Introduction
Definition of a Biosafety Cabinet Class 2
A class 2 biological safety cabinet (BSC II) is an enclosed, ventilated workstation meant to protect both humans and the environment. A Biosafety Cabinet Class 2’s principal function is to establish a physical barrier between the operator and the hazardous chemicals being managed, preventing exposure to harmful microbes. HEPA filters are installed in these cabinets to ensure the elimination of airborne pollutants and the maintenance of a sterile working environment.
Role in Protecting Workers and the Environment
Biosafety Cabinet Class 2 is a type of biosafety cabinet that is critical to the safety of laboratory staff and the environment. It produces a negative pressure condition by drawing air into the cabinet and filtering it using HEPA filters before recirculating or exhausting it. This airflow design prevents dangerous compounds from escaping, so protecting the operator from potential exposure. Furthermore, Biosafety Cabinet Class 2 helps to preserve the environment by restricting bacteria within the workstation and preventing their spread into the laboratory or neighboring regions.
Principle of Biosafety Cabinet Class 2 Operation
Airflow Control Mechanisms and Design
The airflow design and control mechanisms are important to the operation of a Biosafety Cabinet Class 2. To maintain a hygienic working environment, these cabinets use a combination of vertical and horizontal laminar airflow patterns. The airflow is achieved by supplying filtered high-efficiency particulate air (HEPA) air that is directed in a regulated manner to provide a continuous barrier between the operator and the dangerous contaminants. The airflow design guarantees that any possible pollutants are evacuated from the work area quickly, lowering the risk of exposure.
HEPA Filtration and Laminar Airflow
The unidirectional movement of filtered air within the workplace is referred to as laminar airflow, which is a vital component of Biosafety Cabinet Class 2. By reducing the presence of airborne pollutants, this airflow pattern promotes a sterile atmosphere. HEPA filters, which have a 99.97% effectiveness in removing particles as tiny as 0.3 micrometers, filter the air. HEPA filters are critical in preserving the purity of the air within the cabinet by capturing and containing harmful particles.
Types of Biosafety Cabinet Class 2
Class 2 Type A1 Biosafety Cabinet
Features and Characteristics
Personnel protection and environmental control are provided by Class 2 type A1 biosafety cabinets. While the leftover air is expelled, these cabinets recirculate a part of the filtered air back into the workstation. They keep a minimum inward airflow velocity of 75 feet per minute (fpm) at the face aperture, ensuring containment and preventing dangerous chemicals from escaping.
Design and mechanics of airflow
A vertical laminar airflow pattern is used in Class 2 type A1 cabinets. The filtered air is sent downward towards the work surface, taking away any possible pollutants. 70% of the air is recirculated via the HEPA filters, with the remaining 30% expelled via a separate ventilation system.
Class 2 Type A2 Biosafety Cabinet
Features and Characteristics
When compared to type A1 cabinets, class 2 type A2 biosafety cabinets provide a better level of personnel and environmental protection. These cabinets have a minimum inward airflow velocity of 100 fpm at the face opening, which provides improved containment. They have an exhaust system that takes a part of the air from the cabinet and vents it to the outside, ensuring that harmful compounds are safely removed.
Design and mechanics of airflow
Vertical and horizontal laminar airflow patterns are used in Class 2 type A2 cabinets. The filtered air is directed downward and horizontally towards the front entrance, creating a barrier to protect the operator. The HEPA filters recycle 70% of the air, while the remaining is expelled via a specialized ventilation system.
Class 2 Type B1 Biosafety Cabinet
Features and Characteristics
Class 2 type B1 biosafety cabinets are intended to protect personnel while also preventing environmental contamination. These cabinets maintain a negative pressure within the workplace, preventing potential leaks from entering the laboratory. They have an exhaust system that safely takes air from the cabinet and filters it before discharging it.
Design and mechanics of airflow
An exhaust system is used in Class 2 type B1 cabinets in which 70% of the airflow within the cabinet is vented, with 30% recirculated. The supply air is HEPA-filtered and routed downward, while the exhausted air is evacuated safely from the cabinet through a separate exhaust system.
Class 2 Type B2 Biosafety Cabinet
Features and Characteristics
By maintaining a negative pressure within the workstation, Class 2 type B2 biosafety cabinets protect personnel and manage the environment. A specialized exhaust system safely eliminates polluted air from these cabinets, ensuring that dangerous items are adequately controlled. They have HEPA filters incorporated into both the supply and exhaust air streams.
Design and mechanics of airflow
A whole exhaust system is used in Class 2 type B2 cabinets. The HEPA-filtered supply air is routed downward and horizontally towards the front entrance. A specialized exhaust system safely removes the cabinet’s exhaust air, assuring the removal of harmful contaminants.
Class 2 Type C1 Biosafety Cabinet
Features and Characteristics
Class 2 type C1 biosafety cabinets are designed to protect personnel and the environment. These cabinets work under negative pressure to keep dangerous items contained and prevent their discharge into the laboratory or the surrounding environment. They have twin HEPA filters for both the supply and exhaust air streams, adding an extra layer of filtration.
Design and mechanics of airflow
A system comparable to type B is used in Class 2 type C1 cabinets. The HEPA-filtered supply air is routed downward and horizontally towards the front entrance. The exhaust air is carefully extracted from the cabinet via a separate exhaust system, preventing harmful compounds from escaping.
Key Differences Between Biosafety Cabinet Class 2
Airflow Direction and Design
The airflow design and direction of the various types of Biosafety Cabinets Class 2 varies. Type A1 cabinets in Class 2 use vertical downward airflow, whereas type A2 cabinets use a combination of vertical and horizontal laminar airflow. Class 2 type B1, B2, and C1 cabinets, on the other hand, use a whole exhaust system with supply air directed downward and horizontally. These airflow design and direction changes are critical in defining the amount of containment, human protection, and environmental control provided by each cabinet type.
Containment and Personnel Safety
Another important distinction between Biosafety Cabinet Class 2 types is their level of containment and people protection. Class 2 type A1 cabinets offer basic people protection and confinement, whilst type A2 cabinets give enhanced protection and containment characteristics. Class 2 cabinets of types B1, B2, and B3 feature more advanced containment capabilities, with B3 providing the maximum level of protection. Each cabinet type’s level of containment and human safety is determined by aspects such as airflow design, exhaust systems, and filtering processes.
Applications and Environments Required
Based on the amount of confinement required, each Biosafety Cabinet Class 2 type is appropriate for certain purposes and situations. Class 2 type A1 cabinets are often used in research laboratories and teaching institutions for low-to-moderate-risk applications such as routine diagnostics and cell culture. Type A2 cabinets are suitable for comparable uses but provide extra protection, making them ideal for research laboratories, pharmaceutical institutions, and hospitals. Class 2 type B1, B2, and C1 cabinets are utilized in specialized research institutions, biomedical businesses, and pharmaceutical enterprises for moderate-to-high-risk applications such as genetic modification, pathogen research, and work with volatile chemicals.
| BSC Class | Face Velocity | Airflow Pattern | Application: Nonvolatile Toxic Chemicals and Radionuclides | Application: Volatile Toxic Chemicals and Radionuclides |
| II, A1 | 75 | 70% recirculated to the cabinet work area through HEPA: 30% balance can be exhausted through HEPA back into the room or to outside through a canopy unit (Figure 3) | Yes (small amounts) | Yes (small amounts)*b |
| II, B1 | 100 | 30% recirculated 70% exhausted Exhaust cabinet air must pass through a dedicated internal cabinet duct to the outside through a HEPA filter (Figures 5a 5b) | Yes | Yes (small amounts) |
| I, B2 | 100 | No recirculation: total exhaust to the outside through a HEPA filter (Figure 6) | Yes | Yes (small amounts) |
| II, A2 | 100 | Similar to II, A1. but has 100 Ifm intake air velocity exhaust air can be ducted to the outside through a canopy unit (Figure 7) | Yes | When exhausted outdoors (formally B3), (small amounts)** |
| II, C1 | 100 | 30% recirculated 70% exhausted Exhaust cabinet air must pass through a dedicated, internal cabinet duct to the outside through a blower and HEPA filter | Yes | Yes (small amounts)*b |
Biosafety Cabinet Class 2 Installation and Certification
Installation Instructions
It is critical to properly install Biosafety Cabinet Class 2 to ensure its functioning and efficiency. Installation should be performed by skilled specialists that understand biosafety rules and legislation. The cabinet should be located in a suitable section of the laboratory, away from entrances, windows, and high-traffic areas. A sufficient distance should be kept around the cabinet to allow for optimal ventilation and ease of access for maintenance and repairs.
Compliance with Regulatory Standards and Certifications
To ensure its safety and functionality, Biosafety Cabinet Class 2 should meet regulatory criteria and be certified. The requirements for biosafety cabinets are outlined in international standards issued by organizations such as the International Organization for Standardization (ISO) and the Centers for Disease Control and Prevention (CDC). Furthermore, certificates from respectable organizations like NSF International and the European Biosafety Association (EBSA) ensure that the cabinet adheres to established norms and procedures.
References
Chosewood, L. C., & Wilson, D. E. (2010). Biosafety in microbiological and biomedical laboratories. Books Express Pub.
https://www.cdc.gov/labs/pdf/SF__19_308133-A_BMBL6_00-BOOK-WEB-final-3.pdf
https://www.unr.edu/ehs/policies-manuals/biosafety-manual/chapter-8
