Fluke 975 Application Note

Fluke 975 Air Meter:
Environmental carbon
dioxide analysis
Carbon dioxide (CO
2
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 is used in plants for
2
photosynthesis (CO in, O
2
through the respiration of aerobic
organisms (O in, CO
2 2
by decaying life forms and outgassing
volcanoes, and is a product of the
complete oxidation (combustion) of
carbon based compounds. CO
commercially produced and has many
commercial and industrial uses from
beverage carbonation to "dry ice" to
fire extinguishers. How, then, is CO
significant factor in environmental Indoor
air quality?
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
) is a naturally
out), released
2
out), released
is also
2
a
2
Processes that produce CO
2
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.
Measuring air flow at a supply register.
Application Note
CO standards
in a
2
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
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 levels will gen-
2
erally be, depending on space
usage, about 350-1,000 ppm
above outside air CO
This is well below the OSHA
workplace threshold of 5,000
ppm CO . NIOSH and ACGIH fur-
2
ther stipulate a maximum expo-
sure rate of 30,000 ppm CO
15 minutes. CO is an asphyxi-
2
ant, and at 50,000 ppm CO
considered to be an immediate
threat to life.
levels
2
levels.
2
for
2
is
2