For those of you who have worked with an industrial hygiene or engineering company involved with sustainability efforts which include adjusting laboratory ventilation, when you have had fume hoods originally set to average 100 fpm face velocity reset to average 80 fpm face velocity, what was your 'fail' point when recertifying? (These are 'standard', not "high performance" fume hoods.)

The original ANSI standard considered any average values between 80-120 a "pass"; obviously while we'd prefer to never deviate downward, there is likely going to be some hood, somewhere whose average reading is somewhat less than 80. I guess I can 'live with' a 5% deviation, but what about a 10%? If you accepted "70" for example, as passing, did you verify that with an ASHRAE 110 smoke test? Or ??? Yes, I know I can go back to the consultants but I have a ton of respect for the technical and real-world knowledge of this group.

I realize that face velocity is just one measure of containment, that capture of vapors depends on a number of factors, etc, and our consultants did perform the ASHRAE 110 tests on several hoods at 80 fpm before all similar ones were set to 80 fpm...I am looking for real-world advice dealing with what I have to work with...

many thanks

Margaret

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