Biological Safety Cabinet vs Laminar Flow Hood

When working in laboratories, it is important to ensure a safe and clean environment. Biological safety cabinets and laminar flow hoods can be used to achieve this. While they seem similar, their functions, applications, and design principles are different. This article offers a comprehensive comparison between both pieces of equipment, outlining their purposes and advantages. By understanding these differences, you can confidently choose the right equipment for your specific requirements.

What is a Biological Safety Cabinet?

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Biological safety cabinets (BSCs) are also known as biosafety cabinets. They are environments suitable for the use of infectious materials as risk of contamination is reduced. The primary goal of a BSC is to protect you from biologically hazardous or infectious samples. Biosafety cabinets have different classifications: Class I, Class II, and Class III. All provide user protection, but Class II and Class III shield samples from contamination. Class III biosafety cabinets also form a barrier between the user and the specimen. An example of a Class III biosafety cabinet is a glove box.

Biosafety cabinets generate laminar air flow in the workspace and use HEPA filters to filter outgoing (and in some cases, incoming) air flow. In Class I BSCs, air is drawn in through the front panel and exhausted through a HEPA filter into the external environment. However, for Class II, approximately 70% of filtered air is recirculated back into the workspace, while 30% escapes through an exhaust HEPA filter. These filters remove infectious particles and animal or plant matter from outgoing air, making it safe for human exposure. The recirculated air also creates a sterile environment within the workspace. Biological safety cabinets do not protect lab users from exposure to chemicals or gases.

What is a Laminar Flow Hood?

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Laminar flow hoods (LFHs) are designed to provide a sterile environment for sensitive experiments. There are two types of laminar flow hood: vertical and horizontal. The differences between these configurations are the placement of the filter and the direction of air flow within the hood. Horizontal air flow provides the highest level of contaminant removal, whereas vertical air flow is more compatible with bulky equipment.

A key difference is that LFHs provide little user protection compared to BSCs. Even in vertical laminar flow hoods, which have additional protective measures, contaminated air is released back into the lab without filtration. It is important that you do not handle any infectious or harmful material inside a laminar flow hood.

Using the same filtration methods as biosafety cabinets, laminar flow hoods provide a highly sterile environment. They also tend to be lower cost. When conducting non-harmful biological experiments and preparation, such as media preparation, an LFH is the best choice.

Laminar Flow Hood vs Biosafety Cabinet: Making the Choice

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There are some similarities between a laminar flow hood and a biological safety cabinet. Yet, it is important to understand the properties of each to decide which is best suited to your needs.

This table provides a detailed comparison between the two. The primary purpose of a biological safety cabinet is to protect users from infectious materials. A laminar flow hood is primarily used for safeguarding samples from contamination. Both use HEPA filters, but they serve slightly different functions: the BSC filters both incoming and outgoing air, while the LFH focuses on filtering incoming air to remove particulates and contamination.

	Biological Safety Cabinet	Laminar Flow Hood
Primary Purpose	To protect user from infectious material	To protect samples from contamination
Filtration	Uses HEPA filters used to filter both incoming air and outgoing air (Class II) Uses HEPA filters used to filter both incoming air and outgoing air (Class I)	Uses HEPA filters used to filter incoming air, reducing particulates and contamination in workspace
Types	Class I Class II Class III	Vertical Horizontal
Protection Provided	User protection from infectious material Sample protection from contamination (mainly Class II and Class III)	Sample protection from contamination Highest level of sample protection with horizontal laminar flow hoods
Weaknesses	Does not protect user from chemical or gaseous contaminants. Should not be used with volatile or flammable chemicals Sterility of environment will vary based on fume hood classification	Does not protect user from chemical or gaseous contaminants Should not be used with volatile or flammable chemicals Does not protect user from infectious samples
Can be used for	Processes and experiments using infectious materials	Non-harmful processes, such as media plate preparation or working with DNA

Biosafety cabinets are defined by classification: classes I, II, and III. Only Class II and Class III emphasize protecting samples from contamination. Meanwhile, the LFH is available in vertical and horizontal configurations, offering two directions of laminar air flow.

An important distinction is that laminar flow hoods provide no user protection from infectious materials, while biosafety cabinets do.

Neither unit can protect you from chemical or gaseous contaminants, so volatile or flammable chemicals should not be handled in either set up. These materials should only be handled in units with a barrier between the user and materials, such as a glove box.

In terms of application, biological safety cabinets are suitable for processes involving infectious materials. Laminar flow hoods are ideal for non-harmful processes, e.g., for media plate preparation or if working with DNA.

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