Application Note

3 Fluke Corporation Growing your business through indoor air quality particulate profiling
While slightly higher than out-
side values, this is a fairly typical
particle level. However, in one
location, the particulates were:
You’ll notice that particle sizes
in almost all areas increased.
Quite often, larger particles are
providing nutrients to the smaller,
biological particles, as well as
transporting them. That’s how fil-
ters that remove mostly larger
particles also wind up removing
many viruses and bacteria from a
system.
The higher counts indicate a
problem that needs to be investi-
gated. Determine specifically
where the high counts occur and
then start asking questions. Is
there an excessive source of
moisture from an improperly
draining pan under an evaporator
coil? What kind of ventilation
does the building have and how
old is it? Has there been any new
interior construction, carpeting, or
painting?
By addressing all aspects of
the situation, you’ll treat the real
problem, not just the symptom,
and give your customer specific
data to base buying decisions on.
Step 3: Making the measurements
Once you’ve collected data,
transfer the information to a
computer and convert it into a
spreadsheet. Compare the counts
in each area against the baseline
and between each other. You
should see patterns develop.
When you detect a high-volume
area, see if it’s just one particle
size or several, and think about
what kinds of contaminants could
be involved. Then, compare the
particle counts to air flow balanc-
ing in the building
. Always
remember to take readings of the
outside air in order to make
meaningful comparisons with the
particle levels indoors.
If you think the system itself
is transporting contaminants,
consider whether to propose
re-balancing the existing system
or adding a mechanical solution
such as dehumidifiers or a better
filter. Sometimes the solution can
even be as simple as blocking off
a room or identifying problematic
behavior.
Here’s one example of a par-
ticulate profile in a commercial
office. The baseline six particle
size scales showed:
To conduct an IAQ inspection, get
a map of the HVAC system, as
installed, and use that to create
an inspection route. Plan to take
temperature, humidity, and parti-
cle samples in every zone of the
building, especially in any areas
where there have been com-
plaints, as well as outside the
building, as a baseline. Within
each zone, take a measurement in
the middle of the space as well as
near the air intakes, outtakes, and
any other HVAC system elements.
Make particular note to measure
both upstream and downstream at
any HEPA filters.
Also use your own senses—
look for signs of moisture leaks,
smell the air for mold, and ask
the people who frequent each
area if they have experienced
anything different, such as smells,
headaches, or eye irritation.
Don’t be intimidated by partic-
ulate counters—newer models
designed specifically for HVAC
technicians are easy to use. For
example, to use the Fluke 983,
power up the unit, press F1, and
use the probe to start sampling. It
will simultaneously record the
relative humidity and tempera-
ture conditions and sample a
g
roup of particulate measure
-
ments in less than 25-seconds.
As you take your samples, use
the lab
eling feature on your par
-
ticle c
ounter to identif
y samples
taken from different rooms, the
particle c
ounting mode, air sam
-
pling volume and time.