Myth Busters: Common Myths about Fume Hoods

For today’s article, I’m taking an inspiration from this very popular science entertainment television program Myth Busters. I will try to debunk common myths about fume hoods and hope to keep some BAD practices into rest.

Photo Courtesy of Esco

Myth 1: You can use your fume hood as a storage space for volatile, flammable, or noxious chemicals when an appropriate storage cabinet is not available.

Fact: You can use your hood to keep chemicals during an on-going analysis, but fume hoods are not designed for permanent chemical storage. Items placed inside the fume hood can interfere with the aerodynamic flow of the air, causing turbulence inside the hood and contaminants to be draw out of the hood into the room. 

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Myth 2: A fume hood can be used as a waste disposal mechanism (e.g., for evaporation of chemicals).

Fact: Fume hoods exhaust vapors out into the atmosphere untreated, so it is inappropriate to use a fume hood for waste disposal.  Don’t do further damage to our environment. Please follow proper waste disposal mechanism.

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The "Shut the Sash" campaign above is courtesy of Esco, taken from their facebook account

Myth 3:  Fume hood sashes should not be shut all the way down even when no one is using the hood.

Fact: Fume hoods are designed for their sashes to be shut all the way.  The airfoil sill at the base of the hood will still allow for air to be pulled into the fume hood even with the sash fully closed. Shutting the sash down keeps the barrier between you and the contaminants inside the hood. Plus, it saves you energy!

   

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Myth: When working with highly dangerous materials, the higher the face velocity the better.

Fact: While it is important to have a face velocity between 80 fpm and 120 fpm, a higher face velocity will actually make the fume hood less efficient. High face velocities can create eddy (turbulent) currents that will allow for contaminants to be drawn out of the hood into the room and increase the worker’s exposure. The key here is to always have your hood’s face velocity checked by an expert. Recertify your hood for performance at least once a year.