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 Getting
Tough on Dust
Dealing with Fine Dust
Filtering the Air in Your
Shop
A dust collection system alone is not usually sufficient
protection against fine wood dust. In reality, even the best
dust collection system can leave dangerous levels of minute
airborne dust particles floating through the air, and
some can actually increase the levels of fine dust.
On this page, we'll look at the
dangers of letting fine dust run wild, and strategies
for limiting the amount of fine dust in your shop. On the
next page will round off the discussion with an overview of
the final component of an effective dust collection regimen:
personal respiratory protection.
Dust Particle Size and and
Respiratory Health
Dust particles are measured in microns, or
thousandths of a millimeter. Larger dust particles - over
100 microns or so - are heavy enough to fall to the floor
quickly. They're part of the mass of debris that collects
with such alarming speed on the floor under and around your
woodworking tools. Fine dust particles, on the other
hand, don't have enough mass to be pulled quickly to the
floor and can float through the air in your shop for a
surprising length of time. Once a 5 micron wood dust
particle is stirred up, for example, it will stay aloft for
30 minutes or longer depending on the air movement it
encounters.
Dust particles under 10 microns
constitute the primary respiratory health risk to
woodworkers. They're easily stirred up, stay aloft for
a long time, and worse, penetrate easily into the deepest
reaches of the lungs, where they are reported to cause
problems ranging from mild allergic reactions to severe and
chronic respiratory ailments. While the seriousness of the
health effects of long-term small particle fine wood dust
exposure remains under debate, more and more woodworkers,
convinced by the evidence of serious health risks that
currently exists, are beginning to take fine wood dust
exposure seriously.
Fine dust filters like this
Shaker Felt Filter Bag fit most dust
collectors and can dramatically improve their fine
dust performance.
Improving the Filter
Performance of Your Dust Collector
Dust collectors commonly used in small shop dust
collection systems are sometimes called "chip collectors."
That's because they are really designed to do their best
work at collecting chips, shavings and large dust particles.
Many dust collectors are equipped with a filter designed to
stop only large particles and let the fine particles
associated with respiratory health problems pass through.
Because dust collectors move substantial quantities of dust
laden air, a dust collector that lets minute dust particles
pass through its filter becomes, in effect, a "dust pump,"
filling the air around it with clouds of fine dust.
There are a couple of ways to
prevent your dust collector from working against you in your
war on fine dust exposure. The simplest - and one of
the most effective - is to locate the dust collector
outside, or in a room that's separate from your shop and has
its own ventilation system. For climates and shop layouts
that make this solution impossible, the best alternative is
to outfit the dust collector with a filter that traps fine
dust particles.
For most dust collectors, a Shaker
felt filter bag offers a simple, affordable filter upgrade.
Shaker felt is a fabric specially designed to trap small
dust particles (down to one micron) without seriously
impeding the air flow of the dust collection system.
Of course, the best way to solve the "dust pump" problem is
to buy a dust collector equipped with a fine particle filter
in the first place.
Some dust collectors are offered
with the same basic style of filtration bag that is common
to "chip collectors", but with a much finer filtration
capacity. The
Delta 50-760, for example, comes with a filter bag that
traps particles down to 1 micron. Other dust collectors are
available with a "canister" filter that consists of a
pleated fabric filter encased in a mesh container that fits
on top of the dust collector. Jet dust collectors, including
the
DC-650, the
DC-1100 and the
DC-1200 all are available with canister filters that
filter dust particles down to 2 microns. An added advantage
of canister filters is that the pleated filter
material greatly increases the surface area of the
filter, which means that the filter won't clog with
dust nearly as quickly as a bag and inhibit air flow through
the dust collector.
Shop Air Filtration
Systems
Even if you've done everything you can to
improve your dust collection system's filtration
performance, don't be surprised to still find a tell-tale
coating of fine dust settling on the surfaces in your shop.
The fact of the matter is, much of the dust created in a
wood shop never gets a chance to end up in your dust
collector. In spite of your best efforts to set up an
efficient, powerful dust collection system, some amount of
the fine dust created by the tools it services will always
escape into the air in your shop. Dust created buy hand-held
sanders, for example, is among the finest to ever enter your
shop, and is also extremely difficult to successfully
capture in your central dust collection system.
Over time, the fine dust problem
multiplies. The fine dust particles missed by your dust
collection system remain in your shop, ready to be stirred
into a dust cloud by the slightest movement of air, and you
add to the problem every time you turn on one of your
power tools. Until you develop a system for dealing with the
majority of the fine dust that your dust collector misses,
you really don't have fine dust under control. Air
filtration systems are designed to complement your dust
collection system in ridding your shop of the majority of
fine dust particles.
Choosing an Air Filtration
System
Like dust collectors, the performance of an air
filtration system is measured by the volume of air the unit
will move in cubic feet per minute (cfm). To be effective,
an air filtration device should be rated to move the entire
volume of air in your shop 6 to 8 times per hour. The Jet
AFS-1100B Air Filtration System has a maximum cfm setting of
1044, which means that it will filter entire volume of air
in a 20' X 20' foot shop more than 12 times per hour. The
unit has a built-in timer with settings for 2, 4 and 8
hours, making it a very convenient system to use - just flip
the switch when you walk into your shop and forget about it.
If you've already set up a central
dust collection system, you'll be glad to hear that the Jet
air filtration system is easy to install. Just use the 4
eyebolts that come with the unit to hang it from the ceiling
of your shop in a central location where it will be able to
set a circular current of air in motion.
Portable Fine Dust
Collectors
Air filtration systems do a fine job of keeping the
accumulation of fine dust in your shop to a minimum by
continuously filtering the entire volume of air in your
shop. At times, though, its beneficial to have a little "on
the spot" fine dust control. In most shops, a random orbit
sander and a palm sander are indispensable equipment, but
any one who has ever used either tool knows they are just
about as good as producing clouds of ultra fine dust as they
are at smoothing wood surfaces.
A
lightweight,
portable dust collector is the perfect companion for an
air filtration system. These compact units are easy to move
around your shop, and give you excellent control of the,
hard-to-capture fine dust produced by handheld sanders,
power carving and grinding tools, hand-held routers and
trimmers, and many other tools that don't lend themselves to
being connected directly to a dust collection system.
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