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Appendix D
Frequently Asked Questions (FAQs)
EVM Series User Manual
Appendix D
Frequently Asked Questions (FAQs)
Particulate Measurements
Question
Response/Solution
1.
What do the impactor cut-
points represent?
Depending on the environment and the industrial processes (such as sanding,
cutting, crushing, grinding, and transportation), the type and size of the
particulates will impact the human body in different areas, affecting the nasal,
throat, and/or lung area.
The impactor cut-points represent the particle size you will be sampling.
Inhalable dust is 100 microns and smaller. This dust is usually filtered through
the hairs and membranes in your sinuses. 10 microns and smaller is thoracic,
and dust in the 4 to 10 micron size can get caught in you windpipe and other
regions. 4 microns and smaller is respirable and this is what causes concerns
and the need for PM4.
2.
How does the impactor
function when there is a
build-up of particulates (in
a conical shaped
pyramid)?
When the build-up of particulates form a shaped pyramid, it will not measure
appropriately. This is the indicator to clean the impactor.
The reason:
As with any impactor-type filter, this filter relies on the larger
particles being unable to “turn the corner”, striking the greased-plate and being
filtered out of the stream. As the pyramid builds up more and more, particles
will begin to gently slide on past the impactor plate. We provide a fourth inlet
which can be connected to a cyclone if extreme environments and/or longer
run-times are needed.
NOTE: the impactors are designed to work correctly
ONLY at 1.67 L/min.
3.
Is it possible to do an
inhalable or respirable
gravimetric sample?
Yes, it is possible to do inhalable and respirable gravimetric sampling. This can
be accomplished through the "dial-in" impactors or with a cyclone in the open
(4th) hole on the turret. This hole is used for zeroing the instrument as well as
allowing the use of a cyclone in that inlet port.
4.
How do I set the cut-points
for particulate
measurements?
Turn the turret until the appropriate setting is displayed on the instrument’s
screen. (Settings include: PM2.5, PM4, PM10, and PM.
NOTE
: PM is
unfiltered particulate collector and allows all sizes through the dust path for
collection and measurement.)
5.
How often do you need to
apply the grease to the
impactors?
The impactors require periodic cleaning (and greasing) which is dependent on
the density of air particulates floating in the intended environment. A relatively
dusty environment (approximately under 10mg/m
3
) should last an entire day.
When dust pyramids form on impactor plates this signifies they require
cleaning and greasing. Rrefer to Impactor Care Section and the Optical Engine
Maintenance and Cleaning Section in
APPENDIX
D
