Mounting motor upside down and to the side (Plenum)

I'm pressed for height in my shipping container workshop and noticed this method of mounting the blower while re-reading Bill Pentz' build instructions which might allow me to use a larger collection bin than the piddling little box I'll currently have to use and empty every 2 minutes.

It's the alternative method on the right that I'm interested in...assuming it doesn't mess with the efficiency of the unit.

What the heck is that plenum thing at the top?
And what sort of dimensions/radius do I build it to for a 20" cyclone and 12" blower opening?

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Originally Posted by RedShirtGuy

I'm pressed for height in my shipping container workshop and noticed this method of mounting the blower while re-reading Bill Pentz' build instructions which might allow me to use a larger collection bin than the piddling little box I'll currently have to use and empty every 2 minutes.
It's the alternative method on the right that I'm interested in...assuming it doesn't mess with the efficiency of the unit.

What the heck is that plenum thing at the top?

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It's to transfer the air from the top of the cyclone to the impeller.
I reckon it would have to mess with the efficiency - see below, but folks (like me) with height restrictions may not have a choice.

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And what sort of dimensions/radius do I build it to for a 20" cyclone and 12" blower opening?

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I imagine the plenum should have at least the same cross sectional area as the outlet of the impeller but I would make it at least as tall as the outlet and as wide as you reasonably can.

I'm not sure if BP has built and tested that setup, but given it effectively adds a 180º bend to the air flow it has to add some resistance to flow especially as it is just a box and not a smooth transition. A better way would be to use large radius bends but that would require more height which defeats the purpose of that design.

Whatever you do make sure you get the motor/impeller/cyclone rotation all going the same way.

Perhaps open up the roof of the container and put a elevated section in to allow for the cyclone. People modify containers all the time for stuff like this.

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Originally Posted by BobL

Whatever you do make sure you get the motor/impeller/cyclone rotation all going the same way.

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While it makes a difference it is not as big as you might expect but it is markedly noisier with a higher pitched sound attached to it. Getting the DOR correct was something that mystified a few people before we came up with a good way to describe it. I started putting stickers on the fan housing towards the end of my tenure with CV, that worked well and I believe CV now do that to all units after I discussed it with them. The best description is that the fan must turn with the full weld that attaches the blades to the base leading and the stitch weld trailing.

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Originally Posted by Chris Parks

While it makes a difference it is not as big as you might expect .

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That's good to know.

I was mainly going on previous experience with blowers and what BP had to say about this.

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We can build our cyclones from these plans with the inlet on either the left or right, but you should build your cyclone for the best match with your impeller. The direction the air turns inside the cyclone is set by the inlet. For motors smaller than 2 hp turning a smaller impeller you can put the inlet on either side because my testing only showed about 0.1 amp difference with no measurable airflow difference. When I upgraded from the smaller blower to the larger 5 hp with a larger impeller I was stunned at the difference. The bigger impellers with larger motors generate a really fast moving spiral of air that needs to be turning in the same direction as the impeller, or the impeller has to overcome that direction of spin. This quickly spinning air when it hits the blower can cost up to 1 hp of overall performance if it is not turning in the same direction that the impeller is rotating. . . . . . .

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I am going from my own personal experience and others that i know of who have had the DRO wrong. My apologies for no scientific basis, just observation on my part.

Thanks guys. It seemed like a wierd way to pull air from the cyclone, but there ya go :)

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Originally Posted by BobL

Whatever you do make sure you get the motor/impeller/cyclone rotation all going the same way.

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Oh Lordy yes...that's how I completely stuffed up my first build (Big Red) a few years ago. I'm concentrating intensely on that part this time :B

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Perhaps open up the roof of the container...

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I've been thinking that's what I might end up doing. Previously I was restricted (Dad wouldn't let me) from modifying the container, but given all that's been done to it now I'm sure one more hole won't matter :)

I could throw the whole motor/blower assembly on top of the roof and gain even more collection space at the bottom. It'd also make it easier to sort out how to vent the dirty air.

Something I'm definitely keeping in mind too.

The cyclone works when placed on an angle effectively making it shorter and wider. You could keep the motor and impeller inside with the end of the cyclone outside and the barrel below it. Upside is no dust when switching bins. Downside is knowing when the bin is almost full. There does come a point where it makes the most sense to have the whole machine outside.

Pete

Why don't you put the cyclone outside in a shelter and run the ducting through the walls. I used to supply CV's to a company who did exactly that, they were building mobile laboratories using 20 foot containers and that is exactly what they did. I am reluctant to post a photo because when I asked they regarded it as their copyright as I wanted to use it on my website.

Yeh, I'd much prefer to do that but I don't have any suitable space for it around the outside :(

PM me your email address and I will send you a picture of what they did. here are some pictures of a low ceiling height set up....

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Thanks. That setup is pretty nice.

I'm getting set on just poking the blower through the roof now. Easy, free (with the materials I have to hand) and a gain of at least a couple of feet. Still not a perfect setup, but more than adequate for this little shed monkey :)