nicely done too
- posted
8 years ago
nicely done too
I see a lot of loose ends there.
I've had centralized dust collection for 20 years. I've had blockages requiring taking it apart to clean it out three times. Now I have mine overhead. I also removed the ground wire running inside the pipes, as those were the cause of the blockage in two of the cases.
those ducts in the floor are 6"
seems like they would be hard to clog
of course anything is possible
The fact that they are 6" is precisely the reason they are likely to clog. The air has more space to fill and would slow down causing more debris to settle. Like silt on the bottom of a river, it can build up and even trap bigger objects.
IMO, if your dust collector calls for 4" duct. Some engineers got paid good money to figure that out, don't try to second guess it.
Something similar happens in waste plumbing. People think if 3" is what's called for, then 4" must be better. Wrong. Waste water can travel faster and higher in 3" pipe, which is better for flushing poo allllllll the way out the drain.
That's like installing drywall on the ceiling of a basement, covering all pipes and electrical. When something goes wrong, have fun tearing it all apart to gain access. Not wise, IMO.
With liquids there must be a 5% drop in a horizontal line as well, I would suspect the same thing is true on a horizontal vacuum line as well. If so, then he is in for big problems unless the entire floor is sloped.
Not trying to argue, but I think that's apples and oranges. Slope is irrelevant to a dust collector system, otherwise how would you be able to run the pipe overhead. The sole energy source for drain lines is gravity, which is why slope is so critical. Too much slope and the liquid outruns the solids. Too little slope and the solid won't run at all. Dust collectors work on vacuum alone until they hit the collection tank.
Well the main reason I was thinking of slope is that even in commercial refrigeration there needed to be a 5 deg (not %,my mistake) whether the line was the liquid or the gas side. In large part due to the oil flow so that the oil that leaves the compressor will return to it. I was just guessing that the same thing should be done to a vacuum line because of the particles of heavier dust chunks would coat the bottom of the lines. But then I could be dead wrong on that when it comes to dust control. :) (5 deg drop in 10 feet, regardless if underground or overhead)
Out of curiosity I did a quick search for installation recommendations from an engineering standpoint and only found concerns for line sizing, ELL's WYE's and proper flowing of the lines. Nothing about the drop, so I am most likely wrong in that area. Yet they do speak of dust fallout in the lines
On 02/21/2016 1:40 AM, OFWW wrote: ...
That's owing to low velocity in the line, not slope. It's keeping velocity up that is so critical in sizing lines; w/o sufficient air volume flow, a larger line will drop material and eventually fill up.
Not necessarily. If he has enough impeller and enough HP it will work.
4" generally chokes systems, so 5-6 is a better choice, but more impeller, and hp is definetly necessary.
Not necessary, this is not a gravity fed egress system.
I think you'll be fine if you make sure you have a powerful system. Don't choke your system down to 4", that will choke the air requried to move the dust.
I would not have had gaps in the floor. I would have sawed a hole and sistered the holes with plywood on both sides to keep the joists one piece. I assume you shorted the joists by using 6" joists. I hope that it works.
No slope needed. Proper size for the vacuum is what is needed, be it 6" or 4" as commonly used in wood shops. At work we move plastic material the same way a DC works. Typical run is 50' horizontal, up 18' vertical up to 200' horizontal, then vertical drop. Slope, sags, dips make no difference if properly sized.
We added another fruit with the compressor thing. :-) A compressor pipe has gas and liquids in it, so they obviously have to accommodate both types of fluid flow.
I may be wrong, but I'm thinking if there are any dust chunks coating the bottom of vacuum ducting, the line it too long for the vacuum or there are obstructions in the line.
In the context of dust collection, I contend that slope is irrelevant.
True. I'm also guessing, as with HVAC ducting, the pipe size in the run, especially with offshoots, has to be calculated to maintain full pressure all along the run.
Are there dust collectors with 6" impeller inputs? Probably.
There is virtually no span to speak of on those joists, so I don't see any problem at all with how it's done, especially when I see them supported at each side of the pipe.
I would, however, suggest diagonal strapping or solid joist blocking near the cutouts in this picture.
How about sewer lines? They clog up and you run a snake. If for some reason this clogs up, which "shouldn't" happen, could he run a snake? Otherwise, I'd want the boards covering the pipe to be removable. That's how I'd do it.
On my system, nothing but fine powder gets to my large pipes and fan, and they will never, ever clog up. I pre-filter everything and coming from the ceiling works fine.
He really needs blocking near the piping as well. Where the runners are cut off.
Sure. They're quite common. Mine has a 6" intake, with a 2x4" adapter on it.
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