What is a Laminar Air Flow Cabinet.

Laminar air flow cabinets can provide a clean room environment of class 100 and below, which is attained by filtering air through HEPA filters , they can remove particulate matter of dimension 0.3 nm and above with an efficiency of 99.997 to 99.999.Hence an appropriately designed and maintained laminar air flow cabinet can provide a sterile environment for handling material which are required to be protected from getting contaminated and from contaminating other material and personals and environment (to prevent cross contamination ).

Laminar air flow cabinets are used in aseptic transfers  (also see aseptic techniques ) aseptic manufacturing process as well as to facilitate handling of microbiological preparations who’s sterility is required to be maintained, as well as to prevent cross contamination during material handling , critical activities which are likely to evolve dust particles like raw material dispensing in pharma manufacturing process are carried out in a laminar air flow cabinet.

In laminar Air flow bench air is filtered through HEPA filters and blown though towards user with a velocity of 0.45 meters/second (90 feet per minute) across the working table . To minimize the upstream particle load inlet air may be filtered through prefilters first and then blown though high efficiency HEPA filters to remove the particles completely, which results in generation of an uniform and smooth air flow pattern where a layer air flowing in one direction do not cross or diffuse in to path of other layer or in to the other layer maintain a pattern of flow like playing cards moving one over the other, such pattern of air flow is called as laminar air flow, which helps in removing the particulate mater away from the path which are then filtered away in recirculation. In other pattern where all layers flow in a zigzag manner in all directions diffusing in to each such flow of air is called as turbulent air flow, same terminology is applied in describing flow in liquids too.

Laminar air flow cabinets can be designed to provide air flow in horizontal as well as vertical air flow direction, both types has their own advantages; regulatory accepted standard for LAF is NSF49 standard.
Laminar flow cabinets are fitted with a Ultraviolet light lamp to keep the shell and content sterilized (see sterility testing), when it is not in use and ultra violet light lamp is required to switch off during use.Laminar air flow cabinets are built with stainless steel in a manner so the surfaces at all sealing points are smooth with no gaps at joints which might help in accumulation of microbial spores and then contamination.

Apart from pharmaceutical industry laminar air flow cabinets are also used in other industry where a material is required to be protected from getting contaminated with particulate matter example is computer where a small particulate matter on the disk can damage entire disk. Laminar Air flow cabinet is also termed as laminar flow bench , laminar flow closet or tissue culture hood.
Biosaftey cabinets:
Biosaftey cabinets are meant for handling hazardous pathogenic microorganisms, viruses , they differs from laminar air flow bench with respect to air circulation pattern, in laminar air flow cabinets air is filtered through HEPA and it is blown towards user and in biosaftey cabinets air is taken in over sample being handled (inside) with velocity ranging from 100 ft/min and the exhaust air is filtered through HEPA filters, to attain higher level of safety about 60% of air from the rear grille is exhausted and 40% air is recirculated. Biosaftey cabinets can be completely enclosed by providing glove attachment from front side.

Also see Aseptic Techniques followed while using Laminar Air Flow Cabinet


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