How To Use A Fume Hood

Fume hoods are designed to keep laboratory professionals safe while working with hazardous materials. They filter the air to prevent the inhalation of toxic particles that can lodge in the lungs and cause serious health implications. 

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For fume hoods to provide protection, users must follow basic safety practices. No matter how well a fume hood is designed, it won’t be effective unless proper laboratory safety measures are taken. 


Before Using A Fume Hood

Familiarize yourself with the chemicals. When working with hazardous materials, you should make sure you know the potential safety hazards. Read the Safety Data Sheet (SDS) and follow the safety precautions.

Note the nearest exit, emergency eyewash, and fire extinguisher. Make sure the pathways to these areas are unobstructed.

Check the fume hood certification sticker. Fume hoods should be inspected once a year. The certification sticker lists when the hood was last tested and its average face velocity. The average face velocity ranges from 100 fpm to 120 fpm. Typically, general-use fume hoods are set at 115 fpm.

Ensure the exhaust is operating properly. A fume hood’s main job is to exhaust hazardous vapors and fumes out of the area. 

  • Check the baffles to make sure they are not obstructed. 
  • If the fume hood has an airflow monitor, check the monitor’s status to ensure proper functioning. If you ever suspect changes in airflow while working, take a break to check things out.

Assure all sashes, interior baffles, and panels are in place.

  • Vertical Rising Sash Hoods: Locate necessary equipment and materials at least 6 inches within the hood and then lower the vertical sash to 18 inches.
  • Horizontal Sliding Sash Hoods: Locate necessary equipment and materials at least 6 inches within the hood. Check that horizontal sashes are in place. Four-foot hoods need one sash and six-foot hoods need two sashes. Position the sliding sash between the operator and work in the hood.

Wear appropriate protective gear. You may need additional safety gear depending on what materials you’re using. For example, splash goggles, gloves, and a full face shield may be needed for acid testing. In the case of unplanned spills or fires, users will be protected from serious harm if they are wearing the proper safety gear. 


Properly Using A Fume Hood

All procedures that include the use of volatile materials should take place inside of a fume hood.  Flammable solvents, corrosive acids, corrosive bases, combustible or potentially explosive concentrations of gases, irritating vapors or dust, asphyxiating gases, or open sources of volatile radionuclides are all examples of materials that must be used inside of a fume hood.

Place chemicals at least six inches inside the hood. In the case of an emergency, you’ll need to be able to close the sash quickly. Make sure that nothing is ever blocking this area and that only the chemicals you need for the procedure are inside of the hood. Additional materials will only increase the hazard. Also, placing chemicals at least six inches inside the hood will limit the potential for fumes to escape into the laboratory.

Keep the sash at 18 inches or less from the working surface while using the hood to ensure maximum flow rate and to protect yourself from potential chemical splashes or explosions. The sash works as a safety shield in the case of an explosion. The glass is designed to spider instead of shatter. The sash should be closed when you are not working in the hood.

Keep your face outside of the fume hood. Unless you’re using a walk-in fume hood, your hands should be the only part of your body inside of the hood. The sash acts as a barrier and is there for protection while completing hazardous work. 

How To Use A Fume Hood

Place large equipment on blocks. This will allow air to flow beneath it and enable the fume hood to do its job.

Do not disturb the airflow. Using exterior fans near the fume hood opening may cause airflow disturbances, which will alter the effectiveness of the fume hood. Likewise, walking near the hood opening or making quick motions in or out of the hood may have a similar effect.

Rapid movements can create sufficient turbulence to disrupt the inward flow of air into the hood and may result in worker exposure.


After Using A Fume Hood

Shut the sash. It is necessary to have the fume hood open when working inside of it, but when not in use, keep it closed. When the sash is closed, energy will be conserved.

Place hazardous materials in a closed container. To avoid releasing hazardous materials into the laboratory air, place materials in a closed container before removing them from the hood.

If you’re planning on using a fume hood, familiarize yourself with basic functions and emergency procedures. Note that specialty fume hoods may require additional measures before, during, or after use. Design your experiments to minimize your exposure to hazardous materials and always look for ways to improve safety. When fume hoods are used properly, they help to ensure that laboratories remain safe and effective workspaces for all.

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