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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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