Duct size help

[Steve Wilde]

I just ordered an Oneida v-3000 cyclone today, and am in the process of laying out my ductwork. My layout is pretty simple overall. Just after the inlet it will branch off one direction to my table saw and router, distance is less than 20 feet with 2 90's. The other branch will make an overhead 180 and a straight run of 30 feet. Along this run I will have 3 drops to my machines. They will all be on mobile bases and will need to be pulled out from the wall to use so I will need approximately 5 feet of flex hose to connect to each machine. The question I have is duct diameter. The Oneida has a 7" inlet so I was thinking 7" mains but I was playing with an online calculator and it said that 7" would be too low of a flow and 6" or 5" would be ok. What do you guys think? I'm going to use spiral pipe too if that makes a difference. Thanks,
steve

[John Lanciani]

I used 6" PVC with my V3000 and get decent results but I have the older steel model with a 6" inlet. I'd imagine that if Oneida upsized the inlet they had a good reason to.

[Ole Anderson]

I have the 2 hp SDG with 7" horizontal mains and 4"-6" drops. Works great. You don't need nearly the air velocity in the horizontal runs as the vertical ones. Stick with 7" and stay away from PVC.

[Bill Adamsen]

I have a 3hp cyclone with metal (Spiral Mfg.) 7" horizontal mains and 4"-6" drops. Works pretty well.

[James Baker SD]

Steve:

Is there a reason you cannot rotate the V-3000 to avoid so many sharp bends coming off the inlet? I am not familiar with the V-3000, but I have a Pro-2000 and was able to assemble it to have the filter and inlet in a position relative to each other that fit my installation space but avoided sharp bend close to the inlet.

James

[Steve Wilde]

James,
My shop is long but narrow. It's 12x48. I plan to have my cyclone at one end and run one long run with three drops along the way. I also want one run to come off right at the inlet and go 6 feet down the short wall to the ground, and then run under my 4x8 out feed table to my table saw and router table, which will be integrated into the out feed table. The inlet to the cyclone is 63" off the floor, and I have 88" ceilings. Due to the height difference I will need to make it bend up to the ceiling anyway, so I thought I could just have it do an overhead 180. I was thinking of having the outlet parallel to the short wall with a wye right after the outlet with one side dropping down to the table saw, and the other doing the overhead 180. Does that make sense? Thanks,
steve

[James Baker SD]

Steve,

Makes some sense but I still cannot picture the 180. I know there are many members here who understand this stuff much better than I do, and you will likely here from them as well. I also had the problem of getting from the cyclone inlet up to the ceiling. I had heard and read (probably here on this forum) that it is best to have a few feet of straight air flow into the cyclone. So I used a piece of straight pipe from the cyclone, then a pair of 45s to angle my way up to the ceiling. Not as clean looking as immediate 90s up to the ceiling, but I was too close to the ceiling to use long radius 90s and I had also heard the fewer bends were better and that long radius bends were better. I lost a little bit of my shop near the cyclone with that approach, but it was off in the corner so I figured it was OK.
James

[David Kumm]

Stay with the 7". Bends cause additional staic pressure and the longer sweep ells and slower velocity helps to increase the cfm. CFM at the machine port is the most important goal. A little slower horizontal velocity won't cause problems. You can always branch off the main horizontally and then down if you are worried that dust will drop into other drops. Dave

[Ian Scofield]

Steve can you draw it? You keep mentioning a 180 and all I hear is your CFM dropping. If you draw a pic we can critique it and give you some feedback.

[Steve Wilde]

This is roughly what I was thinking. The line to the right would go to my table saw and router table, the other would be a straight duct with 3 drops for my other tools. Hope this helps

[Steve Wilde]

Here's another example, this is the picture that gave me the idea.