Grizzly G0671 - Manual (Page 32)

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Model G0671/G0672/G0673 (Mfg. Since 1/13
Determining Main Line Duct Size
the general rule of thumb for a main line duct is
that the velocity of the airflow must not fall below
3500 FpM.
use the inlet size of the dust collector as a starting
point for the main line. neck the main line down
1" for every 10' of length. this will usually keep
the air velocity above 3500 FpM and, depending
on your system, will allow you to keep multiple
branches open at one time.
For the Model g0671/g0672/g0673 this is 10".
Mark your drawing, as in
figure 29.
figure 29. Main line size labeled on sketch.
395
395
614
790 395
220
98
9“ 10“
Determining branch Line Duct Size
the general rule of thumb for a branch line duct is
that the velocity of the airflow must not fall below
4000 FpM.
For small/medium sized shops, using the dust
port size from the machine as the branch line duct
size will achieve the correct velocity in most appli-
cations. however, if the dust port on the machine
is smaller than 4", make the branch line 4" and
reduce the line right before the dust port.
Note: Systems with powerful dust collectors work
better if multiple blast gates are left open. This
also allows you to run two machines at once.
Experiment with different combinations of blast
gates open/closed to find the best results for your
system.
Write your determined branch line sizes on your
drawing, as shown in
figure 30.
figure 30. Branch line sizes labeled on sketch.
395
395
614
790 395
220
98
9“ 10“
6“ 4“ 4“
4“
4“ 4“ 5“
Multiple Dust Ports
if your machine has multiple dust ports, add the
total CFM given for each dust port size from
figure 26. refer to figure 31 and find the CFM
that is closest to your total to determine the cor-
rect branch size. split the branch line just before
the dust ports with matching duct sizes.
Two Machines on Same branch Line
if both machines will be running at the same time,
add the total CFM given for each dust port size
from
figure 26.
if both the machines will never be run at the same
time, reference the machine with biggest dust
port to
figure 31 and add blast gates after the
y-branch to open/close the line to each machine.
Total CfM branch Line Size
<500 4"
600 5"
700 5"
800 6"
1000 6"
1200 7"
1400 8"
1600 8"
figure 31. Branch line sizing chart by total CFM
(for use when multiple machines share line).