A Question - please help

[JSP]

Please help with my question - I am building a DC system with 6" PVC and have a small steel barrel of about 17" diameter. 3HP blower on system.   With a 6"  side inlet and a 6" outlet on top, will the top hat have enough size - diameter - to operate properly??  Or should I consider getting a somewhat larger drum to build the top hat for?

also, if I stick with the 17" drum, how tall should the top hat be?

:)

JSP

[tvman44]

IMHO you will a larger diameter, like x2.

[BernardNaish]

The Brute bin allows a diameter a shade under 20" and at 30 gallons is about right for many shops. Height is determined by inlet duct size not drum size. You need a rectangular input duct and the height of this sets your top hat height.

Look at retired2's build that you will find here:
http://www.jpthien.com/smf/index.php?topic=563.msg3024#msg3024.

Generaly copy this but use polycarbonate (Lexan etc.) and not acrylic (Perspex, Plexiglass etc.). It is a long thread but well worth reading, might even say it is essential reading.

Some suggestions that a gap could be included under the inlet to reduce any turbulence caused by circulating flow hitting the incoming flow. When this gap is equal to the rectangle height the top hat is called a double height top hat. When equal to rectangle height it is a single height top hat that is known to work well. Hence any gap may not give a huge improvement. Could include a gap equal to height divided by four giving a 1 1/4 TH or by two giving a 1 1/2 TH.

All will become clear as you read more. Hope your build goes well.

[Mike F]

Hi JSP, Although I haven't used my 1.5H design much, I can say that at 400mm (16") it seems to work really well. My 'Brute' like bin is only 450mm (18") diameter so I don't see that there should be a problem with your bin size. It is interesting that Mr Dyson has gone to smaller and smaller diameter cyclones and bunching them together, in his cleaners. I do appreciate that the vacuum cleaner has high velocity, low volume air supply whereas our DC systems tend to use high volume, low velocity but it could be that the smaller diameter may be better at accelerating the smaller particles - hmmm?

I think the general message here is to suck it and see. Whatever you come up with will definitely be an improvement on a DC only solution.

Mike

[JSP]

Thanks guys!  It is my next project.

JSP