Labconco Intelli-Sense Multi-Speed Blowers 7183413 - Manuel (Page 38)

Chapter 7: Modifying Your Blower
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Original instructions
chemical fumes. You will be handling low to moderately corrosive materials, so
you have selected a Coated Steel Blower.
The information following for the 90° elbow tells you that each 90°, 12" diameter
elbow has the equivalent resistance of 25 feet of straight duct. The zero pressure
weathercap has 5 feet of equivalent resistance. The total equivalent feet for the
system is:
Feet of straight duct 30 Feet
2 elbows @ 25 feet each 50 Feet
1 zero pressure weathercap @ 5 feet 5 Feet
85 Feet
The chart following converts “equivalent resistance in feet of straight duct” to
static pressure. So the static pressure of 85 equivalent feet of 12" nominal duct is
equal to (85/10) x 0.011" = 0.094". Now this is added to the hood static pressure
of 0.22" for a total system static pressure of 0.314". Look at the performance data
in Chapter 4 for Coated Steel Blowers. Refer to the 0.25" to .50" range at 725
CFM since this is closest to 0.314". The chart will lead you to select a Coated
Steel Blower model that is 10" set at 900 RPM or a 12" set at 600 RPM. In this
example, models 7061110, 7061112, 7061120 and 7061122 all would work. A
manual damper would also provide additional fine tuning of the blower/hood
exhaust system.
Sizes and Pressure Losses in Thermoplastic Duct
This chart provides static pressure losses for 10' long duct lengths of various
diameters over a range of airflows in CFM for use in sizing hood/blower
combinations at 100 feet per minute.
Nominal Diameter/Inches 6 8 10 12 16
Actual OD/inches 6.625 8.625 10.750 12.750 16.000
Actual ID/inches 6.25 8.250 10.375 12.375 15.625
Catalog Number 47086 47189 70272 56020 56050
Shipping Wt./lbs. 20 35 50 65 80
Airflow/CFM
Static Pressure Loss/Inches H
2
0
For Each 10 ft. of Duct Length
250 .039 .011 .003 .001 --
500 .147 .037 .013 .005 .001
750 .321 .079 .026 .011 .003
1000 .557 .140 .043 .018 .005
1250 .855 .210 .066 .027 .008
1500 -- .300 .095 .039 .012
1750 -- .380 .130 .053 .016
2000 -- .485 .155 .067 .020
2500 -- -- .245 .109 .031
3000 -- -- -- .145 .042
4000 -- -- -- .240 .074
5000 -- -- -- -- .120