Calculating Exhuast Flow for Fume hoods and BSC

[tj00343]

Hey guys,
I'm doing a university project where I am designing the hvac system of a lab.
I'm having trouble figuring out how I'm supposed to calculate the exhaust flow required through fume hoods.I know this depends on the type of hazard that is being dealt with in the Lab but my knowledge of the actual processes that will be taking place is limited at best.I downloaded a book (ASHRAE Laboratory Design Guide) and I can't seem to find anything specific in there.That's the best recourse I could find.
Any insight into the topic would be appreciated.
Thank You

 

[russ_watters]

For the most part, you select the hood based on the size requirement of the lab users. After that, the full-flow airflow is what the standard and manufacturer says (it's typically 105 fpm across the face).