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Airflow Patterns in Biological Safety Cabinets and Laminar Flow Hoods

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a month ago
a month ago
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Biological safety cabinets and laminar flow hoods are both protective equipments that are designed to protect a product or an operator from contamination. These are commonly used in manufacturing sectors, as well as medical facilities and research labs. These sectors deal with sensitive materials, harmful chemicals, pathogens, etc. So the biological safety cabinets and laminar flow hoods are both used to offer reliable protection in such cases.

Biological Safety Cabinets (BSC)

Simply put, a biological safety cabinet is a special type of workbench. On the top, a blower with an air filter is present that pushes the air down towards the work surface. The sides of the cabinet are covered, and a front sash may also be present. The continuous flow if downward air has two functions – to push all contaminants downwards and out of the work space and to make sure that air from the surrounding doesn’t enter the work space.

The airflow pattern in BSCs are always vertical and flowing downwards.

Laminar Flow Hoods (LFH)

Laminar flow hoods are also similar to biological safety cabinets in some ways, but they are not the same thing. The similarity is that LFH also has a blower with an air filter that creates a flow of air which blows foreign particles and contaminants away from the work space. But unlike BSCs, laminar flow hoods have two configurations for air flow – a horizontal flow pattern where the air is blown from the back of the equipment towards the front, and a vertical flow where the air is blown from top to bottom.

Air flow pattern in BSCs and LFHs – What’s the difference?

Laminar flow hoods are designed to protect a specimen or product from contamination. The flow of air ensures that any material, specimen or chemical kept in the LFH will be free from contamination. But since the air is pushed away from the workspace and into the environment, so it does not provide safety for the operator and the surrounding environment. This is the case for both horizontal and laminar flow hoods.

Hence, they are not suitable for hazardous materials or toxic gases, as it would be sent straight towards the operator and into the nearby atmosphere.

 On the other hand, Biological safety cabinets provide higher degree of protection to the product, the operator and the outside environment as well. BSCs have a vent at the bottom that collects all harmful particles. The downwards flowing air will push all contaminants and toxic compounds to the base of the workspace and into the vent. So the contaminated air will never reach the operator or escape into the atmosphere.

Thus, they are suitable for biohazardous materials and toxic compounds.


To summarise all that we discussed above,


Laminar Flow Hoods:

- Can have both vertical and horizontal air flow pattern.

- Protect the specimen in the workbench, but push the contaminated air towards the operator and surroundings. The specimen is protected but the operator and environment isn’t.

- Are suitable for materials that must be kept in a clean and sterile environment, but not suitable for biohazardous items.

Biological Safety Cabinets:

- Only have downwards vertical air flow.

- Don’t let the contaminated air flow towards the operator or into the surroundings. Specimen, operator and environment are all protected.

- Are suitable for biohazardous materials and chemicals that emit toxic gases.

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