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Guide to
Dust Monitors
Dust Monitors are designed to monitor the amount
of airborne particulates in the environment over a
period of time. They can be used to show OSHA
Compliance, ensure worker safety, or for research
purposes. Because exposure to dust and
particulates is hazardous to human health,
organizations such as the National Ambient Air
Quality Standards and OSHA have exposure
guidelines in place to guarantee the safety of
workers and others who may be exposed to
airborne particulates. The standards can be based
on the size or type of the particulates as shown in
the examples below:
National Ambient Air Quality Standards
Particle Matter Level Averaging Time
PM 10
PM 2.5
PM 2.5
Examples of Exposure Limits:
OSHA PEL/TWA 8 hour: 15mg/m3
OSHA Ceiling Value: 10mg/m3 (Silica)
OSHA IDLH(Immediately dangerous to life or
health): 25mg/m3 (Silica)
0.15mg/m3
0.015mg/m3
0.35mg/m3 24 hours
24 hours
Annual
Application Note
Light-Scattering Dust Monitor
Light Scattering Monitors are the most common in
the industry. Dust is introduced to the monitor via a
particle inlet which funnels the particulates toward
a laser beam. The particles pass through the
beam in single file and the instrument measures
the concentration via the amount of light that is
scattered as the particle passes through the
beam.
These monitors are simple to
operate, and can be used for longterm monitoring making this the
better choice for applications such
as calculating worker exposure in an
8-hour period or research studies
that require 24 hours of monitoring.
The disadvantage of light scattering
models is they require a K-factor (also called the
calibration factor) in order to provide an accurate
count. In order to get the K-factor, a gravimetric
analysis of the particulate(s) being measured must
be performed. This involves taking a sample of the
dust at the site and sending it to a qualified lab for
analysis to determine the mass concentration.
Once the mass concentration is known the
following formula can be used to determine the Kfactor: K = C / R, where C is the mass
concentration of the sample and R is the counts
per minute from the dust monitor.
Kanomax offers two distinct dust monitoring
solutions, model 3443 is a light-scattering dust
monitor while model 3521 is a piezobalance dust
monitor. Each type has its benefits and limitations
and understanding those is the key to deciding
which one is right for a specific application.
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It is possible to estimate the K-factor if the mass
concentration of the particulates being monitored
is known, but as each environment is unique this
method will not provide the greatest possible
accuracy. For precise measurements it's always
best to sample the particulates at the actual
measuring site at the exact location the dust
monitor will be placed when monitoring.
The light-scattering monitor is a good choice for
long-term measuring applications, such as area
monitoring, indoor air quality investigation, point
source monitoring (such as welding), and personal
exposure monitoring. The Kanomax model 3443 is
compact and lightweight, has built-in datalogging
for up to 100,000 measurements, PC USB interface,
and an analog output that can be used to control
other devices.
Piezobalance Dust Monitor
The piezobalance monitor can also measure some
particulates, such as oil mist, that cannot be
measured with a light-scattering monitor. The
drawback to this type of monitor is that the crystal
must be cleaned every hour which makes it
unsuitable for long-term measurements. It's a good
choice for applications such as milling, honing or
boring operations. The Kanomax model 3521 is
designed to be simple to operate and clean. It
requires no special training to use and comes with
an RS232 interface for downloading data to a PC.
The unit itself can store up to 500 measurements.
In contrast, a piezobalance dust monitor operates
by electrically charging the particulates it takes in.
The charged particulates are then deposited on a
piezocrystal. By measuring the change in
frequency of the crystal the monitor is able to
determine the mass concentration of the
particulates. Since the actual mass concentration
is measured there is no need for a K-factor with this
type of monitor.
Product specifications for our dust monitors and
other products can be downloaded from our
website at www.kanomax-usa.com. If you have
any questions about dust monitors, need help
selecting the right product for your application or
would like to request a quote please contact us at
info@kanomax-usa.com.
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