Maybe OT, but not as much as many.

I have a fairly large centrifugal blower (squirrel cage) & I'd like to know its CFM. It has a well defined opening, so knowing the velocity of
the air is what I need.

I can think of a couple of approaches. The first that comes to mind is placing a surface in the air stream & measuring the force exerted on it. I know that there is a relationship between the air velocity, the surface area and the force (drag), and I could find a formula on the web, but I worry that a little bit of knowledge could be a dangerous thing. I.e., I suspect that this is a complicated subject and an understanding should accompany formula use. But if someone here has the understanding & could give me the right formula, that would be great <G>.

Another approach is to measure the pressure in the stream & derive velocity from that. I think that this would be subject to even more complications than using force, but maybe not. Anyone know? If it's a reasonable approach, what about a formula?

Or, I could get/make a

Advice anyone?

Thanks, Bob

I have a fairly large centrifugal blower (squirrel cage) & I'd like to know its CFM. It has a well defined opening, so knowing the velocity of

I can think of a couple of approaches. The first that comes to mind is placing a surface in the air stream & measuring the force exerted on it. I know that there is a relationship between the air velocity, the surface area and the force (drag), and I could find a formula on the web, but I worry that a little bit of knowledge could be a dangerous thing. I.e., I suspect that this is a complicated subject and an understanding should accompany formula use. But if someone here has the understanding & could give me the right formula, that would be great <G>.

Another approach is to measure the pressure in the stream & derive velocity from that. I think that this would be subject to even more complications than using force, but maybe not. Anyone know? If it's a reasonable approach, what about a formula?

Or, I could get/make a

___really big___poly bag & time how long it takes to inflate. Much too crude for my taste.Advice anyone?

Thanks, Bob