If it were me, in a research environment NOT in California (since their regulations specify face velocity), I want the hood to demonstrate capture and containment of vapors. This can be checked using smoke inside and around the sash edge, and one of the following:

1.       For semi-quantitative, more objective data: A photoionization detector and an organic solvent such as acetone, hexane or whatever the PID will respond to. IF you use glacial acetic acid (below) and the PID, you'll need an 11.6 eV lamp. Check the concentration inside and outside the hood.

2.       For a qualitative check, a watch glass and a few mL of glacial acetic acid or concentrated ammonium hydroxide will provide ample evidence of containment. I've never encountered a an individual that cannot detect the odor or glacial HAc or ammonium hydroxide.

It's been my experience that hoods with less than about 70-75 fpm; likewise hoods greater than about 230 fpm will fail as well.

My 2-cents. Your mileage may vary.

Harry