Biosafety Cabinet Selection Guide | From Class I to Class III: Customization for Ease of Choice
I. Core Functions
Personnel Protection: Utilizing a highly efficient airflow barrier and filtration system, it prevents harmful aerosols and droplets generated during experiments from spreading outside the operating area, avoiding inhalation or contact with pathogens by operators.
Sample Protection: Provides a clean operating environment, preventing external dust and bacteria from contaminating experimental samples and ensuring the accuracy of experimental results.
Environmental Protection: Exhaust air is filtered through a HEPA (High-Efficiency Particulate Air) filter to prevent harmful microorganisms from being released outside the laboratory and contaminating the surrounding environment.
II. Classification and Applicable Scenarios Based on the protection level and airflow mode, biosafety cabinets are mainly divided into three levels: I, II, and III, with Level II being the most commonly used type in laboratories.
| Level | Airflow characteristics | Applicable scenarios |
| Level I | Outside air flows into the cabinet, while contaminated air is discharged after being filtered by a HEPA filter. | Handling low- to medium-risk pathogens only protects personnel and the environment, not samples. |
| Level II | Divided into subtypes A1, A2, B1, and B2, the airflow consists of "descending airflow + circulating airflow," providing more comprehensive protection. | Mainstream laboratory model, suitable for clinical diagnostics, vaccine development, cell culture, etc., protecting personnel, samples, and the environment. |
| Level Ⅲ | The enclosure is completely sealed, and operation must be performed using long-arm gloves. Both exhaust gas and waste liquid require double filtration. | Highest level of biosafety required for handling highly pathogenic microorganisms (such as Ebola virus). |
III. Key Structure
HEPA Filter: Divided into an supply air filter (purifies the air entering the cabinet) and an exhaust air filter (purifies the air exiting the cabinet), achieving a filtration efficiency of over 99.97% for 0.3μm particles.
Airflow Control System: Maintains a negative pressure environment within the cabinet, forming a stable airflow barrier to prevent aerosol leakage.
Workbench: Made of corrosion-resistant, easy-to-clean material (e.g., stainless steel) for easy disinfection and sterilization.
UV Lamp: Used for disinfecting the workbench before and after operations. Personnel should keep away from the UV lamp when it is on to avoid skin and eye damage.
IV. Usage Precautions
Before operation, the biosafety cabinet should be turned on and run for 5-10 minutes to stabilize the airflow. After operation, continue running for 10-15 minutes to expel residual aerosols.
Items inside the cabinet should be arranged in an orderly manner to avoid obstructing airflow circulation. Experiments should be performed within the effective operating area of the biosafety cabinet, avoiding frequent arm movements.
Regularly inspect and replace the HEPA filter, and regularly clean and disinfect the workbench to avoid cross-contamination.
Flammable, explosive, and radioactive materials must not be handled inside a biosafety cabinet. Specialized protective equipment is required for these materials.
V. Difference between Biosafety Cabinets and Laminar Filters
Many people confuse the two. The core difference lies in the type of protection they provide:
Biosafety Cabinets: Focus on personnel and environmental protection; suitable for experiments involving pathogenic microorganisms.
Laminar Filters: Focus solely on sample protection. The exhaust air is unfiltered and cannot be used for experiments involving pathogenic microorganisms. They are only suitable for clean environments requiring sterile conditions, such as cell culture and aseptic techniques.