Recommended CFM's

[Sheila D.]

What is the recommended amount of CFM's for a ventilation system regarding the fan?

[Dale M.]

The recommended values are 125 cfm for every square foot of "face opening" for a open hood...

If you are using a fume "cabinet" (hood+sides) I believe you can get by with 100cfm per sq-ft of face opening...

The "face opening" is height x width for a cabinet or width x depth for simple hood...


As a example on a 24 x 30 inch fume hood....

24 x 30 = 720 square inches

720 sq-in / 144 = 5 sq-ft

5 sq-ft x 100cfm = 500cfm

but if its a open hood its:

5 sq-ft x 125 = 625 cfm

Funnel systems are a bit different, the exact values have not been really defined as exact as a hood, but a 6-7 inch duct system with about a 8-10 inch square (or round) funnel seems to need about 350-400 cfm (minimal) to function effectively...

Dale

[Sheila D.]

Thanks Dale,I was hoping you would pop in on this question!