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Designing Your Dust System (continued...)
There are several ways to determine the diameter of the branches.
  1. Determine Diameter and CFM of each Branch

  1. If the machine has a factory installed collar, the manufacturer has determined that the machine needs the size branch under normal circumstances.
  2. If the machine has a metric diameter outlet, convet it into inches, and round off to the nearest inch. When writing up your parts list you may need to order a customer reducer.
  3. If the outlet is rectangular you need to determine the equivalent round diameter. When you write up your list use a transition.
  4. If the branch is smaller than 3" diameter plan using a reducer near the machine to increase the branch ot 3". Figure the CFM for 3" (195 CFM).

  1. DETERMINE DIAMETER OF MAIN DUCT
  1. Determine which machines are your primary machines. A primary machine is the machine(s) that will operate at the same time under the worst conditions. (If you normally operate two machines, but once a week need to operate a third machine at the same time, then you must size your system for all three machines.) We generally highlight the primary machines on the drawing.
  2. Sizing the Main Trunk Line. When sizing the main trunk line start with the primary machine farthest from the dust collector. Run that size duct until the next primary branchenters the main. Increase the main size at that junction to accommodate the C.F.M. total of the two primaries. You will follow this practice all the way to the collector, sizing all primary junctions to accommodate total C.F.M. of all primaries at that point. Do not increase main duct size when a branch other than a primary enters. Your total C.F.M. requirement is the total of all primary branches. When not using a primary machine you will close blastgate and divert suction to a secondary machine.
Example: You have 3 primary machines. You have already assigned the branch diameter and CFM requirements.

Table Saw, Lathe 4" Diameter 350 CFM

Radial Saw 5" Diameter 550 CFM

A 4" branch will be run from the Table Saw until it joins with the 4" branch from the Lathe. At this point your main starts and you need to increase the pipe to handle the combined CFM (350+350 = 700). Using the CFM Chart 1 look up 700 CFM under the appropriate velocity (3500 FPM in the main for wood dust), then look at the corresponding diameter (6"). Run 6" pipe in the main from the Lathe until the branch of the Radial Saw joins the main.

Here again you need to increase your main to handle the total CFM (700+550=1250 CFM). Using the chart again you will see that 1250 CFM is slightly more than volume for 8" diameter. Drop back to 8" diameter so as not to go below transport velocity. Run the 8" duct in your main from the Radial Saw to your Dust Collector.
continued on page 12...
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CONTENTS

Access Doors30 Angle Rings19 Ball Joints34 Bellmouths34 Blastgates32 Couplings18 Design Information10-13 Duct Silencers33 Easy Connect System18 Elbows22 End Caps / End Plugs18 Extension Arms39 Flexhose40-47 Floorsweeps34 Hangers20-21 Installation Information14 Nozzles35 Offsets27 Radial Saw Hoods34 Reducers31 Spiral Pipe16-17 Stainless Pipe37 Tees27-29 Y Branches29 Transitions35 Up-Blast Stack Caps36
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Dust Collection | Ventilation Systems | Dust Control | HVAC Systems & HVAC Ducts | Ducting | Ductwork | Custom Manifold
Industrial Ventilation | HVAC System Ducting | Spray Booth Fume Control