planning 2H top hat with rectangular inlet

[benji791]

Hello,

I initially posted in retired2's thread. Following his advice, I start a dedicated thread since my design will be a little bit different.

I've read most of what I could understand already on this forum but as every newbie, I still have a few questions before making the jump.

I'm planning a separator for my 1-1/2HP dust extractor. Unfortunately mine is only equipped with a 4" outlet. So any CFM that I can avoid to lose with the separator is important. With its 11" turbine, it is rated at 700cfm and 40m/s
I plan to use the same design with rectangular inlet and bellmouth outlet + air straightener that retired2.

I also have concerns in footprint for the separator. The height is not such a problem (Probably I will extend it to a 2H design).
I found a those nice barrels that are only 15-3/4" dia with 12-1/2" opening. They are quite beefy with nice handles and locking lid. Note, that I don't plan to use the lid on the picture to make the top hat. It would be only used for transport when needed put it in the car to go to the waste collection center.

The 20" garbage cans that I can find are not so robust or really expensive.

I undertood that the wider the separator, the less SP drop I will get. I also undertood that with 4" inlet and outlet there is a big risk of bypass. But what if my round to rectangular transition is quite long with tall but thin rectangular section (let say 5" x 2-1/2"). I would make the transition part 20" long.
As a comparison I see that the CV1800 cyclone from clearvuecyclones  with its 6" inlet and outlet is 18" diameter but it has a long round to rectangular transition (quite thin but tall at the end rectangular section). Keeping those proportions would mean 12" diameter for 4" outlet and inlet. But maybe in this case, it would be safer to skip the bellmouth and just keep the air straightener.
Maybe also I could offset the inlet to compensate the small diameter.

Are there any things that I missed? Is the top hat so much different from the upper part of a cyclone? Or do you think it could work.


Benjamin.

[alan m]

I have found that those barrels will collapse when used with a shop vac

[benji791]

Hello,

Strange I thought those barrels were more resistant than garbage cans.

[alan m]

the one I used with my festool ct22 collapsed in on the sides. I ended up reinforcing it but it wasn't strong enough.

[benji791]

Here is video I had seen where it is said that those barrels are more resistant than brute cans for example https://youtu.be/NB9kc9pWJp0
That's why I was surprised with your comment. But now I think the reason you had this experience is that you used a shop vac with greater static pressure than a dust extractor.

[alan m]

if you are using it for a low pressure system you will probably be ok.
my ct22 creates a lot of suction