Full Product Manual

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Model W1666/W1685 (For Machines Mfd. Since 2/15)
SETUP
Calculating Duct Resistance
Adding duct work, elbows, branches and any other
components to a duct line increases airflow resistance
(static pressure loss). This resistance can be minimized by
using rigid (smooth) pipe and gradual curves, as opposed
to flexible pipe and 90˚ elbows.
To help you think about this resistance, imagine riding a
bicycle in a tunnel that is an exact replica of your duct
work. If the inside of the tunnel is very bumpy (flexible
pipe) and has a lot of sharp turns (90˚ elbows), it will take
a lot more effort to travel from one end to the other.
The purpose of calculating the resistance is to determine
if it is low enough from the machine to the dust collector
to meet the given CFM requirement for the machine. Use
the following tables to calculate the resistance of duct
work.
Duct Dia. Approximate Static
Pressure Loss Per
Foot of Rigid Pipe
Approximate Static
Pressure Loss Per
Foot of Flex Pipe
Main
Lines at
3500 FPM
Branch
Lines
at 4000
FPM
Main
Lines at
3500 FPM
Branch
Lines
at 4000
FPM
2" 0.091 0.12 2 0.35 0.453
2.5" 0.08 0.10 7 0.306 0.397
3" 0.071 0.094 0.271 0.352
4" 0.057 0.075 0.215 0.28
5" 0.046 0.059 0.17 2 0.225
6" 0.037 0.047 0.136 0.18
7" 0.029 0.036 0.10 6 0.141
8" 0.023 0.027 0.08 0.10 8
9" 0.017 0.019 0.057 0.079
Fitting
Dia.
90˚
Elbow
45˚
Elbow
45˚
Wye(Y)
90˚
Wye(Y)
3" 0.47 0.235 0.282 0.18 8
4" 0.45 0.225 0.375 0.225
5" 0.531 0.266 0.354 0.236
6" 0.564 0.282 0.329 0.235
7" 0.468 0.234 0.324 0.216
8" 0.405 0.203 0.297 0.18 9