Top Hat Design Guidelines

[Tacuabe]

After reading nearly every post in this forum, I found most newcomers ask the same questions over and over again.  So I prepared a rough sketch with the design constraints resumed in a simple form. I hope you find this useful when tackling those new projects. It's a single sheet in .pdf.

[alan m]

great job.tthanks for taking time and making the effort

[300e]

Phill this one could be a sticky, it is a good reference for people to start building.

[phil (admin)]

Phill this one could be a sticky, it is a good reference for people to start building.

If only the distance between the top of the baffle, and bottom of the inlet, was shown with a gap and shown as being variable.  You don't have to hug the bottom of the inlet with the baffle.

[sparkysmart]

Hi Phil,

I'm new to the group although I've been lurking and of course building and testing the Thien Baffle for some time.  In reading "all" of the posts on the site I keep hearing that the ultimate separation is with a true cyclonic separator that utilizes a long rectangular inlet going to an air ramp which in turn goes in to a 1:1.64 cone.  So with those elements in mind I keep hoping to increase the separation of either my Thien Top Hat or Thien Baffle built in to a standard, as in Harbor Freight, dust collector.

My next evolution was to install an air ramp in my existing setup, any thoughts?

The next concept that I'd like to explore is inclining the sides of the dust collector so that both gravity and centrifugal force would influence the movement of the particulate in the direction of the baffle's slot.  Again, any thoughts.

Here are cross sectional sketches of both concepts.

I've also thought about streamlining the entrance in to the centrifuge of the top had configuration by utilizing a larger radius on the entrance, a sketch of that is also attached.

[Tacuabe]

Hi Phil!

Have seen your comment on my .pdf sketch of the baffle design guidelines. I seem to have missed what you point out and would willingly correct the sketch accordingly.

What happened is that, from my perusal of most of the forum posts, no one mentioned the fact that the  chamber height could be variable and higher than the inlet diameter/height. Although there are many examples of that, there are also many which use a chamber of the same height as the inlet.

In view of this, I have a question of my own: How does this parameter affect the baffle operation? This may also lead to a suitable comment to add to the guidelines.

Thanks for your comments!

[DarthVader]

so does making the separator taller have any advantages? i know most cyclones are taller than the inlet size in the upper section...

[Bulldog8]

When I built my separator, I made the chamber height 1/4" taller than my inlet pipe with the outlet inserted to a distance equal to 1/2" its diameter. However, there are a few threads that addressed shop situations that produced more than a normal amount of fines. (generally a drum sander or the like)

Phil said that increasing the chamber height, keeping the inlet at the top and then dropping the outlet further into the chamber would help separate fines. For example I currently have a 6 1/4" tall chamber, with my outlet inserted 3". If I increased the chamber height to 12 inches, I would insert the outlet to 9".

I haven't experimented with this yet, but it's been on my "to do" list.

[phil (admin)]

When I built my separator, I made the chamber height 1/4" taller than my inlet pipe with the outlet inserted to a distance equal to 1/2" its diameter. However, there are a few threads that addressed shop situations that produced more than a normal amount of fines. (generally a drum sander or the like)

Phil said that increasing the chamber height, keeping the inlet at the top and then dropping the outlet further into the chamber would help separate fines. For example I currently have a 6 1/4" tall chamber, with my outlet inserted 3". If I increased the chamber height to 12 inches, I would insert the outlet to 9".

I haven't experimented with this yet, but it's been on my "to do" list.

The first issue is that, if the baffle hugs an elbow from the inlet, a lot of debris will be caught between the elbow and the baffle.  So I suggest probably about 1/2" to 1" between the bottom of any elbows and the baffle.

If using a side inlet, there is nowhere for debris to catch, so less of a concern.

In terms of separation rates, improvement can be had sometimes by increasing the distance above the baffle, while also extending the outlet port accordingly.

[transplant_wi]

Hello all - another newbie question related to the design guidelines. How important is it that the outlet project below the underside of the lid, towards the baffle?

I am part-way through my build and currently have the outlet flush with the underside of the lid, but can fix it easily.

Thank you.

[phil (admin)]

Hello all - another newbie question related to the design guidelines. How important is it that the outlet project below the underside of the lid, towards the baffle?

I am part-way through my build and currently have the outlet flush with the underside of the lid, but can fix it easily.

Thank you.

It is pretty important, in terms of separation rates.

[Tacuabe]

Phil:

I've attached an updated .pdf with revised Top Hat Design Guidelines. Several recent posts (and answers) provided additional info which I tried to reflect in my sketch. I hope it is now usable.

Please take a good look at it. Your comments/suggestions/amendments are most welcome. The idea is to provide newbies with a safe starting point and some indication of possible improvements by experimentation. I know I'd welcomed something along these lines when I built mine.

[phil (admin)]

It looks good, but the outlet tube's height of 1/2 D from the baffle is actually supposed to be 1/2 D from the top.  I suppose some people may wish to make taller separators, which makes stating this relationship a bit of a challenge. 1/2 D from the baffle would be 1.25" for a 2.5" setup, 2" for a 4" pipe, or 3" for a 6" pipe.

So let's actually say the distance between the baffle and the outlet tube should be equal to D of the outlet tube.

[Tacuabe]

Phil:

First of all a small clarification. There is a "D" and a "d" in my sketch. "D" is the diameter of the separator. "d" is the diameter of the inlet and outlet pipes. I presume that you refer to "d" in your comments.

As for the height of the outlet from the baffle, my drawing is based on several posts which I quote:

(4) Anything in the 8-9" is going to be about the same.  If you make the separator tall enough (think a two-story separator) so you can extend the outlet tube below the bottom of the inlet, you will get better fines separation.  Obviously the unit will be larger and heavier, though.

Quote from: alan m on February 02, 2013, 03:46:26 PM
the general rule for the outlet is 1/2 the diameter down but that only applies when the depth of the seperater is the same as the diameter of the inlet. (that also means that it is 1/2 the diameter up from the baffle

that is the key
the outlet pipe should be 1/2the diameter(3" in your case) up from the baffle.


the inlet pipe should be a at the top . that way it has the maximum amount below it to spin around on and seperate.

Exactly.

Alan M. - thank you for your answer.

You say "the outlet pipe should be 1/2the diameter(3" in your case) up from the baffle."

Seeing the walls will be 12" does that mean 3" from the bottom or 3" from the top? Sorry to be so thick......

Thank you.

Howard

3" from bottom, so the tube will extend down approx. 9" from the top.

All of the above refer to questions posed by Howard in Toronto for a proposed 12" high separator with 6" inlet/outlet pipes. I believe my sketch reflects exactly what was suggested to Howard.

However, your comments of today show a different approach to the same problem. Can you please elaborate on this? I'd like to settle this issue.

[alan m]

It looks good, but the outlet tube's height of 1/2 D from the baffle is actually supposed to be 1/2 D from the top.  I suppose some people may wish to make taller separators, which makes stating this relationship a bit of a challenge. 1/2 D from the baffle would be 1.25" for a 2.5" setup, 2" for a 4" pipe, or 3" for a 6" pipe.

So let's actually say the distance between the baffle and the outlet tube should be equal to []1/2D  of the outlet tube.

i think phil means this instead.