pre-separator location

[Rick T]

In most cases I've seen documented where the separator is used as a "pre-separator", it's located upstream but pretty much beside the impeller. Has there been any work done to determine how moving the pre-separator further upstream affects performance?
Occasionally, locating it nearer the dust source might be possible, in fact desirable, or perhaps some might choose to locate the DC equipment in a separate adjoining room, closet or perhaps high on a wall but want the collection pail to be conveniently located for frequent emptying etc, or just because of space considerations.
I expect the pre-separator does impose a certain amount of loss, but on the other hand, the clean air will be somewhat more easily propelled than dust-laden air. 

[phil (admin)]

I have often suggested:

(1) Placing a pre-separator near jointers/planers (the big chip producers).  The pre-separator should only serve those devices.  For other devices (table saw, band saw, etc.), the pre-separator isn't in the "circuit."

(2) Adding a baffle to the ring of the DC.

Kind of the best of both worlds.  The pre-separator is easy to empty, and sitting right next to the jointer/planer, can be monitored to prevent over-filling.

And when you want to use the tools that produce the finest dust, the pre-separator (and its hit to CFM) isn't part of the equation, so you maintain maximum airflow.

[Rick T]

I have often suggested:

(1) Placing a pre-separator near jointers/planers (the big chip producers).  The pre-separator should only serve those devices.  For other devices (table saw, band saw, etc.), the pre-separator isn't in the "circuit."

(2) Adding a baffle to the ring of the DC.

Kind of the best of both worlds.  The pre-separator is easy to empty, and sitting right next to the jointer/planer, can be monitored to prevent over-filling.

And when you want to use the tools that produce the finest dust, the pre-separator (and its hit to CFM) isn't part of the equation, so you maintain maximum airflow.

There's been so much discussion here focusing on the separation device itself that not too much attention is paid to the design of the network overall.
The answer you've provided isn't exactly  the situation I was thinking about, but does play into it now that you mention it.
Thinking about a simple case where a pre-separator is planned to be located with a DC, but the best location for convenience sake is for the pre-separator to be 10' upstream from the DC'is impeller, and on the single trunk line that serves all the shop equipment, and said equipment can be isolated by blast gates from the other equipment. I was wondering if there is a practical difference in the pre-separator's efficiency/effectiveness being say 10' away from the impeller vs being immediately beside (upstream of) the impeller as is most often the case in most examples discussed. So basically the question is how does distance upstream effect the pre-separators operation and the overall operation of the DC network?

[retired2]

I was wondering if there is a practical difference in the pre-separator's efficiency/effectiveness being say 10' away from the impeller vs being immediately beside (upstream of) the impeller as is most often the case in most examples discussed. So basically the question is how does distance upstream effect the pre-separators operation and the overall operation of the DC network?

Rick,

There should be no "practical" difference in air flow whether the separator is 1' or 10' from the fan IF both locations use exactly the same feet of pipe, exactly the same number of elbows, and exactly the same amount of flex hose.  My bet is when you move it further away you are going to start adding plumbing to get it reconnected.  If you add to the plumbing there will be losses, if only small ones.

Retired2

[Rick T]

I was wondering if there is a practical difference in the pre-separator's efficiency/effectiveness being say 10' away from the impeller vs being immediately beside (upstream of) the impeller as is most often the case in most examples discussed. So basically the question is how does distance upstream effect the pre-separators operation and the overall operation of the DC network?

Rick,

There should be no "practical" difference in air flow whether the separator is 1' or 10' from the fan IF both locations use exactly the same feet of pipe, exactly the same number of elbows, and exactly the same amount of flex hose.  My bet is when you move it further away you are going to start adding plumbing to get it reconnected.  If you add to the plumbing there will be losses, if only small ones.

Retired2

This is one of those times when it would be nice to have the lab and equipment to measure the actual effect of changes such as this., and even the effect of using flex pipe vs solid when there is a viable alternative to choose either, or limited amounts one or the other. Thx for the opinions and advice.