Measuring Airflow for a Dust Collector | Static Suction & Air Velocity

[@robertnicholson7733]

I have used U tube manometers many times in the past, mostly to do with automated musical instruments. My advice is to add "catcher" jars on each end of the manometer before you get to the device under test. This ensures that you DO NOT fill whatever you are measuring with coloured water or end up with coloured water all over the floor if measuring pressure. The easiest catchers are screw top jars with two nipples in the top and with a capacity much greater than the amount of liquid in the manometer. This will save much repair work and perhaps reduce the spouse irritation factor slightly.

[@GlennFrazeeYT]

Good tip, thanks!

[@shawnmurray7232]

your anemometer is most likely maxed out.... that style usually has a maximum air speed recording capability of about 5400 - 5900 ft/min +/- 10% You're also holding it backwards.... the arrow, and your air flow should be going in the same direction.

[@chrisansari]

I checked your channel but couldn't find part two of this video. I'd love to see a follow up showing what actions you took based on your measurements. Punching your numbers into a calculator I found, your 5000-5400 ft/min airflow in the 6" duct translates into 982-1060 CFM - is that right? Would/should you take the airflow and pressure measurements at the same location?

[@GlennFrazeeYT]

I haven't gotten around to Part 2 of this yet, but it's in the works. Yes, that would be around 1,000 CFM. The measurements I took for this establish a baseline for design of the system.

[@builder4112]

Great video and thanks for the tips.

[@heydoyourhomework]

I know the anemometer part was must illustrating your technique for measuring and not taking a measurement (the unit was turned off and airflow was backward). I am interested in where you learned the technique of using Averaging and moving it around the opening. TIA.

[@GlennFrazeeYT]

Mostly from Matthias Wandell's videos on similar topics.

[@ScottysVise]

In your case with the 5" piping, how would you determine the cfm using the fpm results?

[@GlennFrazeeYT]

Figure out the area of the duct (A = pi/4 * d^2), so for 5" duct, 19.6 in^2 or 0.136 ft^2. Multiply that by FPM, so 5000 fpm * 0.136 ft^2 = 680 CFM. The are also duct calculators online to automate this sort of thing.

[@arcadion448]

@@GlennFrazeeYT, the weird part is why use the 6" duct in the first place? As you mentioned, HF's dust collector comes with a 5" inlet and CFM is restricted by size. Expanding it from 5" to 6" doesn't improve performance. So why not just test with a 5" duct?

[@GlennFrazeeYT]

I'll eventually be upgrading from this Harbor Freight dust collector to something more powerful, so I'm piping larger duct in anticipation.

[@markkoons7488]

Where's part 2?

[@GlennFrazeeYT]

Forthcoming

[@FrancisoDoncona]

All those numbers were with a new clean filter and no dust build up, kind of useless as the numbers are going to get worse.