Figure Dust-Collection Needs
Static Pressure Loss
Determine the static pressure loss in the system's ductwork
The final step in setting up your system is to calculate static pressure loss (SP loss). This figure represents the friction between the duct wall and air moving in the ductwork, friction that the blower must overcome to make air move through the system.
Figure each branch separately. Start by measuring the length of the branch duct in feet. Count the number of 90° and 45° bends in it. Where a branch enters the main duct through a 45° wye, count the wye as a 45° bend for the branch.
Then, prepare a Duct SP Loss worksheet like the one found here for each branch. Find values for the equivalent length of bends in Table 3.
Now, taking each branch duct separately, figure the static pressure loss for the portion of the main duct that runs from the point where that branch enters it to the dust collector, using the Worksheet 2 format.
Add this figure to the branch duct's SP loss to find the total SP loss from the tool to the dust collector, as in Worksheet 3.
The largest value you calculate for your system then represents the static pressure loss your dust collector must be able to overcome. Enter this figure on Worksheet 1.
Worksheet 1 now shows the maximum CFM flow and static pressure loss for your system. To power your system, you'll need a dust collector that meets or exceeds both figures.
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