An important addition to workshops and machines is a dust collection
system. Dust collection systems make shops cleaner, safer, and
extend the life of a machine. A clean shop is a safe shop.
Uncontrolled dust can cause potentially serious health risks,
contribute to messy work environment that can cause personal injury,
and be the cause of premature machine failures.
Sawdust, wood chips, and any other particles generated by cutting
the wood, particle board, plywood, etc., become hazardous if they
are inhaled. These products are created with the use of resins,
alkaloids, silica, tannins, toxic organic and inorganic elements.
Not to mention the insecticides, formaldehydes, and other toxins
that come in contact with the tree in nature. Exposure to dust
containing any of these can cause respiratory ailments, allergic
reactions, skin problems, and liver, kidney, or blood diseases. Keep
in mind, the finer dust particles can be easily inhaled and
ultimately end up within the bloodstream. These are the realities as
pertaining to proper dust collection in the modern workshop.
Designing the Proper Dust Collection
System
In order to design a cost-effective and
efficient dust collection system, the ducting must be carefully
planned. The simpler the system, the cheaper and more efficient it
will be. Before getting started, there are many variables which
should be considered, such as: type of dust collector, type of
ducting material, location, layout, and the budget for your system.
Dust Collectors
There are basically two types of dust
collectors: single- stage, and two-stage. A single-stage unit is an
inherently cheaper system which consists of an inline impeller which
passes debris through the impeller and deposits the dust and debris
into a filter bag. As dust and debris collects in the bag or drum,
the system becomes increasingly less efficient. Precautions need to
be taken with single-stage systems to prevent large objects, or any
objects that can cause sparks when passing through the impeller.
Objects that are too large can cause damage to the impeller, thus
resulting in impaired performance. Objects that cause sparking
exponentially increase the chance of a fire or dust explosion. A
good dust separator should be installed so that it will trap metal
objects before they reach the impeller. If you suspect a spark was
generated, the unit should be shut down immediately and the bag
emptied into a safe airtight container. Two-stage units draw
dust and debris into the system, but deposit the majority of the
debris in the first stage collection container before entering the
impeller. At this point, only fine dust passes through the impeller.
As this fine dust passes through the impeller, the second stage
consists of a fine micron filter element which filters the fine dust
as the air is exhausted from the dust collector back into the shop..
Choosing Piping
There are two types of piping to choose
from: metal or plastic. There are several different types of metal
ducting such as stove, heat, and ventilation piping, as well as
piping designed specifically for dust collection systems. Metal
piping is generally more expensive, but has many advantages over
plastic piping. One advantage of using metal piping is the fact that
it is a conductor and does not contribute to static electrical
charge build-up. Although suspended dust within the ducting still
generates a static electrical charge, metal piping is a conductor
that can be easily grounded, dissipating the charge. If metal piping
is to be used for the system, it should be of 26 gauge material or
heavier so that the ducting will not collapse from the vacuum. The
ideal ducting is piping that is specifically designed for dust
collection purposes because it is the most efficient; however, this
is the most expensive. The use of metal piping does make
installation more difficult, and may not be airtight if it is not
specifically designed for dust collection. All leaks should be
sealed for optimum performance.
Plastic piping, such as PVC or ABS, is the least expensive, readily
available and easily assembled, but it has many inherent problems.
Plastic piping is an insulator; thus static electricity is generated
as dust particles travel through the ducting. It is very important
to ground a plastic ducting system in order to dissipate the static
electrical charge. This can be accomplished by running bare 16 AWG
copper grounding wire, which should be stranded, braided and run
inside the entire ducting system (braided antenna wire works well
too). At any joints, the wire should be soldered so that there is a
smooth transition at the joint. This smooth transition will help
prevent debris from getting trapped, thus clogging the system. In
addition, this braided wire should be spiral-wrapped around the
exterior and grounded as well. Both metal and plastic piping require
final connection to the machines. This connection should be made
with flexible hose, not rigid piping. The use of flex hose will
allow movement of the machine without damaging the ducting system.
Metal piping typically connects easily to flex hose whereas plastic
usually does not always mate correctly. A common method for this
connection is to wrap duct tape around the plastic fitting
increasing the diameter, or fabricate a wooden donut so that the
connection can mate correctly. When using the flexible hose, try to
minimize the lengths, because its deeply corrugated surface can
increase static pressure loss by as much as 50% over smooth-walled
piping.
Location of Dust Collector
The location of the dust collector is
very important because it will affect the over all efficiency and
cost of the system. When deciding the location of the dust
collector, do not consider installing it in a room that has any
ignition source. In addition, keep in mind that if installing
outside the shop area in a small room, the air removed from the shop
must be exhausted so that there won’t be a pressure differential
causing the dust collector efficiency to drop.
Geometrics
200 Martin Lane Elk Grove Village, IL 60007
