Flow Hoods or Fume Hoods – Which Should You Use In Your Laboratory?

Key Points to Understanding Which Laboratory Hood is Right for You

Industrial hoods, like laboratory fume hoods and horizontal laminar flow hoods, permit safe handling of hazardous materials and prevent contamination of highly sensitive materials. They are critical workspaces for protecting workers, protecting products, and protecting the environment. Each type of hood has a particular use for which it is best suited and it is important to know when to use each.

Types of Hoods

There are two main types of hoods, exhaust fume hoods and laminar flow hoods. A few key points can help you understand the differences between them.

Exhaust Fume Hoods

Exhaust fume hoods, also known as laboratory fume hoods or chemical fume hoods, are designed to confine hazardous fumes, vapors, gases, and dusts, and remove them to the atmosphere.

Key Features:

  • protects the user from exposure to harmful airborne chemicals
  • does not protect the product from contamination
  • draws unfiltered room air into the hood from the front face (open side) of the cabinet and exhausts the air through ductwork to the outside of the building
  • commonly used when performing chemical reactions that may spatter or fume, procedures that may create dusts or aerosols, and when handling toxic, volatile, or flammable materials

Laminar Flow Hoods

There are two categories of laminar flow hoods:

  • clean benches
  • biological safety cabinets

Clean benches and biological safety cabinets use HEPA or ULPA filtered air to create smooth, non-turbulent layers of purified air flow that travel uniformly (vertically or horizontally) through the hood. Although both rely on filtered, laminar air flow, each is used for very different purposes. Clean benches are designed to control particulate contamination. Biological safety cabinets, also called biosafety cabinets, are designed to contain biological hazards and control particulate contamination.

Clean Benches

Key Features:

  • protects the product from contamination by the user or environment
  • does not protect the user from exposure to the product
  • available as a vertical or horizontal laminar flow hood, depending on the application
  • commonly used in laboratories, inspection areas, and clean rooms to manipulate non-hazardous products in a clean air environment, such as Class 100 (ISO 5) or Class 10 (ISO 4)

Biological Safety Cabinets

Key Features:

  • Class I
    – protects the user and environment from exposure to products that are classified as biosafety level 1, 2, or 3
    – does not protect the product from being contaminated by the user or environment
  • Class II
    – protects the user and environment from exposure to products that are classified as biosafety level 1, 2, or 3
    – protects the product from being contaminated by the user or environment
  • Class III
    – protects the user and environment from exposure to products that are classified as biosafety level 1, 2, 3, or 4
    – protects the product from being contaminated by the user or environment
  • commonly used in research laboratories and hospitals to work safely with infectious organisms and protect live cultures against contamination

Deciding on the Right Hood

Understanding the differences between the types of laboratory hoods is a good start toward choosing the right equipment for the task at hand. In addition, it is important to gather and evaluate detailed information about the products to be handled in the hood, the purpose for which the products will be used, and the protection that needs to be provided to the user, the products, and/or the environment. With all the information in hand, you will be able to choose the type of hood that is best suited for your use.

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