Shut the Sash
By: Lee Stone

Most laboratory workers understand the importance of keeping the fume hood clear of unused materials, keeping materials at least 6 inches inside the hood, not blocking the baffles and keeping the sash below the certification height when in use, but they fail to recognize the importance of keeping the sash closed when not in use.

A closed sash on a fume hood serves the following purposes.

• When the sash is closed it acts as a barrier between you and the materials that may be in the hood. The sash is made of tempered glass and can offer added protection from shattered glass, chemical spills, and vapors which will remain contained in the hood if the sash is closed when an “accidental event” occurs.
• In case of a power outage or hood ventilation failure, chemical vapors will not back up into the laboratory. If there is an accidental or emergency shut down of the fume hood ventilation system a closed sash will help contain vapors in the hood. Never open a fume hood if the ventilation system is not operational.
• Energy savings. Fume hoods actually account for much more energy use than you might expect. Most fume hoods at IUPUI operated on a "variable air volume" system, which means the speed of the air circulating into the hood remains constant regardless of how high the sash is open. Since the air flow will remain at a constant rate, the volume of air pulled through the hood will vary depending on the size of the face opening. Therefore, the larger the fume hood opening, the larger the volume of air circulated through the hood, and since most of this air is being removed from the laboratory it is heated or cooled air that must be replaced by outside air that has been heated or cooled. If the fume hood is not in use, keeping the sash wide open wastes $1,500 or more in energy costs per year per hood.

To remind laboratory workers to shut the sash we will be posting the yellow sticker seen below on our fume hoods.

Look for the new sticker on your hood and remember to “Shut the Sash”. Closing the sash for safety and energy savings is a very healthy habit to develop.