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Thien Cyclone Separator Lid Discussion / Re: Introduce yourself...
« Last post by Farmgopher on March 23, 2017, 02:36:35 PM »
Hello,

Just built a Thien Baffle for my Delta dust collector.  Learned a lot from this forum.  Hoping to post some pictures to help other people who are interested in building one themselves.  Thanks
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R2,
On behalf of everyone, thank you for making the substantial effort to preserve your photos on this forum.  A picture is worth a thousand words.
-Schreck

Your quite welcome Schreck, and thanks for your support over the years.  I realized most of my threads would be worthless without the photos, and I didn't want that to happen to a thread with nearly 100,000 views.  Obviously, somebody has found that one worthwhile.
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R2,
On behalf of everyone, thank you for making the substantial effort to preserve your photos on this forum.  A picture is worth a thousand words.
-Schreck
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March 16th and it appears all new photo links are working, that's good news.  Now I have to worry if Dropbox will eventually cut off photo hosting altogether.  Then I'll get to do this all over again!. 

I guess now I will try to find all forgotten photos I've posted in other forums and correct those links.   >:(
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Thien Cyclone Separator Lid Discussion / Re: Reducing cyclone filter clogging
« Last post by phil (admin) on March 14, 2017, 09:23:00 PM »
I agree w/ retired2.  Maybe a better solution would be an alarm or shutoff for the existing system, to prevent it from overfilling.
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Hopefully there will be enough outcry that dropbox will make it at least somewhat easy to maintain the links to pictures.

Well Dropbox has not blinked!  They are dug in.  They don't even respond to account holders, or make any attempt to explain why they are doing this.  "Sorry for the inconvenience" is the most you can get out of them.  So, on 3/15 the lights go out unless you create all new links for every photo.

I've put in a marathon session to find and create new links to my all my photos in the Thien forum.  If I've done everything correctly my photos will continue to display when Dropbox kills all the links to their public folders presumably at midnight on 3/15.

I'm anxiously awaiting the deadline and keeping my fingers crossed.
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Thien Cyclone Separator Lid Discussion / Re: more newbie questions
« Last post by dragonflight on March 11, 2017, 02:21:44 PM »
I just have to add - kids today have no idea how great all this stuff on the internet is. I would have had to spend days looking up stuff in the library to figure this stuff out in my younger days! Now it takes a few tens of minutes to find and read half a dozen references!!!
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Thien Cyclone Separator Lid Discussion / Re: more newbie questions
« Last post by dragonflight on March 11, 2017, 02:15:23 PM »
Retired2,

thanks for your replies and thoughts.
Yes I am set on the rectangular ducts, but you are right it is uncommon territory.
I did some searches and though I give the links you probably don't want to read them but in www.hauckburner.com/pdf/pneumatic%20conveying%20%20%20(GJ74).pdf they mention moving sawdust and talk about moving 30lbs/min  in a 6" pipe! I know it would take me a lot longer than a minute (or even a week!) to generate 30lbs of sawdust. I think we are only moving air and not material!
 a quote from page 2
Quote
Figure 8 shows the friction loss for
various velocities and duct sizes. These resistances are based on standard air. There are no charts
available which list the friction for the various material carrying air flows with varying percentage of
carrying capacities. The best method of determining resistance of air/material mixture is through pilot
plant testing or experimentation. Most writings on this subject however, seem to indicate that selection
based on standard air provides satisfactory performance.
and http://www.sciencedirect.com/science/article/pii/S0301932211002060 talks about simulations and testing on comparing rectangular and circular duct for conveying material
Quote
The particle fluctuating velocities in the pipe are higher than in the channel for all situations, yielding mostly higher wall collision frequencies. As a consequence, in all the considered cases, the pressure drop in the pipe is larger than in the channel, especially for high wall roughness.
I honestly did not read the whole thing, so I'm not sure what was kept constant in the simulations (volume, speed, equivalent diameter ) or they were just testing wall resistance (they major cause of the pressure drop), and as before their concern for wall collisions is with a significantly higher proportion of material/air.

I have - in the past - read about rectangular ducts and Bill Pentz does talk about lined particle board to construct ducts, so I'm confident it is worth the risk/effort - as they say the proof will be in the pudding!

I will be sure to let all know how it works - eventually

thanks
mike
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Thien Cyclone Separator Lid Discussion / Re: more newbie questions
« Last post by retired2 on March 11, 2017, 01:04:37 PM »
I didn't read every word of the two links in your post, but I get the feeling the equivalency formulas are for air only.  Makes me wonder how applicable they are for pneumatic conveying.

The best advice I can give you is to abandon the idea of rectangular ducts.  There is a reason why all your tools transition from rectangular to round!

But since you seem to have your mind made up, make sure it is airtight because you will probably have more seems to seal unless you are going to bend sheet metal.  And if you are going to bend sheet metal, make it strong because it will be much easier to collapse than round pipe in an equivalent gage.
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Thien Cyclone Separator Lid Discussion / Re: more newbie questions
« Last post by dragonflight on March 11, 2017, 12:15:00 PM »
It makes sense I've been told that was where my head was for years!

http://www.engineeringtoolbox.com/equivalent-diameter-d_205.html has the formula
equivalent diameter = 1.3*(H*W)0.625/(H+W)0.25
and http://www.engineeringtoolbox.com/equivalent-diameter-d_443.html some examples.

In the grand scheme of 5% or 10% doesn't make much difference as we are talk 8" vs maybe 6" ducts.

The swirling in a duct is bad and introduces extra losses. Air naturally straightens out over distance in a duct.
Round duct is used because it has less surface area, less weight and cost and in big plants it is custom.

For me rectangular lets me choose arbitrary sizes and is much easier to build custom transitions, corners and hoods.
All my tools have rectangular to round transitions for ducts (except my bandsaw - not sure what I am going to do yet), so even that is easier.

The Cincinatti Fan documentation actually does double the length of vertical sections for SP calculations, but the main reason I mention no vertical ducts is that the target 4000 FPM is based on vertical ducts and a more modest 2500-3000 FPM is generally quotes for horizontal ducts (to keep them clear).

For constant volume the SP loss varies with the 5th power of the diameter of the duct so going from reduces the SP loss greater than 4 times.

Time will tell and who knows the whole thing maybe a bust, but it is pretty easy and cheap to build the ducts and try!

mike
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