A biosafety cabinet is a ventilated enclosure, designed for safely work from biohazardous materials. The primary purpose of a BSC is to protect the laboratory worker and the environment from pathogens during routine procedures. The secondary is to maintain the sterility of materials on the work surface.
Biosafety cabinets Classifications and Types
There are three biological safety cabinet classes (Class I, II and III) based upon the protection they provide to the user, environment and product. The higher the class, the greater the protection from various hazards that can emerge while working with pathogenic agents
Class I biosafety cabinet
Class I is a biological safety cabinets with a basic design, used to provide only personnel and environmental protection. This class provides only user and environment protection for work with agents requiring Biosafety Level 1 – 3 containment. It has no specific feature to prevent the samples from coming into contact with airborne contaminants present in room air.
How Class I biosafety cabinet works?
Class I biosafety cabinet has a very similar airflow pattern to the fume hood. During a procedure, a stream of room air moving into the cabinet through the front opening. The operator is protected by continuously delivering airflow (min velocity 75)away from him. The continually entered air passes across the work surface where the simple may contact with airborne contaminants.
Then the air is drawn through a filtration system (HEPA) and a built-in exhaust fan located at the top of the work zone. The filter removes all airborne particles and contaminants, providing environmental protection.
How does Class II biosafety cabinet work?
Class II biosafety cabinet provides user, environment and product protection. It used in laboratory applications, requiring Biosafety Level 1 – 3 containment.
There are two types of Class II (Type A and Type B) based on their construction and configuration. The main differences are the percentage of air exhausted to that of air recirculated from the common air plenum. They may have different means of exhaust: some may exhaust air directly back into the laboratory; others may exhaust air via ductwork.
Copyright ©2020 Laboratory-Report.com. All Rights Reserved
How Biosafety Cabinet Type A1 and A2 work?
The airflow is drawn into the work surface via the front opening and continues under the worktop. The inward airflow provides personnel protection.
Next, it goes up the back plenum, where 70 % or more is being recirculated through the primary HEPA filter to provide downflow over the work area. Downward HEPA filtered laminar provides product protection.
30 % of the airflow exits out through the HEPA filter to exhaust with a thimble type duct connection. This way, type A is providing environmental protection.
The downward airflow is passing through a HEPA-filter to protect the product from getting contaminated. The air is then drawn downward and brought up through a duct from the back. The air is blowing to positive pressure. Following this, the air might be recirculated into the plenum after HEPA filtration or exhausted out of the cabinet. The exhausted air is HEPA filtered. A1 can be used to work with biological agents but is not suitable to work with hazardous chemicals.
A2 type cabinets are similar to A1 type cabinets. The significant difference is in the speed of inflow air and contaminated plenum. In A1 is bordering ambient air, where on the A2, it is surrounded by negative pressure.
A2 cabinets with the canopy attached are using to treat biological agents that have fragrant quantities of hazardous chemicals.
How Biosafety Cabinets Type B1 and B2 works?
Biosafety cabinets type B require specific installation and operating conditions to function correctly. It needs to maintain a minimum average inflow velocity of 100 fpm and be hard-connected to an external ventilation system.
In type B1, the airflow is pulled into the work surface through the front opening and continues under the worktop. It goes up the back plenum, where 70 % is exhausted through the HEPA filter to an external ventilation system. The rest (30%) of air is recirculating within the cabinet.
In type B2, room air is pulled through a blower installed at the top of the cabinet and pushed through a HEPA supply filter into the work area. At the same time, room air enters through the front opening is pulled through the perforated front grill. 100 % of the HEPA filtered air is exhausted from the cabinet.
Type B2 cabinets are suitable for work with agents treated with volatile toxic chemicals and radionuclides.
A2 vs. B2 Type Biosafety Cabinet link
How Class III biosafety cabinet works?
Class III, also known as glove boxes, provides maximum product, personnel and environment protection. They are used to work with agents that require Level 1-4 containment for biosafety. These are also known as glove boxes. Mostly, Class III biosafety cabinets are using in industries and laboratories that require maximum containment.
Class III (biosafety cabinets) are considered the most secure and full proof of biosafety cabinets. They are ventilated cabinets, which are gas-tight and leak-proof. Rubber gloves are attached to the cabinet preventing direct contact of the user with the hazardous materials.
Room air is passing through a HEPA filter that provides product protection and prevents cross-contamination of samples. During operation, negative pressure relative to the ambient environment maintained within the enclosure. This process offers additional safety in a case in physical containment. The air exhaust usually back to the laboratory through HEPA filter via a dedicated ductwork system to the external environment. Materials are moved into the glove box using a pass-through unit installed at the work area that sterilizes the materials before leaving the compartment.