4" diameter Thien Separator - is it possible ?

[mws120]

G'Day - I have very limited space and wanted to build a Thien separator...and I had the thought of building one from a 4"(internal) diameter mail tube.  The length is currently 3 ft (but can be increased or decreased), the vacuum hoses are 1 1/4".  I will be using a shopvac 1400w. (I'm not concerned at this point in time about the waste capacity of the unit - I will have minimal waste and it will take me months to fill a bucket)

In theory can such a set up work?  Is the small diameter container workable in terms of particle separation, and if so, do I need to adjust the space between the baffle and lid. 

I did a real rough set up last night and used the "crevice tool" into the side of the tube for the "air in".  The air flow works, but I need to remake the baffle in MDF and (I used fluteboard in my test run and the edges snagged the debris - but it confirmed that the system was air tight). 

I'm willing revert to a conventional bucket/bin system, but it would be so much better for me if I could get a 4" tube Thien separator to work.


Stanley
 

[tvman44]

Would be interesting to find out, I suspect the 4"D will be a little small to be real effective but would like to know if it works. :)

[Holbs]

putting on my Super Internet Know It All Hat..  I couldn't see how this would work.  I believe the science and engineering behind the Thien Baffle (must be...  cool to have something named after you that is all over the world!) is the need of centrifugal force, balanced with gravity, balanced with friction against the wall, balanced with CFM. Well, looking at something nearby that is 4" in diameter around my desk... I would bet the CFM would have to be UltraLow, the arc cutout would have to be UltraThin, etc.   Think of a standard dust devil or dyson vacuum cleaner.  The debris does so many revolutions inside their chambers with no separation.  If you slowed down the CFM to lower those same revolutions, the suction pressure at the end of the hose would barely pick up a cat hair?