Confused: Anemometer, FPM, Bill Pentz, drops etc
#21
(11-20-2022, 10:36 AM)jteneyck Wrote: 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.

Hey thanks guys for all the valuable feedback.

My main challenge, as I mentioned before, is upgrading with 86" high ceilings and still being to vent outside.  So many cyclones come with very integrated filters, which don't help for venting outside.
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#22
(11-20-2022, 11:17 AM)davco Wrote: Hey thanks guys for all the valuable feedback.

My main challenge, as I mentioned before, is upgrading with 86" high ceilings and still being to vent outside.  So many cyclones come with very integrated filters, which don't help for venting outside.

Outside venting will give you the highest CFM possible.  I don't see the ceiling height being a limitation for outside venting with that DC.  Just make gentle sweeps from the DC outlet to a convenient spot on the wall.  

Filters are a loser for CFM.  Even new you will get less CFM than venting outside.  As they load up the CFM drops off as the backpressure increases.  

John
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#23
(11-20-2022, 01:35 PM)jteneyck Wrote: Outside venting will give you the highest CFM possible.  I don't see the ceiling height being a limitation for outside venting with that DC.  Just make gentle sweeps from the DC outlet to a convenient spot on the wall.  

Filters are a loser for CFM.  Even new you will get less CFM than venting outside.  As they load up the CFM drops off as the backpressure increases.  

John

I'm already vented outside with this DC, I just wanted to upgrade it, but the options are limited.
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#24
I have no idea if this would work for you, but at one time I considered putting a box in the ceiling between the trusses that would allow the DC motor (I have a CV) to stick into it providing more clearance to the floor. If you have a garage shop or maybe a detached shop it might allow you to do what you want. In my case I would have framed it in and insulated it but still allow space for air to cool the motor. We moved and i didn't have that problem in my next space.
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#25
(11-20-2022, 03:19 PM)fredhargis Wrote: I have no idea if this would work for you, but at one time I considered putting a box in the ceiling between the trusses that would allow the DC motor (I have a CV) to stick into it providing more clearance to the floor. If you have a garage shop or maybe a detached shop it might allow you to do what you want. In my case I would have framed it in and insulated it but still allow space for air to cool the motor. We moved and i didn't have that problem in my next space.

86" ceilings with 9" joists, gets me to 95", one inch shy of clearance for a CV1450, the shortest model.
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#26
As others have said, if you have any 90* elbows in your runs, they are killers for air throughput. If you have any and can do so, replacing them with 2 45* turns with the turns a foot or 2 apart should help your current system. That should also make the flow acoustically quieter. If you are tuning your system, you can use a mechanics stethoscope to look for sections that are noisier than other sections. Other than rattles against your wall mounts, the noisy spots are where the flow is being disrupted.

Wrapping joints with duct tape can reduce leaks. That is why it is called "duct tape."
Winkgrin Don't assume that screws are air tight.

Also, if you have multiple connections, then making sure that the ones that are closed are actually air tight will also help a lot. Gates can be notorious sources of leaks.

AHill is right. If the flow in the pipe is laminar, then the flow velocity at the center is twice the average flow velocity. Measuring the flow at an inlet of a pipe will likely be roughly laminar. The flow a short distance into the pipe will be turbulent and the equations get messier than I can remember at the moment. Unless you have a pitot tube type anemometer, you probably can't measure the flow velocity in the middle of a straight run anyway.

Putting a length of the clear plastic 4" dust collection hose in the run will also reduce the cfm through that run.

I have not tried a Super Dust Deputy. I bought a Dust Deputy with plastic bucket. There was enough translucent plastic in the bucket lid that I could see that the vortex section did not even begin to seal against the bucket lid. That thing still sits unused on a shelf in the shop waiting for me to spend the time to figure out how to fix such a poor design/fabrication.

The Oneida website shows the Super Dust Deputy connected to the dust collector and to the run with long loops of the 4" flex hose. Minimizing the the length of that spiral-wire-reinforced hose will help a lot. Even so, a bit longer run is better than 90* sharp turns.
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#27
(11-20-2022, 10:12 PM)iclark Wrote: As others have said, if you have any 90* elbows in your runs, they are killers for air throughput. If you have any and can do so, replacing them with 2 45* turns with the turns a foot or 2 apart should help your current system. That should also make the flow acoustically quieter. If you are tuning your system, you can use a mechanics stethoscope to look for sections that are noisier than other sections. Other than rattles against your wall mounts, the noisy spots are where the flow is being disrupted.

Wrapping joints with duct tape can reduce leaks. That is why it is called "duct tape."
Winkgrin Don't assume that screws are air tight.

Also, if you have multiple connections, then making sure that the ones that are closed are actually air tight will also help a lot. Gates can be notorious sources of leaks.

AHill is right. If the flow in the pipe is laminar, then the flow velocity at the center is twice the average flow velocity. Measuring the flow at an inlet of a pipe will likely be roughly laminar. The flow a short distance into the pipe will be turbulent and the equations get messier than I can remember at the moment. Unless you have a pitot tube type anemometer, you probably can't measure the flow velocity in the middle of a straight run anyway.

Putting a length of the clear plastic 4" dust collection hose in the run will also reduce the cfm through that run.

I have not tried a Super Dust Deputy. I bought a Dust Deputy with plastic bucket. There was enough translucent plastic in the bucket lid that I could see that the vortex section did not even begin to seal against the bucket lid. That thing still sits unused on a shelf in the shop waiting for me to spend the time to figure out how to fix such a poor design/fabrication.

The Oneida website shows the Super Dust Deputy connected to the dust collector and to the run with long loops of the 4" flex hose. Minimizing the the length of that spiral-wire-reinforced hose will help a lot. Even so, a bit longer run is better than 90* sharp turns.

Thank you for all the good tips.
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#28
Didn't Bill post here in the past?

I seem to remember some serious contention in DC threads, maybe on other sites.
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#29
(11-20-2022, 10:12 PM)iclark Wrote: As others have said, if you have any 90* elbows in your runs, they are killers for air throughput. If you have any and can do so, replacing them with 2 45* turns with the turns a foot or 2 apart should help your current system. That should also make the flow acoustically quieter. If you are tuning your system, you can use a mechanics stethoscope to look for sections that are noisier than other sections. Other than rattles against your wall mounts, the noisy spots are where the flow is being disrupted.

Wrapping joints with duct tape can reduce leaks. That is why it is called "duct tape."
Winkgrin Don't assume that screws are air tight.

Also, if you have multiple connections, then making sure that the ones that are closed are actually air tight will also help a lot. Gates can be notorious sources of leaks.

AHill is right. If the flow in the pipe is laminar, then the flow velocity at the center is twice the average flow velocity. Measuring the flow at an inlet of a pipe will likely be roughly laminar. The flow a short distance into the pipe will be turbulent and the equations get messier than I can remember at the moment. Unless you have a pitot tube type anemometer, you probably can't measure the flow velocity in the middle of a straight run anyway.

Putting a length of the clear plastic 4" dust collection hose in the run will also reduce the cfm through that run.

I have not tried a Super Dust Deputy. I bought a Dust Deputy with plastic bucket. There was enough translucent plastic in the bucket lid that I could see that the vortex section did not even begin to seal against the bucket lid. That thing still sits unused on a shelf in the shop waiting for me to spend the time to figure out how to fix such a poor design/fabrication.

The Oneida website shows the Super Dust Deputy connected to the dust collector and to the run with long loops of the 4" flex hose. Minimizing the the length of that spiral-wire-reinforced hose will help a lot. Even so, a bit longer run is better than 90* sharp turns.

I wonder if they changed the design.  I bought one earlier this year and it works great.  I agree that the design could use improvement, but it does seal if the two surfaces are clean.  

John
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#30
On measuring flow, check out these instructions: https://www.woodworkforums.com/f200/draf...ost1932353

Please don't confuse me for someone  who knows  how to do this, but my understanding is that there are a lot of details to take care of when measuring air flow.

I would expect low air flow with a 1.5 HP dust collector and a cyclone.  Cyclones rob the system of static pressure.

On the height of ClearVue, I am in the process of installing a ClearVue.  The overall height is really determined by the dust collection bin.  If you are just 1" short, then you could make or buy a shorter dust collection bin.  I have also read it is possible to mount the cyclone at an angle.   I would call the ClearVue folks and ask about that.

If you have budget for a ClearVue, then another option if your height is limited is a Powermatic PM1900 two bag collector.  You can vent outside by putting it in an enclosure that vents to the outside.  I would skip the cyclone, though.

Oneida has several cyclones that fit in a shorter space.  You can order them without filters if you want to vent outside.   Another option, which is more expensive, out of left field option is the Oneida Super Cell.  That would allow you to keep using your 4" pipe, but I see no way to vent that inside.

Spiral duct work is not some kind of magic, performance improving system.  The pipes are female and the connector are male.  So when you put in any connector, it restricts the pipe by 1/8".  Also, the air will blow against the lip of the fittings.   Metal blast gates restrict the pipe volume even more.  Also, the door to those blast gates don't open all the way.

PVC, on the other hand, has male pipe and female connectors, so the connectors don't limit the pipe diameter.

I have done a lot of dust collector research and it's really frustrating there aren't more straightforward solutions.  Since you are already venting outside, improved ventilation might be the more cost effective solution.

Mark
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