Laminar flow cabinets are used in laboratories where a working environment which is free of dust, bacteria and other contaminants is necessary to a given experimental procedure. These cabinets are also used in some production facilities and quality control departments where the same sort of conditions are a requirement.
At least within the working area of the cabinet, the equipment in the cabinet prevents external contamination as well as cross contamination from occurring, preserving the integrity of the material being worked with. However, they are not designed to provide protection for the working environment or for the operator; Laminar Air Flow when this protection is desired, biological safety cabinets are used in the place of laminar flow cabinets.
A cabinet is used when the purity of the air in the work area is a concern, but not in applications or environments where the safety of the operator would be put at risk by their inability to ensure the protection of the operator. These cabinets use laminar flow to prevent contamination of materials; a laminar air flow system circulates air in planes which are parallel to one another and greatly reduces the chances of airborne contaminants from affecting the outcome of a procedure or the purity of a product being manufactured in an environment using a laminar flow system.
These cabinets are frequently used in hospitals and clinics, particularly in surgical theaters as well as in pharmaceutical production facilities, laboratories and food processing and preparation applications. The localized control over air purity enabled by these cabinets make them ideal for applications where this is a mission critical factor.
The air circulated in a cabinet with a laminar flow system is first drawn into the top of the cabinet using negative pressure before being sent through a pre-filter to capture larger particles. This air is then directed through a high efficiency HEPA filter under positive pressure. This dual filtration system ensures that the work environment inside the cabinet is filled with air which is sterile and clean.
The parallel air flow provided by laminar flow cabinets is unidirectional and at a speed which prevents unfiltered air from the surrounding environment from entering the cabinet. This also ensures the quick removal of any particles which are made airborne as the result of work underway inside. The cabinet is enclosed as well to provide additional protection from contamination; a measure which is considered to be necessary for the protection of the very sensitive materials usually tested or manufactured in these environments. Among other materials, biological samples, semiconductors and microchips are often worked on in these cabinets, which provide an environment similar to a clean room.
Both horizontal and vertical laminar flow cabinets are available, with different configurations in use for the specific space and airflow requirements of specific applications. Some cabinets also feature germicidal UV lamps which sterilize the cabinet and its contents before and after use; a safety and quality assurance feature common in life science laboratories where cross contamination between biological samples is an important concern.