A biological safety cabinet may also be called a laminar flow hood or flow cabinet, a flow hood, or laminar air flow hood. These enclosures are specifically designed to create a clean air laboratory environment by removing air particulates through a filtration system.
Laminar air flow hoods are commonly used in medical research laboratories that require specialized sterile work environments. They are also used to protect semiconductor wafers, various sensitive equipment and devices, or bio samples from forms of contamination.
How They Work
Flow hoods are made of seamless stainless steel. No joints, overlaps, or gaps that might potentially harbor spores or contribute to work-zone bacteria build-up are permitted. Air temperature and quality are monitored to ensure the least contaminated air is entering the cabinet system.
The laminar flow cabinet keeps dust, dirt, and contaminants out of the work area by maintaining a continuous wall of fast-moving air around the centrally-located work area. Essentially, room air is pulled in and passes through a pre-filter to remove heavy contaminants such as dust and lint. The air is compressed and channeled through the HEPA filter (High Efficiency Particulate Air filter) bacteria-retentive air filter. The filtered air is exhausted in a steady (laminar) air stream flow (in parallel line fashion) across the work surface. The laminar air flow is a steady, uniform airflow projected over an entire body at consistent velocity.
Cabinet and filter cleaning and housekeeping is essential to ensure the required laboratory/operations sterility levels are achieved and maintained. Cleaning should be routinely performed by all users. It is advised to keep the cabinets running 24 hours/day to prevent contaminants from settling and being circulated when the unit is turned back on. It the unit is shut off for any reason, it should be thoroughly cleaned and allowed to run 30 minutes before using.
Types of Cabinets
There are a variety of different kinds of cabinets such as laminar flow cabinets and hoods and laminar flow booths and benches. Each has its specific pattern of airflow designed for its intended use and purpose. Each type of cabinet ensures a contaminant-free work zone designed to meet specified laboratory or operations requirements.
However, there are two basic types of laminar flow hoods – horizontal and vertical.
The horizontal type cabinet is so-named due to the direction the air comes exits the cabinet.
Air from the room enters the cabinet vertically from above and is sent through the HEPA filter. The processed air changes direction, and is exhausted horizontally through the front of the hood across the work
Vertical cabinets typically provide more operator protection. The vertical type cabinet pulls air downward vertically and sends it through the HEPA filter. The filtered air is then blown from the top of the hood directly down onto the work area, away from the operator. The air is removed from the working area through holes in the cabinet’s base. Hazardous chemicals (i.e.: chemotherapy chemicals) are blown away from the individual working at the hood.
Typically, laminar flow cabinets do not protect the environment or the operator. They are not permitted for use with infectious material.
Laminar flow cabinets are used in a variety of labs involved in medical, pharmaceutical, industrial, environmental, and educational environments. The flow hood filtration system ensures the product, sample, or specimen inside the unit is free of any added matter or particulates.
Scientists examining or experimenting with live cell cultures or microorganisms benefit from bacterial-free cabinet environments. Bio research and experiments such as those performed on anesthetized animals require bacterial-, particulate-, and contamination-free environments where the greatest assurance of sterility and hygiene are required to prevent (surgical) infections.
Laminar flow cabinets are also practical for numerous smaller or specialized applications where a clean air environment may be necessary (i.e.: laboratory electronic devices, semiconductor wafers, etc.).