Assistance with Ductwork Layout for Your Shop.
Plus $50.00 Off*!
Why Use Metal Ductwork?
Metal pipe is smoother inside than
corrugated metal or flexible hose. It is much more efficient at
the wye, elbow, and branch fittings. Smooth transitions result in
less air turbulence, friction, and static pressure loss. Metal pipe
is less expensive than PVC in diameters over 4" and has a much
larger variety of adapters available. Metal ductwork is robust and
rigidit will withstand any level of stress and high vacuum.
Choose either premium
ductwork or the economy
Planning Your Dust Collection
Planning your duct layout on paper is the first step. First, draw
the locations of your woodworking machines, doors, windows, cabinets
and other fixtures that may obstruct your ductwork. Certain machines
should be located closer to your dust collectors. Figures 1 and
2 show two alternatives for laying out ductwork in a typical shop.
Any one of these runs may best suit your shop depending on the placement
of your collector, machines and obstructions.
The Diagonal Run,
locates your dust collector in the corner of your shop, away from
high activity, usually in dead space. This generally results in
the use of less ductwork.
The Central Run,
locates the collector centrally on a wall with a short run of main
pipe running down the center of the shop. The advantage is that
your dust collector will generally be located closer to all of your
machines and may require less overall length of pipe. It allows
you to run your pipe along your joists.
The Perimeter Run
(not shown), requires a long main run around the walls of
the shop. The advantage of this plan is that it is the best design
for avoiding obstructions at the ceiling level that would eliminate
one of the other plans. Drops from your main to machines will tend
to be out of the way. With this design the pipe can be run at ceiling,
wall or even floor level. The drawback of this plan is that it requires
more main ductwork and fittings as well as it creates more static
Dust collector location:
Variables that play a role in where to place the dust collector
include: Noise level of the collector, footprint and height, the
overall length of your duct, obstructions at the ceiling and wall
levels, level (e.g. heating and plumbing obstructions), direction
of joists (for running pipe), electrical service, locations of doors
Keep the length of runs to a minimum: Your system will perform best
with shorter runs. It will be less expensive to equip, and easier
to build and maintain.
of woodworking machines:
Certain machines require more CFM and should be placed closest to
your dust collector providing better airflow and chip collection
(Chart 1). Place your least demanding machines at
the end of a run. A floor sweep [#N-FSW] should be
used near machines where dust collection is inefficient or impractical.
Design Elements of Your Dust
your main run off the dust collector (Figure 3) a
90º elbow (the same diameter as the opening)
connects to the intake port of your dust collector (Chart
2). Use a draw band connector (#N-DBC) for most flexibility.
Youll need to determine the distance from the end of the elbow
to the ceiling. Use another elbow to connect the vertical pipe to
the main on the ceiling.
diameter of your main duct normally will be determined by
the diameter of the intake port of your dust collection system (Chart
2). (Remove any wye adapters before measuring this opening,
cyclone units typically will not have this adapter). Avoid runs
of ducting (and machine ports) smaller than 4" diameter. Spiral
ductwork requires couplers to connect pipe sections and fittings
of 45º laterals and wyes [#LAT] or [#WYE]
Branches off your main
run may be a smaller diameter (4" is typical for a small shop).
Use laterals and wyes as transitions from main to branches and to
reduce to the smaller diameter of the branch. To determine the placement
of a wye on the main duct branch, draw a line from the machine to
the main duct meeting it at 45º. The intersection will determine
the placement of the wye (Figure 1). In the case of
an obstruction, use a combination of 45º elbows [#45E].
A length of flexible metal pipe [#N-FH] can be used
to circumvent the obstruction.
Drops to your machines
are shown in Figure 3. If your machine has a 4"
port, a length of 4" flex hose (#N-CVD or #N-J13)
will run from the port to a blast gate. In Figure 3, the gate connects
to the main via a lateral, 45º elbow and a length of 4" pipe.
At the drop at the end of a run, a 90º elbow off the branch is used.
Connect your pipe to the ceiling or wall: Use ceiling brackets (#N-
HB), for a ceiling and wall suspension use brackets every
six feet of main pipe. Brackets and hangers should be at least four
inches from any pipe couplers or other joints. Once your drawing
is complete, indicate what components are needed and make a list
of components (bill of materials).
For safety, always use work gloves and goggles when assembling your
system. The main duct may be assembled on the ground in sections.
If you work on top of scrap plywood you can layout the position
of angled branches, to determine the length of straight pipes that
extend between them. If you have to cut a piece of pipe, use a saber
saw and a metal cutting blade. Wrap tape around the pipe at the
position of the cut, drill a pilot hole and cut using the edge of
the tape as a guide. Apply caulk at the connections and force fit
the components together. Secure with pop rivets.
Note: Sheet metal screws may snag wood chips and cause obstructions.
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