Explosions are unlikely in either the cyclone or the tube filters if
these components are sized appropriately for the system. Separation of
dust and air in a cyclone occurs rapidly, and the air-to-dust ratio is not
high enough to allow for an explosion or fire. Because of the high
pre-separation in the cyclone, little dust gets to the tube filters, and
even if there were enough dust, the filters cannot contain an explo-
sion. Static sparks are generally not a factor because the blower motor
is statically grounded. The cyclone would also be grounded if it’s con-
nected to the blower by metal ducting. Any plastic ducting should be
grounded by running a bare copper wire inside the duct.
Blowers with aluminum fan wheels are recommended for wood-
shops because aluminum is a non-ferrous material, which cannot
transmit sparks. Nevertheless, a fire could occur if the wood-dust
material is not removed and a high concentration of dust builds up in
the bags. Then a static spark from improperly grounded plastic pipe or
some other source could ignite the dust.
—PETERFEDRIGON,Cleveland, N.Y.,
from a question by Gary Gilbert, Somerville, Mass.
Sizing a Dust-Collection System
R
ECENTLYI CONSULTED WITHa woodworker who was adding a
dust-collection system to his shop. He wanted to run 26 ft. of
21 ⁄ 2 -in.-dia. tubing to collect the dust and wondered how powerful a
collector he would need. I told him that, first of all, his plan of run-
ning 26 ft. of 2^1 ⁄ 2 -in. tubing would not work. He would need to use an
extremely high-powered blower (the fan of the central collector) to
move the volume of air required to convey the dust generated by a
tablesaw, jointer, planer, or shaper. Though it’s beyond the scope of this
CHAPTER ONE