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11-19-2022, 06:29 PM
(This post was last modified: 11-19-2022, 06:30 PM by davco.)
I bought an anemometer to measure how well my old DC ( Delta 50-760, 1.5 hp ) attached to a Super Dust Deputy is performing.
I measured FPM at each of the 4" drops around the shot ( my straight runs are also 4" ), and it looks like I'm getting roughly 2300 FPM at each drop. I don't think I've ever had any major clogging in my system
over the years, but recently I've been looking to optimize the system without spending too much. I also replaced the filter bag and have it vented outside, which I like a lot, don't have to deal with filter bags etc.
I think my calculation for CFM is also correct, 2300/(2squared*3.1416)=183 CFM at the drops. I'm thinking this performance is probably "meh" at best. I'm thinking of doing a couple of things: replace all my stove pipe straight runs with 4" spiral pipe and compatible fittings and get a better chip bin that I know is air tight.
I thought I'd try these things first, before biting the bullet and upgrading my Dust Collector itself. Thing is, if I upgrade to all 4" spiral and then I go with a more powerful system I may have wished my straight runs were 6", but I think 6" may be too big for my current DC which has a 5" inlet.
Any opinions from the woodnet crowd?
Thanks, Dave
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(11-19-2022, 06:29 PM)davco Wrote: I bought an anemometer to measure how well my old DC ( Delta 50-760, 1.5 hp ) attached to a Super Dust Deputy is performing.
I measured FPM at each of the 4" drops around the shot ( my straight runs are also 4" ), and it looks like I'm getting roughly 2300 FPM at each drop. I don't think I've ever had any major clogging in my system
over the years, but recently I've been looking to optimize the system without spending too much. I also replaced the filter bag and have it vented outside, which I like a lot, don't have to deal with filter bags etc.
I think my calculation for CFM is also correct, 2300/(2squared*3.1416)=183 CFM at the drops. I'm thinking this performance is probably "meh" at best. I'm thinking of doing a couple of things: replace all my stove pipe straight runs with 4" spiral pipe and compatible fittings and get a better chip bin that I know is air tight.
I thought I'd try these things first, before biting the bullet and upgrading my Dust Collector itself. Thing is, if I upgrade to all 4" spiral and then I go with a more powerful system I may have wished my straight runs were 6", but I think 6" may be too big for my current DC which has a 5" inlet.
Any opinions from the woodnet crowd?
Thanks, Dave
I calculate 200 cfm at 2300 fpm through a 4" hose. 2300 x 3.14 x r^2/144 = 200.6 cfm.
Got a fan curve for your current DC? Hard to make any comments w/o looking at that.
John
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11-19-2022, 08:02 PM
(This post was last modified: 11-19-2022, 08:49 PM by davco.)
Thanks for clarifying the formula,
Once I know the CFM at the drops, isn't that enough...just still learning.
Where to look up fan curves?
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Also, keep in mind that the speed of air through any pipe is not the same at the middle vs. the sides. So, max speed at the middle is a false impression of the average speed. Depending on where the anemometer picked up the speed, your average CFM could easily be 1/2 what you've calculated.
Still Learning,
Allan Hill
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(11-19-2022, 09:27 PM)AHill Wrote: Also, keep in mind that the speed of air through any pipe is not the same at the middle vs. the sides. So, max speed at the middle is a false impression of the average speed. Depending on where the anemometer picked up the speed, your average CFM could easily be 1/2 what you've calculated.
and who said it’s not rocket science..
Good conversation , always learning
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My opinion is if you're happy with what you have, stop there. I also think if you spend money on 4" spiral pipe and then change DCs, you will wish you had 6".
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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(11-19-2022, 11:01 PM)Tankwood Wrote: and who said it’s not rocket science..
Good conversation , always learning
Ironically, I work as an engineer for a company that makes missiles.
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Allan Hill
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11-20-2022, 09:47 AM
(This post was last modified: 11-20-2022, 09:51 AM by davco.)
(11-20-2022, 06:29 AM)fredhargis Wrote: My opinion is if you're happy with what you have, stop there. I also think if you spend money on 4" spiral pipe and then change DCs, you will wish you had 6".
What I have now is just OK, could be better. I just fear that if I go to 6" may current DC won't work properly and then I will definitely have to upgrade to a more powerful model.
So far I haven't been able to find one that I could also vent outside with. I wanted a ClearVue, but my garage ceilings are only 86" high.
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(11-20-2022, 09:47 AM)davco Wrote: What I have now is just OK, could be better. I just fear that if I go to 6" may current DC won't work properly and then I will definitely have to upgrade to a more powerful model.
So far I haven't been able to find one that I could also vent outside with. I wanted a ClearVue, but my garage ceilings are only 86" high.
I meant to add that to my statement above, 6" is not going to work well with your collector (an opinion).
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.
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Well the fan curve is not in the manual, so that was of no help. But I found a review on FWW where the author measured a max airflow of 925 cfm. That value is likely at 1 or 2" of static pressure (SP) loss. The inlet on that DC is 5". Typically, CFM is measured 10 pipe diameters from the inlet with a pipe of the same diameter. If so, the DC was pulling air at about 6800 fpm.
You measured 200 cfm (likely less as AHill pointed out), which means the SP was pretty high. You can reduce SP and increase CFM by changing from hose to pipe, eliminating as many elbows and T's as possible, using sweeping elbows instead of 90 deg ones, and increasing pipe diameter. If you could reduce the SP losses enough to get the CFM up to 600 cfm you would have a velocity of 4400 fpm through a 5" pipe. You need about 3500 fpm to transport dust/chips through a horizontal pipe, more for the vertical sections.
So, it might be doable. You would need to determine the fan curve for your DC and calculate the SP losses in your upgraded system in order to know for sure if you will have enough flow at the SP at your machines. It's not all that hard to do. You already have an anemometer. All you need a simple water manometer. With the two you can measure the CFM vs. SP of your DC through a 5" pipe, 50" long with various restrictor plates on the end. The SP vs. calculated CFM you create from those measurements will tell you if it's capable of meeting your needs after upgrade.
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