Let's get started talking about biosafety cabinets, what they are, what classes they fall into, and what types they come in.
What are Biosafety Cabinets?
Biosafety Cabinets (BSCs) are covered work areas with a ventilated hood that are used to keep pathogenic bacteria contained throughout microbiological activities.
What are biosafety cabinets used for?
you might wonder? Biological Safety Cabinets are used to safeguard personnel and the atmosphere from harmful microbes, as aerosols may be created during the handling of such microorganisms. They are also used for specific based on the risk microbes and procedures that may result in aerosol creation.
HEPA filters are installed in biosafety cabinets to purify the air leaving the cabinet. They may be mistaken also with a laminar hood because both of those items provide enclosed workstations. However, a laminar hood protects just the sample, not the employees or the surroundings, whilst biosafety cabinets safeguard all three.
BSCs are critical components of biosafety because they reduce the generation of aerosols, environmental protection, the pathogen, and laboratory personnel.
Now that we know what a biosafety cabinet is, let's look at the many types of biosafety cabinets.
Biosafety Cabinet Classes
The United States Centers for Disease Control and Prevention (CDC) divides biosafety cabinets into three categories, each with its own set of operational features and purposes.
- ●Biosafety levels I and II require any use of Class I and II Biosafety cabinets, which, when combined with appropriate microbiological procedures, help in providing appropriate containment vessels for the secure management of medium and high-risk pathogens.
- ●Class III BSCs are best for working with hazardous substances that require a Biosafety Level 3 or 4 certification.
1. Biological safety cabinets Class I
The most fundamental biosafety cabinet, Class I, provides environmental and laboratory worker protection. But, because the unsanitary room air is drawn across the work surface, it does not offer product protection. These Class I biosafety cabinets are often used to contain sophisticated equipment, such as centrifuges, or operations, such as aerating cultures, that could emit aerosols.
This variety of biosafety cabinets can be ducted (attached to the room's exhaust system) or unducted (not connected to the room's exhaust system) (recirculating filtered exhaust back into the laboratory). The room air is pulled in via the entrance in the Class I BSC, which also enables the operator's arm to enter during operation. The air on the inside of the cabinet then sucks in any created aerosol particles and transports them away from the operator to the HEPA filter.
2. Biological safety cabinets Class II
Because the composition air is also HEPA-filtered, BSC-Class II cabinets offer both forms of protection (for the samples and the environment). A fan installed on the top of the cabinet spreads a curtain of sterile air over the workstations where biological items are processed, which is how Class II cabinets work.
The air then passes through the HEPA filters after traveling beneath the workstation and back up to the top of the cabinet. Air is sucked through the front of the cabinet underneath the operation surface to create the exhaust that travels out of the facility. The air sucked in functions as a shield, preventing possibly polluted air from returning to the operator.
Furthermore, according to the exhaust system and the method of work (recirculation of exhaust air), Class II BSCs have been further divided into 5 different kinds: Type A1, Type A2, Type B1, Type B2, and Type C1.
Let's take a brief look at them.
a. Type A1
The pollution is split right above the workstation and blends with the intake air in the type A1 cabinets, which have a minimal intake velocity of 75 feet per minute. The combined air is then sent back into the cabinet via a duct system. After that, the air may be recirculated upon traveling through the HEPA filters, or it may be expelled out of the cabinet, also after passing through a HEPA filter. Because working with harmful chemical chemicals requires this type of cabinet, it is rarely generally used.
b. Type A2
A baseline inflow velocity of 100 feet per minute is required for type A2 cabinets. Type A2 BSC air enters the container through the front aperture in Class II, which protects the operators. The inflow air is mixed with the countercurrent air (from the top of the cabinet) and goes through the front intake grille before splitting over the workstation.
The downflow HEPA filter recycles and pushes roughly 60% to 70% of the polluted air back into the workstation in the cylinder, whereas the expelled HEPA filter exhausts the residual 30% to 40%. If dangerous, unstable chemicals are utilized in the cabinet as well as microbiological operations, emissions must be vented into the air via the primary exhaust duct. A2-type cabinets are also not widely used due to the risk of hazardous chemicals being discharged into the atmosphere.
c. Type B1
Type B cabinets vary from Type A cabinets in that they regulate the flow of dangerous vapors using a solitary airflow system. The polluted air is sent to the exhaust system in Type B1 cabinets, whereas the air between the controller and the workstation blends with the inflow and is redistributed. To preserve the environment, the exhaust air from the facility should be routed through HEPA filters. The polluted air is released out of the facility through a specific exhaust duct in these cabinets. In Type B1 cabinets, 40% of the air is recycled back, while the other 60% is expelled.
d. Type B2
The air is sucked in from the front entrance of a Type B2 BSC, much as it is in Type A cabinets, forming an air shield to prevent the controller. Air is also brought in through a hole in the top of the cabinet, which feeds the cabinet's downflow of air. After passing through a HEPA filter, the air is evacuated completely through with a dedicated duct system with an exhaust fan motor. As a result, the air leaving the plant is disinfected before being discharged into the environment. The benefit of this system is that poisonous vapors produced in the cabinet are removed without recirculating within the BSC. In a Type B2 cabinet, every one of the polluted airflow (100%) is outwardly discharged, which implies that the air brought into the cabinet is exhausted into the environment.
As a result, neither inflow nor downflow air is recycled inside the B2's airflow system.
These cabinets are ideal for jobs involving the discharge of chemical vapors while none of the air is recirculated. Type B2 cabinets, on the other hand, are costly, therefore they're only used in toxicology labs where chemical safety is critical.
e. Type C1
The functioning mechanism of Type C1 cabinets is identical to that of Type B cabinets, however, they are meant to reduce operating expenses and increase laboratory flexibility. These cabinets operate on a single-pass airflow system, which involves mixing upflow air with downflow air split into columns for recirculation.
A secondary fan draws air from above the workstation, and the polluted air is exhausted through a HEPA filter in the exhaust pipe.
The atmosphere, the operator, and the workstation or biological substance are all protected in this manner by the cabinets. Type C cabinets vary from Type A cabinets in that they have a solitary airflow system that does not exchange the airflow.
Biological safety cabinets Class III
Ultimately, Class III cabinets are surrounded but ventilated leak-tight cabinets in which all air entering or leaving the facility passes through a HEPA filter. Rubber gloves are linked to the device and supplied with the cabinets used during cabinet operations. As a result, these cabinets are often known as "glove boxes."
The cabinet even contains a transfer room where goods can be sterilized before leaving the glove box. Even though the gloves limit the operator's hand motion inside the cabinet, they prohibit contact between both the controller and the specimens. Dual HEPA filters or HEPA filters combined with cremation are used to purify the exhaust air.
These cabinets are suitable for all four levels of biosafety (1, 2, 3, and 4). However, under Biosafety Level 4, these are perhaps the most critical for handling biological materials. They're usually made to order for particular laboratories, with laboratory equipment installed inside. Every one of these structural and architectural aspects offers optimal protection against excessive group 4 microbial pathogens for the driver, the surroundings, and the specimen.