> In the (unlikely) event you have 4 ACH with the hoods off then the ducts will act as stacks and suck in air from the outside.
There are many class labs that are likely to have ACHs that are much higher than 4, if there is more than one hood per 500 square feet of floor space. I agree that turning hoods off entirely may not be appropriate, but if the chemicals are not being used and appropriately stored, there are likely to be opportunities to reduce air flow in many hood settings. We have reduced our air flow in our hoods significantly in our two class labs.
- Ralph
Ralph Stuart, CIH, CCHO
Environmental Safety Manager
Keene State College
603 358-2859
ralph.stuart**At_Symbol_Here**keene.edu
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