This is a simple flow bench. Anything may be used to power it. A Shop Vac works fine. I found a centrifugal blower that runs on 24 volts that works well.

 

Both boxes must be sealed except where indicated.

 

The sizes are unimportant.

 

The plan shows a 3/8" throttle shaft but a 1/2" is better.

 

While this may be painfully obvious. The test piece must be sealed tight against the inlet hole.

 

Wire open anything that might close during a test. If this happens, the vacuum cleaner portion of this device will empty the monometers of colored water and spray it on the ceiling at an astounding rate. Another problem is that when you go into the house to shower and take off your new tie-dyed Tee shirt, your wife will see you covered in red and pass out.

 

If you need to know actual CFM data, an HVAC man can stop by and test various restrictors over your test hole that you have made up, and label each test piece with its CFM. A number of aluminum washers with different sized holes works for this. Actual CFM is seldom needed. Mostly, "is it better" or "is it worse"

 is what you want to know.

 

The test box needs to be leveled precisely before each test, because the top monometer reports the outcome of each test, and it is nearly horizontal to start. (like a bubble level).

 

Data is free and unrestricted.

 

Lynn E. Hanover