4" vs 6" DC piping

[glenn bradley]

Just a real world report here . . . The collection at my tablesaw, router table, jointer, and bandsaw all improved drastically when I went from 4" to 6" duct. This was nothing you had to measure; it was very obvious. I run an aging 2HP Grizzly cyclone G0440.

[Curt Harms]

I think you would get better performance with 6" duct and a Thein baffle plus a cartridge filter in your existing dust collector than with a separator with 4" ductwork.

That's what I have. I went with 6" in part because I have no choice except to use flexible hose, all my machines are mobile. I'd read somewhere that a 6" corrugated hose will move about the same volume of air as 4" smooth piping. I have a '2 hp' 12" impeller single stage DC with Thien baffle in the funnel and 100% spun bond cartridge filter. The machine connections are 4" but transition to 6" as soon as practical. The only time I've had material settling out of the air stream is if I restricted the airflow at the collection point using a 2 1/2" hose. I could always tell because the next time I had the blast gates fully open I'd hear a small 'slug' of material hit the impeller. It wasn't enough to cause an issue but I could hear it. I can avoid that if using a 2 1/2" hose by opening another blast gate a little admitting enough air to keep the velocity up.

[Raif Harik]

Well Robert, You, very kindly, asked for it. Here is a terrible drawing with rough est. of distances of my shop. There are four machines a mitersaw, a router table, a table saw, and a lathe. the measurements are roughly between fittings, so the straight pipe lengths. If you are interested I could ... maybe do better, or at least get closer to real measurments.
I look forward to hearing thoughts.
Thanks.
Raif
DC_Layout.jpg

[james manutes]

A 2 HP single stage w/ bags isn't going to give you the CFM your hoping for . A cannister filter will give you a bump up in performance , if you go any form of a 2-stage collector . Also , all separators aren't created equal. If you have the budget for a Dust Deputy , why consider a Thien bafflle ? Try to design your system to get all thats possible w/ that blower . I'd consider a " shop built " cyclone - up grading the impeller if possible . I'm not sure if you could get a bigger impeller in that housing . Look into it .

[Frank Pratt]

Okay, I would definitely go with 6" duct because you will at some point find that the 2 HP DC is not doing it for you. Then you'll have the infrastructure in place for a bigger DC. If dust settles in the duct because of low air velocity then you just clean it out periodically.

[Kevin Jenness]

You owe us a photo of the tree.

[Jim Becker]

Dust collectors work by moving large volumes of air at a particular velocity. Within the ability of a given blower to move air, smaller ductwork cannot move as much air as larger duct work. The difference in area/volume between 4" and 6" duct is "a lot". So if your unit has the capacity to use 6" duct, using smaller, particularly for a main run, compromises performance. 6" main with 5" and 4" drops is very common for the size of many folks workshops for that reason.

[Raif Harik]

20220305_095219.jpg20220305_122946.jpgAs requested by Kevin, a picture of the tree. I have not sealed the roof yet, clearly. But my geologist friend has explained to me that the way the environment will change in central Texas is that it will be hotter and drier. So, who knows maybe I wont need too.
I also included a picture of a nifty little remote control switch I installed. The existing one was super hard to turn on or off.

[Bill Dufour]

I would guess the horizontal upper runs will be fine with 6" duct. The verticals can probably be 6" and have fast enough flow to make the chips rise up against gravity. Worst comes to worst 6" horizontal main line and 4" drops.
Bill D.

[Randall J Cox]

I use a 1.75 hp powermatic motor and fan, into a Onieda super dust deputy with a 5" inlet and 5" tubing all over my 3 car garage shop. It all works well. Have a large .5 micron Wynn cartridge filter on top. Added a magnahelic guage with tubing sealed into top of cartridge filter to tell me when back pressure was building in filter. Usually only have to clean filter cartridge once every 2-3 years. Most of tubing is hvac big box stuff but for long ceiling runs I used nice smooth 5' thin wall pvc. Not easy to find but I live in an agricultural area and its avail. I've also tried to open up most machines from 4 to 5" for good dust collection at source. Randy

[Mike Kees]

If you want a system to perform well you need to determine needed CFM for each machine. Start there. Every diameter of pipe is only capable of "x" CFM ,this is how you determine branch drop diameters to your machines. Once that is figured out work back to the collector figuring out diameter of main trunk to work well. Last step is what size and CFM /static pressure is needed for your collector. Starting with a collector and then going what size pipe do I need is going about this backwards. Air handling systems has a bunch of this info on their website. Sandor Nagalanzky (last name spelled wrong) wrote an excellent book called "woodshop dust control ". This book is slightly dated but he explains everything I just summarized and much more. I have also read Bill Pence's website extensively. Bill seems to have simplified things(systems wise) to make it easier. "Just buy a Clearview and run 6'' pipe " . Which will work very well for most small shops, because the diameter is large enough for ample CFM for most machines backed by a very large blower with a very efficienct cyclone.

[Ole Anderson]

I have also read Bill Pence's website extensively. Bill seems to have simplified things(systems wise) to make it easier. "Just buy a Clearview and run 6'' pipe ".

I remember Bill saying the 7" size is ideal, but if you go with PVC, 6" is the way to go. I went with a 7" lock joint steel main duct on my 2 hp Super Dust Gorilla. (Gosh, how many times have I said this over the years??)

"Because air is near incompressible at the low pressures we use in dust collection, we end up with the pipe diameter and resistance controlling our air volume. This is just like water. We open and close a valve to regulate how much water comes out of our faucets. To support the minimum 1000 CFM we need for fine dust collection, we need to upgrade our 4" ducting and tool port connections to a total area the same as the opening area of a 7" duct or we must use a bigger more powerful blower that generates the pressure to pull ample air through a smaller duct. "

[glenn bradley]

2HP cyclone, 6" duct, 2 - long 90's, 3 - 45's, 40-odd foot run, t-shirt.

New Shop (371).jpg