A Pneumatic Question

I guess my question is, will the dust/chips still have to rise the seven feet in elevation, as before?

If not, then keep it low. Kinda like pumping water. Gravity works against you.

If, on the other hand the dust still has to climb those seven feet, it becomes a question of velocity in each stack.

the chips are the heaviest parts that you want to keep in suspension as they move towards your collection drum. keeping your duct runs short will help maintain suction when the system is energized. I'd place the duct expected to carry the heaviest particles as close as possible to the fan...probably a lathe or planer in your case, most saws will produce far more dust than chips. keep your runs short with gentle bends (if any)

Neither It's best to run it on a horizontal plane about the height of the input to the dust collector.

But if you have to run other then that run it down. Multiple collection tubes each are drawing a porportion of the dust collectors total cfm. If the last run is up it drawing all the cfm to move the chips.

What matters is the velocity of air flow, if it's strong enough(and it should be) then no problem....It's also a good way to tell when it's time to check the collector bag, When the chips start falling back out of the collector tube, it's time to empty the bag....

Good find!

Here's more information on my DC system. How can I improve on the air flow?

This drawing is different than the description in the original post, is it the existing or proposed system? Have you checked the link in #5? Is your chip separator cyclonic or a baffle in a box? Is there a problem with air flow now? If so, how does it manifest itself? Larger diameter pipes and higher CFM blower are the way to go.

The sketch shows the proposed layout. Most of it is installed, but I can still make changes if necessary. The separator is a 55 gal drum; no baffles or cyclone. The run from the saw to the separator is about 4' and to the blower, about 4'. From the blower to the outside is about 16'. When I bought the DC, I used it once, then took it all apart and scrapped everything, keeping only the blower and motor.

According to your drawing, it would be more efficient if the blower is lower and nearer to the separator. The outlet can remain as it is, at the same height.

I would recommend following

1) Put a cyclone to separate heacy chips for best efficiency. Else you must put baffles to ensure there is no short cut. This is must .

2) Your deisgn of velocity must have enough flow to carry the dust to the collector.

If space is not a constraint placing the plenum duct lower is better.

If using compressed air is okay with you, you can use this.

http://english.exair.com/airamplifier/SuperAirAmplifier.php

I've used them and have had good results.

regards,

Vulcan

Probably the biggest reason the dust collection system goes vertical is because of how the traffic flow is impeded by low horizontal ducting. If they can be a straight shot out of the shop without interferring with that traffic flow there would certainly be better draw.

At some point it is probably going to have to rise to get to the bin or dumpster.

The DC system is partially built. I can lower the blower to about 42" above the floor. The separator is used to catch large chips and has no baffles. Only fine dust will pass through the blower and be blown outside. There are no filters used, so my CFM and velocity should be unrestrictive. For now, only my saw is hooked up. When I run ducting to sanders, I will only be handling light dust, so it should be able to pass through the blower without any reduction in CFM or velocity. That's the way I see it. If I am wrong in my thinking, please let me know. BTW, the blower is 1-1/2 HP and the impeller is 10" diameter. I'm using 4" sch 35 PVC sewer pipe. I don't have any neighbors, so I can discharge directly to the weather. I realize I will be losing heated or air conditioned air with this method. That's OK. The DC will be running only a few minutes at the most. At present, I don't have any runs at ceiling height, but may in the future.

As a person with a farm boy back ground and on our farm we blew everything I can tell you from hands on experience that for a given blower of sufficient strength you can blow straight up 200 feet but will have clogging trying to blow 50 feet on the horizontal with the same unit. Vertical is not the issue but horizontal can be problems. I do not feel that the volume of material in a wood working shop should ever be an issue but I could be mistaken.