The Difference Between Fume Hood and Biosafety Cabinet

Fume hoods and biosafety cabinets are specialized types of laboratory equipment. While both devices are similar in their primary purposes and design, there are differences in function, operation, and other factors. 

Level of Protection

The first type of ventilation device protects a user from inhaling toxic or volatile chemicals. It also serves as a physical barrier between the materials and the laboratory, which eliminates the risk of chemical spills, runaway reactions, and fires.

There are different types of hoods, which are designed for different kinds of protection: 

  • General purpose, benchtop hood;
  • Perchloric acid – Includes built-in water wash down systems to prevent explosive perchlorate salt deposits;
  • Radioisotope – Protection from radioactive materials;
  • Acid digestion – Made of acid-resistant materials and is suitable for high service temperatures;
  • Floor mounted – Allows to transfer equipment and materials into and out from the hood.

Slightly different from a fume hood, a biosafety cabinet protects users, products, and the environment. Here is a more detailed rundown of the protection specifics:

  • Class I cabinets work with biosafety levels 1, 2, and 3. It offers moderate product protection as unsterilized room air is drawn over the work surface.
  • Class II cabinets are also suitable for levels 1, 2, and 3. It provides enough protection to work with infectious agents and tissue culture.
  • Class III cabinets are used for working with very high-risk biological agents and characterized by biosafety level 4. All materials are decontaminated when entering or exiting the cabinet.

Operating Principle

Most fume closets are designed to operate as bypass hoods, which ensures continuous airflow into the work surface with the sash closed. This way, a user is not exposed to toxins coming out of the air exhaust system.

There are different kinds of bypass hoods, such as auxiliary air, high-performance, and reduced air volume hoods. These vary in sash settings and hood-airflow conditions.

As the air enters a BSC, the device uses HEPA- and/or Carbon-filtered unidirectional airflow to remove contaminants. The airflow is combined with suction below the working surface to prevent unfiltered air from entering the space. 

Plus, the same kind of filter is used to remove airborne contaminants coming from inside of the cabinet. This way, operators and the environment are protected in addition to the product.

Materials

When used appropriately, the first type acts as an effective device for containment of the following agents:

  • Hazardous chemicals
  • Volatile liquids, dust, and mists
  • Radioactive materials
  • Odor and gases
  • Aerosols
  • Flammables

However, there are some limitations. For example, it’s ineffective for working with pressurized systems, micro-organisms, highly hazardous substances, and some other chemicals.

Depending on a particular class of cabinets, this equipment can be used for different materials. Examples of research materials that can be used in a BSC include infectious microorganisms, viruses, bacteria, pathogens, contaminants, and other hazardous particulates. Overall, it allows for the safe handling of different kinds of materials but only according to the specifics of each cabinet class.

Possible Uses

A hood can act as a suitable containment device for various settings. Although they are not limited to examples below, here are the most common uses:

  • Laboratories
  • Educational facilities
  • Forensic laboratories

BSCs are used in research, clinical, industrial, and pharmacy settings, such as: 

  • Life science research
  • Cell culture processing
  • Other applications where protection of the user, work product, the environment, and mitigation of cross-contamination on the work surface is needed.

For both a fume hood and a biosafety cabinet, there are requirements for safe use. Those rules should be followed in all the mentioned conditions. For example, it includes not placing chemicals or equipment inside that are not currently needed, blocking off the exhaust slots, preparing a plan of action for emergencies, such as a power failure, etc.