Air Straighteners/Bell End/Neutral Vane for Shop Vac Thien Baffle

[masterelectrician2112]

Hello All,

I am getting ready to build my first Thien Baffle for my garage shop.  All of my tools are mobile, so no need for a large DC system yet.  My plan is to use a large shop vac mounted to the wall with a short length 4" diameter PVC pipe connection on the bottom of the shop vac chamber to the separator under it, which will be hung off of the lid of a 32 gallon clear plastic trash can.  Of course I would block the factory vacuum input on the shop vac.  I plan to use 2" PVC pipe for the separator input and the piping to my work bench and to the middle of my garage ceiling.  I will exhaust air from the shop vac outside through a vent in the wall.

I have been reading a lot of the posts here on best practices, but a lot of what I'm reading is geared towards a DC impeller rather than a shop vac.  Would I see any benefit to a three-vane air straightener on the 4" diameter PVC pipe going into the shop vac chamber?  Would a bell end going into the shop vac chamber have any significant effect?  Should I implement a "neutral vane" on the input for the separator?  I guess the basis of the questions is: Is the airflow of a shop vac motor similar enough to a DC impeller that I would see benefits from implementing design features that I've only so far seen on DC systems?   

Finally, Does anybody see any definite red flags with my system design?

[Kelly Bellis]

I've no experience but am presently working on incorporating a Thien Separator into my shop vac as my first attempt while I learn how Phil's invention works. So my answers shouldn't carry any weight, but here goes anyway. Like you, I question the efficacy of the bell mouth outlet together with the so-called air straighteners in shop vac applications, but I'm still planning on their implementation anyway, in part to see them in action, and after I try and figure out how to make them, which for me is where the fun lies! Doing so probably isn't going to do any harm by including them. I also think many of these principles at play are scalable and could possibly be worth the effort. To prove the theory, I will make the separator's exhaust pipe able to be swapped out between a bell mouth and a straight pipe.

Just curious, what exactly is a large shop vac?

[masterelectrician2112]

Kelly, I think you're probably right.  If you get yours built before mine, let me know how yours works with the "upgrades."

Just curious, what exactly is a large shop vac?

I'm going to be using the Bauer 14 Gallon Wet Dry Vac from Harbor Freight.

[Kelly Bellis]

If you get yours built before mine, let me know how yours works with the "upgrades."

Yes, I will; and likewise, please post some photos and share the results from your own Thien Separator.

[Kelly Bellis]

FYI - I've finally gotten my first Thien Separator assembled inside my old Sears shop vac. Not a total success, nor is it a total failure. It's still in experimental/ test phase. See: The Thien Separator Inside A Craftsman Wet Dry Vac