A biosafety cabinet ( BSC ) - also called biological safety cabinet or microbiological safety cabinet - is a closed laboratory workspace and ventilated to work safely with contaminated (or potentially contaminated) material pathogens requiring a defined level of biological safety. There are several different types of BSC, differentiated based on the required biocontainment level. BSC was first commercially available in 1950.
Video Biosafety cabinet
Destination
The main purpose of the BSC is to serve as a means to protect laboratory workers and the surrounding environment from pathogens. All HEPA exhaust air filtered out of the biosafety cabinet, removing harmful bacteria and viruses. This is in contrast to the laminar flow bench, which blows unfiltered waste air to users and is not safe to work with pathogenic agents. Both BSCs are safest to use as an acid cabinet. Similarly, the acid cabinet failed to provide the environmental protection that would be provided by HEPA filtering in the BSC. However, most BSC classes have a secondary purpose to maintain the sterility of the material inside (the "product").
Maps Biosafety cabinet
Class
The US Centers for Disease Control and Prevention (CDC) grouped the BSC into three classes. The BSC classes and types are divided into two ways: the level of personnel and the environmental protection provided and the level of product protection provided.
Class I
Class I cabinets provide personnel and environmental protection but no product protection. In fact, inward airflow may contribute to sample contamination. The inlet air stream is maintained at a minimum speed of 75 ° F,/min (0.38 m/s). This BSC is usually used to include special equipment (eg, centrifugal) or procedures ( for example. aeration culture) that potentially produce aerosols. BSC of this class either distribute (connected to building exhaust system) or released (recirculation filtered exhaust back to laboratory).
Class II
Class II Cabinets provide both types of protection (sample and environment) because the air of makeup is also filtered HEPA. There are five types: Type A1 (formerly A), Type A2 (formerly A/B3), Type B1, Type B2 and Type C1. Each type of requirement is defined by NSF International Standard 49, which in 2002 reclassified A/B3 cabinets (classified under the last type if connected to a sewer) as Type A2, and adds Type C1 in the 2016 standard. Approximately 90% of all biosafety cabinets which is installed is a Type A2 cabinet.
The principle of operation using a motor driven blower (fan) mounted in the cabinet to draw directional air flow around the user and into the air grille - protect the operator. The air is then pulled below the work surface and back to the top of the cabinet where it passes through the HEPA filter. HEPA columns are filtered, sterile air is also blown down, over products and processes to prevent contamination. The air is also discharged through the HEPA filter, and depending on the Class II BSC type, air is recirculated back to the laboratory or drawn by the exhaust fan, through the air duct where it is removed from the building.
Type A1 Cabinet, formerly known as Type A, has a minimum inlet velocity of 75 feet/min. Decreased air, considered contaminated, splits just above the work surface (BSC smoke) and mixes with the inrush. This air is drawn, through the air passages, to the back of the cabinet where it is then flung into positive pressure, contaminated plenary. Here, air will be recirculated, through a HEPA filter, back into the work zone, or exhausted from the cabinet (also via a HEPA filter). HEPA filter sizes and internal dampers are used to balance this air volume. This type is not safe to work with hazardous chemicals even when they run out with "thimble" or canopy to avoid interruption of internal airflow.
Type A2 Cabinet, previously designated A/B3, has a minimum inlet velocity of 100Ã, ft/min. A plenum of negative air pressure surrounds all plenaries of contaminated positive pressure. In other cases, the specifications are identical to the Type A1 cabinets.
Cabinet types B1 and B2 have a minimum inlet velocity of 100Ã, ft/min, and these cabinets must be hard-ducted to the exhaust system rather than fatigue through thimble connections. Their exhaust system should also be devoted (one BSC per duct run, per blower). Unlike the A1 and A2 type cabinets, Type B BSC uses a single pass airflow to control hazardous chemical vapors as well. Type cabinet B1 divides the air flow so that the air behind the smoke split is directed to the exhaust system, while the air between the operator and the smoke splits mixes with the inlet air and recirculates as the downstream. Since the exhaust air is pulled from the rear grille, the CDC recommends working with hazardous chemicals is done on the back of the cabinet. This is complicated, because the demigning the "back of the cabinet" is an invisible line extending the width of the cabinet (about 10-14 inches from the front grill) and drifts as an internal HEPA filter that loads with the particles.
Type B2 Cabinet (also known as Total Exhaust BSC) is expensive to operate because there is no air recirculation in it. Therefore, this type is mainly found in applications such as toxicology laboratories, where the ability to use harmful chemicals safely is important. In addition, there is a risk that contaminated air will flow into the laboratory if the disposal system for Type B1 or B2 cables fails to function. To mitigate this risk, this type of cabinet generally monitors the discharge stream, turns off the blower supply and sounds the alarm if the flow is not sufficient.
Type C1 BSC was born due to the need to control infectious materials, chemical hazards, reduced operating costs and added flexibility in modern laboratories. Type C1 moves air by mixing air in with air in the downflow air columns marked for recirculation. The air above the clearly illustrated part of the work surface is drawn by the second internal fan where it runs out through the HEPA filter. C1 differs from Type A because it can use this single airflow, and when installed in a distributed mode operation, it can protect from harmful chemicals, such as Type B. C1 also differs from Type B BSC in several ways; (2) awaiting risk assessment, BSC may run for extended duration to improve operator protection during long-range disposal failures, and (3) Type C1 BSC can running without connecting to the exhaust system at all.
Class II Cabinets are cabinets commonly used in clinical and research laboratories.
Class III
Class III Cabinets, generally only installed in the maximum detention laboratories, are specially designed to work with BSL-4 pathogens, providing maximum protection. The gas-resistant enclosures, and all materials in and out through a dunk tank or a two-door autoclave. Gloves attached to the front prevent direct contact with hazardous materials (Class III cabinets are sometimes called glove boxes). These custom-made cabinets are often installed in the line, and laboratory equipment mounted in them is usually specially made.
Ergonomics
Biosafety cabinets are used every day for hours. In addition to user protection and sample material, the human design factor (ergonomics) of the work becomes increasingly important. This includes noise level reduction (for a more comfortable working atmosphere), adjustable height or bench (for optimized seating position), panorama side windows (more light inside the cabinet), 10Ã, Â ° angled front elbow better seating position) as well as a strong light source (better look in the cabinet) to improve working conditions.
Ultraviolet light
CDC does not recommend the installation of UV lamps in BSC. The American Biological Safety Association supports this position, citing safety risks for personnel, shallow penetration, reduced effectiveness at high relative humidity, and frequent need to clean and replace light bulbs. UV lamps should not be used as the main source of surface decontamination in BSC. However, this statement has been formally debated in at least one article reviewed by colleagues showing that:
- There is no basis mentioned for the need to remove dust and dirt from lights
- Properly functioned biosafety cabinets have very clean air so that dust is less likely to build
- Laboratories are generally air-conditioned which removes concerns over moisture inhibition of UV effectiveness
- With proper use, the risk of UV exposure to users is very low
- Effective UV disinfection for germicides and virucide and inhibits DNA contamination from PCR
- UV disinfection has the advantage of leaving no residue such as a physical disinfectant
- The safety and relative risk of UV compared to other disinfecting techniques (which also contain risks) should be considered
Care and Service
Cabinets should be maintained on a regular schedule. During this certification check, airflow and filter capacity are verified. Filters have a limited lifespan - determined by the air quality in the laboratory space and the number of particles and aerosols generated within the BSC work zone. When this filter is loaded, an internal fan is required to do more work to push/draw the same air volume through it. The newer cabinets constantly measure airflow and compensate for fan performance to ensure constant air volume moves through filters and cabinets. If the flow falls below the desired performance, the audio and visual alarm will alert the operator. Changing filters should be restricted to people trained because the filters are potentially contaminated. This can be done either after the cabinet has been decontaminated using a gas procedure (using Formaldehyde, Chlorine Dioxide or Vaporized Hydrogen Peroxide) or bag-in/bag-out procedure.
When UV light is used, this lamp should be checked and changed as well. UV lamps reduce power over time, resulting in less disinfection of the work area.
Work Practices
As well as working on an open bench top, the work done in the BSC should be done with care and safety. To avoid contamination and exposure risk, the CDC advises researchers to follow best practices for reducing and controlling splatter and aerosol generators, such as keeping at least 12 inches (30 cm) of net material from aerosol generating activities and regulating workflows "From clean to polluted ". In particular, open flame, not necessarily in a clean environment of Class II or III BSC, causes interruption of internal airflow. Once work within the BSC has been completed, it is necessary to decontaminate BSC surfaces such as with laboratory equipment and other materials.
When the BSC is serviced or moved, including the replacement of a HEPA filter, it must be decontaminated gas. Gas decontamination involves filling BSC with toxic gas, the most common formaldehyde gas.
See also
- Acid Cupboard
- Laminar flow cabinet
References
Source of the article : Wikipedia
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