimes called the thimble) is designed to fit over the exhaust of the BSC but not tightly. There is a gap of about 1 inch between the canopy and the BSC exhaust so that air is also exhausted from the room. Canopy units are often used in small lab rooms where some exhaust ventilation is needed to remove chemical contaminants that might be in the air. (From Figure 4 in CDC/NIH, Primary Containment for Biohazards Selection, Installation, and Use of Biological Safety Cabinets, 3rd edition, CDC/NIH, Washington, DC, 2007 available at http //www.cdc.gov/od/ohs/biosfty/primary containment for biohazards.pdf.)... 

All procedures conducted in Class ni Biological Safety Cabinets or Class I or II Biological Safety Cabinets in combirration with full-body, air-supplied, positive pressure suit... 

Class I, n or in Biological Safety Cabinets available for manipulative procedures (inoculation, necropsy) that may oe-ate infectious aerosols... 

Maximum containment equipment (i.e.. Class II Biological Safety Cabinet or partial containment equipment in combination with full body, air-supplied positive-pressure suit) used for all procedures and activities... 

Biological safety cabinets are partial or full enclosures where the air flow designs keep agents within the cabinets. There are three classes of cabinets ... 

Class I Biological Safety Cabinets. A Class I biological safety cabinet has an open front. Air moves inward across the face at 75 ft/min or higher and exhaust air moves through high efficiency particulate air (HEPA) filters. 

Class II Biological Safety Cabinets. A Class II biological safety cabinet also has an open front with a 75 ft/ min face velocity. It has vertical laminar flow air movement. The air moves through HEPA filters and gets recirculated within the cabinet. Some air also... 

Characterize Class I, Class II and Class III biological safety cabinets. 

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