The biological safety cabinet is an essential piece of equipment for those who work with materials that require contamination control. It protects the operator, the environment and samples during activities involving biological agents, chemical substances or any other sensitive element.
But for all this protection to work effectively, it’s important to understand how the cabin system operates. Understanding the path of the air, the role of the filters and how the equipment is designed helps ensure that it is used correctly and to maximum efficiency.
In this article, I explain objectively how a biological safety cabinet works, highlighting the main elements that make up this system and why it is so essential in technical and laboratory environments.
To begin with, let's look at the operating principle.
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Operation principle
The biological safety cabinet works by creating an isolated work environment in which air is constantly directed and treated to prevent the dispersion of contaminants. The system operates through a vertical or horizontal air flow that circulates inside the cabinet in a controlled manner.
This air is drawn in by an internal fan, passes through high-efficiency filters and is then returned to the cabin or exhausted, depending on the model. During this process, suspended particles are removed, preventing the spread of biological, chemical or toxic agents.
The difference in pressure between the inside of the cabin and the outside environment also helps to keep contaminated air confined. This balance between ventilation, filtration and containment is what allows procedures to be carried out safely, even in situations of moderate or high biological risk.
What about the filtration system with Hepa filter? Let's look at that now.
Filtration system with HEPA filter
One of the most important components of the biological safety cabinet is the filtration system, responsible for retaining microscopic particles that may pose a health risk or compromise the integrity of samples.
The HEPA (High Efficiency Particulate Air) filter is widely used for its high retention capacity. It is capable of eliminating at least 99,97% of particles with a diameter equal to or greater than 0,3 micrometers, such as bacteria, viruses and aerosols.
Depending on the cabin class, the air may be partially recirculated inside the equipment after passing through the HEPA filter, or it may be completely exhausted to the outside environment, also in a filtered form. In both cases, the objective is the same: to ensure that the air entering and leaving the cabin is free of contaminants.
The presence of this type of filter is essential to maintain a safe working environment, especially in activities involving pathogens or products sensitive to contamination.
Difference between air recirculation and air exhaust
The operation of biological safety cabinets can vary depending on the model, especially with regard to the destination of the air after filtration. The two most common systems are: partial recirculation and total exhaustion.
Na recirculation, part of the air filtered by the HEPA system returns to the interior of the cabin, while the rest is exhausted to the environment or conducted outside through a duct. This model is used in class II A1 and A2 cabins, and is suitable for handling materials with moderate biological risk and low presence of volatile chemical substances.
Already total exhaustion, as occurs in Class II B2 cabins, eliminates 100% of the air to the outside environment, without any recirculation. This system is recommended for activities involving highly toxic agents, radioisotopes or volatile products, as it ensures that no contaminants remain inside the cabin.
The choice between a recirculation or total exhaust model depends directly on the type of material handled and the level of risk involved in the process. Understanding this difference is essential to ensure the safety of the environment and the good performance of the equipment.
Integrated protection elements
To ensure operator safety and the integrity of the materials handled, biological safety cabinets are equipped with a series of elements designed to offer physical, visual and microbiological protection.
Among the main components, the following stand out:
- Front window in tempered glass: with a thickness of 6 mm, this visor acts as a physical barrier between the operator and the inside of the cabin. It can have a tilting, guillotine or automated opening, depending on the model.
- Side displays: also made of tempered glass, they allow for better lighting of the internal area and facilitate external supervision of the work carried out.
- Led lightning: integrated into the top of the cabin, it provides uniform and clear light in the work area, with low energy consumption and without generating excessive heat.
- Germicidal (UV) lamp: used outside of operating hours, this lamp helps to disinfect the interior of the cabin, eliminating microorganisms that may have settled on surfaces.
- Silent ventilation system: Asmontec cabins operate with noise levels below 55 dB(A), which contributes to a more comfortable and productive working environment.
- Auxiliary socket (optional): available on some models, facilitates the use of small electrical equipment inside the cabin without compromising the seal.
These elements work together to keep the cabin's internal environment controlled, safe and functional, reducing contamination risks and improving the user experience.
Cross contamination control
One of the main objectives of the biological safety cabinet is to prevent cross-contamination, both between the operator and the materials handled and between different samples within the cabinet itself. This control is achieved through a set of physical and engineering mechanisms.
Continuous, directed and filtered airflow is the main resource used to prevent contaminated particles from spreading. In Class II cabins, the air is directed in such a way as to create a protective barrier between the operator and the work area, preventing microorganisms from escaping or impurities from the external environment from entering the internal zone.
Furthermore, the presence of HEPA filters and the design of the structure, with adequate sealing and pressure differentials, ensure that the air follows a controlled path — always going from the cleanest zone to the most contaminated, with no return.
Regular cleaning of the cabin, correct use of personal protective equipment (PPE) and organization of materials during work are also essential practices to avoid contamination between procedures or products.
When all these elements are applied correctly, the cabin becomes a highly effective barrier against the dispersion of biological agents, ensuring a safe and reliable environment for everyone involved.
Conclusion
Understanding how a biological safety cabinet works is essential to ensure its correct and efficient use. More than just a piece of equipment, it is a protection tool that depends on the proper functioning of the ventilation system, adequate air filtration and operation in accordance with technical protocols.
Each cabin component was developed to meet safety requirements in critical environments, and knowledge about how it works directly contributes to risk prevention and the quality of laboratory processes.
If you are looking for technical support to choose the ideal model or want to clarify doubts about the application of the cabin in your work environment, the Asmontec team is at your disposal.
Contact us with Asmontec and receive specialized guidance for your project.
