Fluke 975 Application Note

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Brand: Fluke

Category: Accessory

Type: Application note

Model: Fluke 975 , Fluke 975V

Pages: 3 (0.63 Mb)

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Application Note
Fluke 975 Air Meter:
Environmental carbon
dioxide analysis
F r o m t h e F l u k e D i g i t a l L i b r a r y @ w w w . f l u k e . c o m / l i b r a r y
Carbon dioxide (CO
2
) is a naturally
occurring, colorless, odorless, non-
combustible gas that is ever present
in the atmosphere, usually ranging in
concentrations from 300-600 ppm
(parts per million).
In nature, CO
2
is used in plants for
photosynthesis (CO
2
in, O
2
out), released
through the respiration of aerobic
organisms (O
2
in, CO
2
out), released
by decaying life forms and outgassing
volcanoes, and is a product of the
complete oxidation (combustion) of
carbon based compounds. CO
2
is also
commercially produced and has many
commercial and industrial uses from
beverage carbonation to “dry ice” to
fire extinguishers. How, then, is CO
2
a
significant factor in environmental Indoor
air quality?
Processes that produce CO
2
in a
typical occupied space include
human and animal respiration,
decaying plant and animal life,
such as garbage in a kitchen,
and combustion processes of
fossil fuel burning equipment.
Most fossil fuel burning equip-
ment, such as furnaces, boilers,
water heaters and fireplaces, has
provisions to vent the combus-
tion products directly to the out-
doors—but venting systems can
become inhibited or even fail.
Stoves, ovens and space heat-
ers may not utilize a vent sys-
tem, relying instead on exhaust
hoods, building ventilation, or
in the case of many residential
applications, natural ventilation
through stack effect and struc-
tural leakage.
CO
2
standards
ANSI/ASHRAE Standard 62.1-
2004 Ventilation for Acceptable
Indoor Air Quality addresses
minimum requirements for ven-
tilation and indoor air quality for
typical indoor breathing spaces
that will be acceptable to occu-
pants. The requirements are
“intended to minimize the poten-
tial for adverse health effects.”
The standard is applicable to
indoor occupied spaces except
when other usages or standards
require greater amounts of ven-
tilation. Generally speaking,
ventilation rates are selected for
contaminant and odor control
based on the maximum expected
occupant density and activity
level.
When these ventilation rates
are maintained, CO
2
levels
created by human respiration
should always be at accept-
able, healthy levels.
When the occupied space is at
maximum expected occupancy
with the recommended venti-
lation rate, CO
2
levels will gen-
erally be, depending on space
usage, about 350-1,000 ppm
above outside air CO
2
levels.
This is well below the OSHA
workplace threshold of 5,000
ppm CO
2
. NIOSH and ACGIH fur-
ther stipulate a maximum expo-
sure rate of 30,000 ppm CO
2
for
15 minutes. CO
2
is an asphyxi-
ant, and at 50,000 ppm CO
2
is
considered to be an immediate
threat to life.
Measuring air flow at a supply register.