# Piping



## djg (Dec 24, 2009)

When I got my Jet DC1100C 1.5 HP dust collector I ran a lot of pipe and Tees thinking it would work properly. It didn't. So I'm rethinking the setup. ROUGHLY, how many feet of 6" dia. pipe can you effectively run off a 1.5 HP DC? Yes I know it depends on other variables like Tees, elbows etc. Maybe some of you have similar setup.


----------



## TomCT2 (May 16, 2014)

various thumb-guides declare a minimum air velocity of 6,000 feet per minute (fpm) for dust/chip collection.
the Jet DC1100C advertises a fan design producing 1,100 cubic feet per minute (cfm)
if you divide the cfm by the duct sq ft (pi*r^2 thing) you get fpm - the theoretical airspeed inside the duct.


the bad news: 1100 cfm divided by 0.1964 sq ft (=six inch pipe) = 5,602 feet per minute air velocity.
below the 'magic' number - probably explains the unsatisfactory set-up - tees/elbows/gates all make it worse.
the 'bigger is better' doesn't work in this situation. 

dropping to a 4" pipe provides 12,605 fpm theoretical and a lot more cushion for friction/leakage losses.


replace the 6" stuff with 4" stuff and enjoy. 

if you're collecting only small chips (helix heads) and sawdust (saws) and using a cyclone separator, use 3"


----------



## djg (Dec 24, 2009)

I was always under the impression that if your main trunk line was too small (4"), it would restrict air flow. I guess velocity is more important than volume of air when it comes to dust collection??


----------



## ducbsa (Jul 6, 2014)

This chart recommends a lower velocity:

https://www.engineeringtoolbox.com/pneumatic-solids-transports-d_134.html

https://www.engineeringtoolbox.com/ductwork-equations-d_883.html

https://www.engineeringtoolbox.com/duct-velocity-d_928.html


----------



## djg (Dec 24, 2009)

Great links. Thanks


----------



## ORBlackFZ1 (Dec 25, 2013)

djg said:


> When I got my Jet DC1100C 1.5 HP dust collector I ran a lot of pipe and Tees thinking it would work properly. It didn't. So I'm rethinking the setup. ROUGHLY, how many feet of 6" dia. pipe can you effectively run off a 1.5 HP DC? Yes I know it depends on other variables like Tees, elbows etc. Maybe some of you have similar setup.



I used a Jet DC1100 for years. You can find more information on what steps I went through to improve the performance here: https://www.woodworkingtalk.com/f32/pipe-diameter-vs-performance-59625/


I would suggest that you find a good web page that has dust collection design on it. Here are a couple:


https://airhand.com/designing/


https://www.oneida-air.com/blog/how-to-select-the-correct-duct-diameter


https://www.oneida-air.com/blog/airflow-vs-pipe-diameter


https://www.pennstateind.com/duct_assist.html


Getting the design correct the first time is tough....


There are a couple of books on dust collection design that are posted in this thread: https://www.woodworkingtalk.com/f32/dust-collection-references-65642/


Eric


----------



## djg (Dec 24, 2009)

Thanks everyone. A LOT of information to read and digest.


----------



## TimPa (Jan 27, 2010)

I go by minimum 4000 fpm air velocity, so I don't think the 6" is an issue, as long as the dc is delivering the advertised cfm rating...


another question would be do you have blast gates on the ends of the branches? the fewer runs you have open at a time the better!


and yes, there is friction from every foot of pipe, and more from elbows, tees, and corrugated type hose - so minimize those.


----------



## djg (Dec 24, 2009)

Yes blast gates at every drop and only one opened at a time.


----------



## TimPa (Jan 27, 2010)

djg said:


> Yes blast gates at every drop and only one opened at a time.


that would result in the advertised 1100 cfm - friction being supplied at one 4" (?) port, which typically needs 390 cfm. the system either has a ton of friction, or maybe you were expecting more, or both...


how far from dc to tool? any other devices on the dc, cyclone, filters, etc...?


----------



## djg (Dec 24, 2009)

I already realized I've got too much piping, etc for toe DC that I have. I was going to draw out my current setup, but that would be moot. So I briefly describe:
The DC is connected to a 6" ell (flex metal dryer vent pipe) to a verticle 6" metal (7'?) and runs into another 6" ell at the ceiling.
The main line is now at the ceiling ans is 6" metal pipe and runs for xx feet.
Off of that, I run 4 laterals:
one 6" 4 feet long; necked down to 4" and then a Blast Gate (BG)
two 4" 7 feet long with BG at end of each.
one 4" 10 feet long with BG at end.
The main is terminated with a 4" BG.


All piping is metal HVAC ductwork (HD) and all seams on pipe, ells and reducers are caulked with Si caulking.
4" plastic flex hose runs to each machine.


Clearly too much.


I plan on cutting the 6" main in half (removing the latter half and 3 laterals).


----------



## Carl10 (Feb 3, 2017)

*DC1100 Piping*

I had the same machine for years with the same delusion of making it fixed and running lots of piping. In my experience and the tests I ran, a 5" duct was the sweet spot for shorter runs. As already mentioned the 4" is too restrictive. Yes of course it works and so does a 6", but the 5" gave the best performance and maintained the best velocity. They are also readily available at big box stores in light gauge and grainger has them affordably in heavier gauge. At your suction level the light gauge is more than adequate. I assume you know the 1100 does not/ can not produce 1100CFM, more in the 700CFM range. So your calculations should start their.

As Eric listed above the Air handling page is a good reference and this chart helps with the CMF/velocity issue. If you look at the 3500/4000 FPM velocity columns (the minimum design level) you will see that you are at the maximum level the 1100 can perform at with out adding all the resistive ducting, ports, gates etc.. Once you add that resistance you drop the velocity below ideal. Dropping to 5" keeps the velocity high and doesn't add the all resistance that a 4" pipe introduces.

Hope this helps. Let us know what you do.

Carl


----------



## djg (Dec 24, 2009)

Thanks everyone. I rework my system (6" piping from big box stores) by doing what I said I'd do earlier. Basically I removed about 13 feet of 6" pipe and 4 Tees and associated 4" flex pipe. Man it sucks! It even sounds better. Haven't hooked up to tools and used yet, but you can tell the flow is much better. The chips ought to fly of the 15" planer hooked to the nearest blast gate (8' from the back wall) with 4" flex hose. The middle blast gate drops directly down t the sander with 4" flex hose. Never was a problem here. The blast gate on the right (4' from the main branch) is for the jointer of the bandsaw. Just use a 4" flex pipe with quick disconnect. I'll also decrease the length of the 4" flex hose as time goes on to reduce any bends.


----------

