Class I cabinets

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. 

Sonicate sample (see Note 3) within a MSC class I cabinet to minimize exposure to aerosols. It may be necessary to mince with fine scissors or add glass beads to the sample to aid sonication (see Note 12). 

A Class I cabinet, used properly, can provide excellent protection for the research worker, but it does not provide any protection for the active work area within the cabinet, since the air flowing into the cabinet is dirty air, i.e., ambient air from the room that has not been specifically cleaned. For chemical work, this was not discussed since it is rarely a concern of... 

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. 

Although HEPA filters with a penetration of less than 0.003% are considered to remove airborne bacteria, the Code of Practice for the Prevention of Infection in Clinical Laboratories and Post-mortem Rooms considered that effluent air from Class I cabinets should be exhausted to... 

The Class I cabinet is the simplest of the safety cabinets (Figure 9.4). This class of cab-... 

Figure 9.4 Class I safety cabinet. Top, diagram showing air flow directions for left, open front center and right, glove port front. Bottom, photograph of a Class I cabinet. (Photograph courtesy of the Baker Co.)...

The face of the basic Class I unit can be adapted for different operations. A panel containing arm ports can be fitted to some models, and certain of these can be provided with arm-length neoprene gloves (see Figure 9.4). This latter adaptation converts the cabinet into a glove box, but it does not make the Class I cabinet into a Class III unit. These adaptations will, however, reduce the chance of product contamination while increasing operator protection. 

The Class I cabinet should be installed in a location away from traffic flow to avoid creation of air turbulence inside the cabinet that would interfere with proper operation. This is a problem because an open-front Class I cabinet has a face velocity requirement of only 75 linear feet per minute. However, a person walking moves at about 200 to 260 feet per minute thus people moving by the cabinet can seriously disturb the cabinet s operation. 

Class I BSCs are, from the functional view, similar to a fume cupboard (Section 10.2.3). Class II cabinets are used for product and worker protection. Class III cabinets are used for work with very dangerous microbiological or radioactive agents and provide maximum protection to the environment and the worker. The class and type of BSC used is dependent on the demands for worker and product protection. 

Some Class I BSCs are equipped with an integral exhaust blower the cab inet blower must be tiiterloclced with the building exhaust fan. In the event that the building exhaust fan fails, the cabinet exhaust blower must also turn off so that the exhaust ducts are not pressurized. If the ducts are pressurized and the HEPA filter develops a leak, contaminated air could be discharged into other parts of the building or the environment. 

Class I-III Cabinets Containment cabinets used for various requirements. In a high-risk area, a Class III cabinet would be used. Class I and II cabinets are used in low-risk areas. 

The equipment used in this application included two Waters M-45 pumps, a Waters 481 UV detector with microbore cell, an air-actuated Rheodyne 7413 injection valve with a 1-pl injection loop, an air-actuated Valeo four-port sampling valve (A2CI4UW2) with no groove in the injection entry ports, an air-actuated Valeo three-port switching valve (AC3W), and a Digital Equipment LSI-11/23 microcomputer. The LC system was located in a purged cabinet suitable for use in Class I, division 2 areas. The cabinet was in a heated room about 40 feet from the reactor column. The two Valeo valves were mounted next to the reactor column, while the microcomputer was located in the control room. 

BSL 2 Biosafety Level 2 is suitable for work involving microorganisms of moderate potential hazard to personnel and the environment. Safety equipment Class I or II biosafety cabinets or other physical containment devices laboratory coats, gloves, face protection as needed. Microorganisms include hepatitis B virus, HIV, salmonellae, and mycoplasma. 

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. 

Class I BSC. The Class I BSC is an open containment unit suitable for work involving agents of low to moderate risk to the user and environment, where there is a need for containment but none for product protection or isolation. The Class I BSC provides protection to personnel using the cabinet by means of constant, controlled airflow into the work area and away from the operator, preventing the escape of aerosols through the front opening. It is of limited use in manufacturing and has no reported use in the current practice of pharmacy. 

Regular maintenance of biological (microbiological) safety cabinets is essential. National standards, for example, British Standard BS 5726 1992, have been set for their construction, installation and operation. The inward face air velocities of Class I and II cabinets must provide an operator protection factor of at least 1 x 105 (for every 100,000 particles released at the working aperture, no more than one should escape into the laboratory). Also, HEPA fdters must have a mini-... 

NFPA 45, 2.2.1.4 4.3.15 With the exception of Section 4.3.12 and 4.3.13, all Class I, II, and IIIA flammable and combustible liquids not in a flammable liquids storage room shall be stored in flammable liquid storage cabinets when not in use. 

NFPA 30, 4.5.S.3 4.4.5 In an office occupancy, not more than ten gallons (37.8 liters) of Class I and Class II liquids (see definition) combined shall be kept in a single fire area (see definition) outside of a storage cabinet or an inside liquid storage area, unless the liquids are in safety cans (see definition). 

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... 

A properly functioning HEPA filter is an essential component in both Class I and Class II units and may be important in some Class III biosafety cabinets. 

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