Checking CFM Of A Dust Collector

[Doug Walls]

I consider a 3 hp 14" impeller to be the minimum cyclone with 15" and 5 hp a more safe bet.

Although it sure would be nice to have a larger DC!

Currently with only a 40-amp 220 supply to my two car garage, I'm sort of limited as far as power goes.

( I'm a numbers guy )

Here's some numbers for you!

5hp. Rotary Phase Converter FLA 14.8
2hp-3ph. Dust Collector FLA 5.2
2hp-3ph. Dewalt Radial Arm Saw FLA 5.0

I've never actually tried running all three of these together yet! But in theory it should work?

Figuring that the RPC idler motor should probably never draw it's rated FLA (except for start-up)
it should give me a little wiggle room.

Although math was never really my favorite subject! Using the FLA of 25amps listed above, And figuring that the 3 separate power lines are being generated by the two regular 220 volt input lines.
Working with the numbers, The square root of 3 (1.732) X 25Amps = 43.3 amps.

Doug

[Matt Mattingley]

Although it sure would be nice to have a larger DC!

Currently with only a 40-amp 220 supply to my two car garage, I'm sort of limited as far as power goes.


Here's some numbers for you!

5hp. Rotary Phase Converter FLA 14.8
2hp-3ph. Dust Collector FLA 5.2
2hp-3ph. Dewalt Radial Arm Saw FLA 5.0

I've never actually tried running all three of these together yet! But in theory it should work?

Figuring that the RPC idler motor should probably never draw it's rated FLA (except for start-up)
it should give me a little wiggle room.

Although math was never really my favorite subject! Using the FLA of 25amps listed above, And figuring that the 3 separate power lines are being generated by the two regular 220 volt input lines.
Working with the numbers, The square root of 3 (1.732) X 25Amps = 43.3 amps.

Doug

Doug, I am not so much a numbers guy, but I’ll play... First, do you really have 220v in MI??? Please test! With picture please.

Is the RPC considered a motor or generator under the NEC?
2hp + 2hp (3ph)=4hp. 3ph.
4hp A (3ph) at V/1.73= ?
I would be interested to see a clamp on metre “read” prior to 40 amp circuit showing amp draw, with RPC, DC & RAS all on line with picture.

Remember I am not a numbers guy. But... I am a picture guy.

[Doug Walls]

Doug, I am not so much a numbers guy, but I’ll play... First, do you really have 220v in MI???

The power here is generally referred to as 110/220, But the actual voltage is usually slightly above 120 and 240!

Here's the power reading at my RPC.

Doug

[Doug Walls]

Is the RPC considered a motor or generator under the NEC?

I don't know for sure, But being it "draws" power to create the third leg I'm guessing it's considered a motor?

I would be interested to see a clamp on metre “read” prior to 40 amp circuit showing amp draw, with RPC, DC & RAS all on line with picture.

Well that's probably not going to happen for a while yet! I need to finish running the conduit & outlets from my RPC, Probably a project for this spring.

For now I'm mainly interested in getting the DC set-up & installed!
The DC will be going in the corner of the garage & I'm thinking of trying to partially enclose it to help quiet it down a little.

Doug

[Matt Mattingley]

Thanks Doug. Almost everywhere in North America it is a split Phase 120/240+-5% residential.

You’re 40 amp circuit will be just fine. This is not a clamp on metre but a metre that I have on the wall just for quick reference. The numbers are very close to my clamp on.

Hopefully the pictures don’t get jumbled.
I started the 5hp RPC(disregard the small amperage read on the three phase meter. There’s a small transformer that’s online)
Then 1hp mill
Then 1 hp grinder
Then 1.5 hp bandsaw
Then half horsepower bandsaw
Then 2 hp grinder
Then 1hp hydraulic pump

Nothing has load on it. All fed from 40 amp 240 V circuit.

0BA8B150-116C-40AD-8850-A05A6FA0FF10.jpgEF3C0CF6-F61A-41F5-B9CC-869CDFDA3DFD.jpgF2DA5ADE-E554-4A00-BF2E-8F176FE59C02.jpg1575BE32-BB2E-4D67-BF5F-3FC56E8376C1.jpg571C323E-DD8D-46D0-A11F-794B70707A9E.jpgC44FECED-9E35-424C-BE00-F145A89B85F5.jpg125F67BF-5E50-43A9-B1D3-48D19B73F610.jpg

And here’s a picture of my big 4hp disc sander online (by itself with the 5 hp RPC).
0D8F399F-3C18-45B4-A9A9-60B61DB08162.jpg

[Ole Anderson]

Not looking for lab grade equipment or results. Here is what I use: Here I am measuring 570 cfm at the inlet of my Rockler DustRite connector. 6016 fpm on a 4.12" opening. I was reading 7" WC at the inlet to my 2 hp SDG.

[Larry Frank]

Fan anemometers used like that are very inaccurate and over rate the cfm.

[Ole Anderson]

Fan anemometers used like that are very inaccurate and over rate the cfm.

Any data to back that up and to put a number to accuracy range or are you repeating what someone else said? Probably not any less accurate than the fan curves supplied by the manufacturers.

[Peter Christensen]

Any data to back that up and to put a number to accuracy range or are you repeating what someone else said? Probably not any less accurate than the fan curves supplied by the manufacturers.

It was stated in the paper I linked in post #27.

[Larry Frank]

I have posted on here the variation that I measured with a fan anemometer at the end of a 4" duct. I have measured mine with a hot wire anemomete and posted curves for it.

I absolutely am not just repeating what someone told me. I actually did the measurements.

As for the mfg curves... There are some that I do not trust. However, I have taken the time to measure my dust collector and find the mfg curve to be reasonably accurate. I have also read the procedures that some mfg have used and they are reasonable. I have also taken the time to compare some of the mfg curves to those done by Wood Magazine and again find that some mfg data is pretty good. Some not so good and an exaggeration. You need to read the fine print about how some of the max flows are measured.

So, what have you done to research the accuracy of curves or are you repeating what others have said.

I have done my research and studies and confident in my methods and results. I use my own data and curves to monitor and improve my system.

[John K Jordan]

...I have done my research and studies and confident in my methods and results. I use my own data and curves to monitor and improve my system.

Larry, I can add that your posts on these things have always been obviously well-researched and complete. I appreciate the time you've put into testing and verification and your willingness to share your experience with we-the-clueless!

JKJ

[Ole Anderson]

I have posted on here the variation that I measured with a fan anemometer at the end of a 4" duct. I have measured mine with a hot wire anemomete and posted curves for it.

I absolutely am not just repeating what someone told me. I actually did the measurements.

As for the mfg curves... There are some that I do not trust. However, I have taken the time to measure my dust collector and find the mfg curve to be reasonably accurate. I have also read the procedures that some mfg have used and they are reasonable. I have also taken the time to compare some of the mfg curves to those done by Wood Magazine and again find that some mfg data is pretty good. Some not so good and an exaggeration. You need to read the fine print about how some of the max flows are measured.

So, what have you done to research the accuracy of curves or are you repeating what others have said.

I have done my research and studies and confident in my methods and results. I use my own data and curves to monitor and improve my system.

Larry, thank you, you answered my question. I must have skipped over post #27. I did look at that and came away with the conclusion that the high speed fan anemometer used in the research overstated flow in 4-6" ducts by about 20%. As far as fan curves, I used the American Woodworker Magazine 2008 article as as somewhat of a benchmark when comparing dust collectors prior to my purchase. The Wood magazine article came out just after my purchase. While not lab conditions, the tests were conducted in a consistent manner between the different dust collectors and therefore had validity in my mind. I did compare their results with a three different manufacturer's published curves, and IIRC some were within 20%, others well outside of that 20% number. Having trouble finding that article at the moment. Oneida had two different fan curves for my 2 hp SDG at the time. The one they settled on agrees fairly closely with my measurements, of course that is based on my anemometer flow results.