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Re: Clamp-Together pipe for dust collection
#dustcollection
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There is a balancing act that goes with low pressure impellers used in most hobby collectors.? Machines range from small jointers with 4" ports to larger shapers with two 5" ports and the cutter creating chips 10-12" away from the port.? The problem is how
to supply both ranges with an impeller designed so people can't overamp the motor when too many gates or too large pipe is used.? My point is that to err reasonably on the side of slightly larger horizontal pipe pays benefits in maximizing cfm as does larger
sweep ells and as little flex as possible.? I've never had dust settle in the horizontal with any system 3 hp or over but I'm not a scientific sample.? Keep in mind that drops should exit the horizontal laterally so dust doesn't settle into the drops nearer
the cyclone but that doesn't work for my shop and I don't find dust in any when the gates open.?
My experience with a 5 hp 15" Oneida impeller is that 8" should only be run a shorter distance to the first drop or two and the highest need machines and then the main should drop to 7".? The 16" impeller can probably handle a longer 8" run but care must be
taken to make sure enough port area is open to balance the velocity into the cyclone.?
I run a high pressure blower on a VFD dialed down because I found it impossible ( or merely difficult for a smart guy ) to get the cfm I wanted on some small machines mixed with the large old machines I also run.? The Oneida smart system does the same thing
on a smaller scale with an automatic speed adjustment to max the cfm in various condition.? If I am using certain machines, I just adjust the hz when I turn on the system.? Dave
From: [email protected] <[email protected]> on behalf of imranindiana via groups.io <imranindiana@...>
Sent: Tuesday, January 19, 2021 9:26 AM To: [email protected] <[email protected]> Subject: Re: [FOG] Clamp-Together pipe for dust collection #dustcollection ?
David,
granted it has been a while, but I do not recall any consideration to horizontal vs vertical in the calculations.
Imran
On Jan 19, 2021, at 12:10 AM, David Kumm <davekumm@...> wrote: ?
I think that generally the 4000 fpm is vertical speed and 3500 is horiizontal.? Another key is to generate the proper velocity into the cyclone inlet to maximize the separation and protect the filters.? Each cyclone has a range for inlet speed that should be
designed into the system.
The Oneida system that is interesting is the smart system which speeds up the impeller to produce more air under pressure.? I think John here has one.? Oneida uses a good quality Baldor motor with a larger frame than CV but their regular 5 hp systems run a 15" impeller similar to the CV 1800.? The Max boosts that with a 16" impeller.? I don't know if CV went to a larger frame motor on their metal cyclone.? The weight of the motor on their 1800 and max was a limiting factor and why they went with a smaller frame.? A DC motor works hard and given a choice, I'd prefer the larger bearings and shaft but then I like the CV cyclone design better than oneidas. Oneida uses a cast AL impeller, CV uses steel.? Filters are also rated for cfm per sq ft so you need to pay attention to that.? CFM at the pressure your system runs at is what I consider most important.? Filtration quality of spun bond, Nano, or HEPA differs but it is the air that doesn't make it to the filters that hurts you.? The filters that minimize pressure drop and maximize cfm beat filters that are a point or two higher in MERV rating IMO.? Most important, don't take my opinion, do your own research. Dave From: [email protected] <[email protected]> on behalf of imranindiana via groups.io <imranindiana@...>
Sent: Monday, January 18, 2021 11:11 PM To: [email protected] <[email protected]> Subject: Re: [FOG] Clamp-Together pipe for dust collection #dustcollection ?
Bird,
The risk of going too big is drop in air speed required to carry chips. IIRC, 4000 ft/min is the goal for the main duct.
So in designing the DC system one is trying to minimize the overall resistance so that adequate CFM is available at the machine while ensuring that the air speed does not drop below minimum requirement.
Imran
On Jan 18, 2021, at 10:32 PM, Bird Cupps <birdc@...> wrote: ?
On the subject of dust collecting, I have quite a bit of 4¡¯¡¯ spiral pipe if anyone is interested. If I remember right, Archarya is in Hawaii, so that¡¯s probably not going to work to get it to him.
Is there any harm in sizing up ducts even if you don¡¯t need it? I did some calculating and figured I needed a 6¡¯¡¯ line but I have 7¡¯¡¯ and 8¡¯¡¯ pipe on hand so figured I¡¯d use that. I picked up a dust gorilla cyclone at an auction and it has an 8¡¯¡¯ entry, so
I need to get to 8¡¯¡¯ at some point.
Bird Cupps
Mount Horeb, Wisconsin
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