Determining Main Line Duct Size; Multiple Dust Ports; Two Machines On Same Branch Line; Determining Branch Line Duct Size - Grizzly G0671 Owner's Manual

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 33.
9"
figure 33. Main line size labeled on sketch.

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 34.
-30-
10"
4"
9"
4"
4" 4"
figure 34. Branch line sizes labeled on sketch.

Multiple Dust ports

if your machine has multiple dust ports, add the
total CFM given for each dust port size from
figure 30. refer to figure 35 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 30.
if both the machines will never be run at the same
time, reference the machine with biggest dust
port to figure 35 and add blast gates after the
y-branch to open/close the line to each machine.
Total CfM
<500
600
700
800
1000
1200
1400
1600
figure 35. Branch line sizing chart by total CFM
(for use when multiple machines share line).
g0671/g0672/g0673 dust Collector
4" 6"
10"
5"
branch Line Size
4"
5"
5"
6"
6"
7"
8"
8"