A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
C.F.M.: A measure of volume of air in cubic feet
CANCER: A general term used to characterize a
clinical condition in which cells continue to
grow in an uncontrolled manner.
CARBON DIOXIDE: (CO2), a clear, odorless gas.
It is found in nature, but it is also made in
diverse ways. Plants and animals make carbon dioxide
in breathing. Although it is mostly not poisonous,
carbon dioxide can cause suffocation. The level
of carbon dioxide in the blood and other tissues
affects the acid-base balance of the body.
CARBON FILTER: a type of air filter that uses
activated carbon for the removal of gaseous contaminants.
CARBON MONOXIDE: A clear, odorless, poisonous
gas made when carbon or other fuel is burned,
as in gasoline engines. Carbon monoxide will attach
to red blood cells. This prevents the blood from
moving oxygen from the lungs to the body tissues.
CARBON MONOXIDE POISONING: A poisoned state in
which carbon monoxide gas has been breathed and
soaked up by the blood. Too much carbon monoxide
limits the ability of the blood to transport oxygen.
This can result in headache, loss of sleep, trouble
breathing, and death. In a small-enclosed space,
death can occur within minutes unless emergency
treatment is given. A sign of carbon monoxide
poisoning in a patient is a cherry-pink skin color.
It is treated by removing the patient from the
source right away and giving oxygen.
CARBONIC ACID: An acid that is made when carbon
dioxide is combined with water. Also, called seltzer,
CARBOXYHEMOGLOBIN: A compound produced when carbon
monoxide links with red blood cells. It is breathed
into the lungs and enters the bloodstream. It
blocks the sites on the cells that carry oxygen.
Oxygen in the blood decreases and, when it decreases
is too much, suffocation and death result.
CARCINOGEN: A substance that can cause the growth
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CARCINOGENICITY: the relative risk or potential
of a compound causing caner in humans.
CARCINOMA: The generalized group of cancers that
develop in epithelial cells.
CARDIOVASCULAR: having to do with the heart and
circulatory system (veins and arteries)
CARRIER: A person in apparent good health who
harbors a pathogenic microorganism.
CARRIER GAS: The mixture of gases that contains
and moves the contaminant material. Components
of the carrier gas are not considered to cause
air pollution or react with the contaminant material.
CATALYST: a material that promotes the rate of
a chemical reaction but does not change the end
result from the reaction.
CEILING OUTLET: A round, square, rectangular,
or linear air diffuser located in the ceiling
which provides a horizontal distribution pattern
of primary and secondary air over the occupied
zone and induces low velocity secondary air motion
through the occupied zone.
CENTRIFUGAL: In refrigeration, a type of compressor,
which compresses refrigerant vapor by centrifugal
CHANGE OF STATE: Change from one phase, such
as solid, liquid or gas, to another.
CHANGEOVER: The process of switching an air conditioning
system from heating to cooling, or vice versa.
CHARGED PARTICLES: A particle that possesses
at least a unit electrical charge and which will
not disintegrate upon loss of charge. Particle
size, number and sign of unit charges and mobility
characterize charged particles. Also see Ion.
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CHEMISORPTION: the removal of gases from an air
stream by the chemical reaction of the gases with
a chemical agent that is applied to the outside
or distributed through out an adsorbent.
CHILLER: A refrigeration machine that chills
water; the evaporator section of such a machine.
CHROMATOGRAPH: An instrument that can separate
and analyze mixtures of chemical substances.
CLADOSPORIUM: a genus of fungal species commonly
found in indoor and outdoor air. they pose little
problem except in very high concentrations.
CLO VALUE: A numerical representation of a clothing
ensemble's thermal resistance. 1 Clo = 0.88 ft2hoF/Btu
COCARCINOGEN: an agent that acts in conjunction
with another agent to induce cancer.
COIL: A cooling or heating element made of pipe
COLD DECK: The cooling section of a multizone
system; includes cooling coil and duct.
COLONY: A population of cells growing on the surface
of a solid medium; can be seen with the naked
COLORIMETRY (COLORIMETRIC): The term applied
to all chemical analysis techniques involving
reactions in which a color is developed when a
particular contaminant is present in the sample
and reacts with the collection medium. The resultant
color intensity is measured to determine the contaminant
COMBUSTION: The act or process of burning.
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COMFORT CHART: A chart showing effective temperatures
with dry-bulb temperatures and humiditys
(and sometimes air motion) by which the effects
of various air conditions on human comfort may
COMFORT ZONE: (Average) the range of effective
temperatures over which the majority (50 percent
or more) or adults feel comfortable; (extreme)
the range of effective temperatures over which
one or more adults feel comfortable.
COMPOUND: A substance composed of two or more
elements joined according to the laws of chemical
combination. Each compound has its own characteristic
properties different from those of its constituent
COMPRESSOR: The pump that provides the pressure
differential to cause fluid to flow and in the
pumping process increases pressure of the refrigerant
to the high side condition. The compressor is
the separation between low side and high side.
CONCENTRATION: The quantity of one constituent
dispersed in a defined amount of another.
CONDENSATE: Water which has condensed from vapor,
either on the outside of a cooling or dehumidifying
coil, or on the inside of a steam heating coil.
CONDENSATION: Process of changing a vapor into
liquid by extracting heat. Condensation of steam
or water vapor is effected in either steam condensers
or dehumidifying coils, and the resulting water
is called condensate.
CONDENSER: The heat exchanger in which the heat
absorbed by the evaporator and some of the heat
of compression introduced by the compressor are
removed from the system. The gaseous refrigerant
changes to a liquid, again taking advantage of
the relatively large heat transfer by the change
of state in the condensing process.
CONDITIONED AIR: the air that had been heated,
cooled, humidified, or dehumidified to maintain
an interior space within the comfort zone
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CONSTANT AIR VOLUME (CAV): A supply air system
that holds the airflow constant but varies the
supply air temperature to compensate for the thermal
load in the space.
CONTAMINANT: An unwanted airborne constituent
that may reduce acceptability of the air.
CONTROL: A device for regulation of a system
or component in normal operation, manual or automatic.
If automatic, the implication is that it is responsive
to changes of pressure, temperature, or other
property whose magnitude is to be regulated.
CONTROL DIAGRAM (LADDER DIAGRAM): A diagram that
shows the control scheme only. Power wiring is
not shown. The control items are shown between
two vertical lines; hence, the name-ladder diagram.
CONTROL POINT: The value of the controlled variable
that the controller operates to maintain.
CONTROLLED DEVICE: One that receives the converted
signal from the transmission system and translates
it into the appropriate action in the environmental
system. For example: a valve opens or closes to
regulate fluid flow in the system.
CONTROLLER: A device which senses temperature
and adjusts a damper or valve accordingly.
CONVECTION: Transfer of heat by natural movement
of fluid or air.
COOLING COIL: An arrangement of pipe or tubing
that transfers heat from air to a refrigerant
COOLING EFFECT, SENSIBLE: Difference between
the total cooling effect and the dehumidifying
effect, usually in watts (Btuh).
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COOLING EFFECT, TOTAL: Difference between the
total enthalpy of the dry air and water vapor
mixture entering the cooler per hour and the total
enthalpy of the dry air and water vapor mixture
leaving the cooler per hour, expressed in watts
COOLING, EVAPORATIVE: Involves the adiabatic
exchange of heat between air and water spray or
wetted surface. The water assumes the wet-bulb
temperature of the air, which remains constant
during its traverse of the exchanger.
CORE AREA: The total plane area of the portion
of a grille, face or register bounded by a line
tangent to the outer opening through which air
can pass. The core area is less than the register
size. Example, a 14X8 register may have a core
that is 1" less than the listed size, therefore,
the core area is 13X7=91 sq. in.
COUNTERFLOW: In heat exchange between two fluids,
opposite direction of flow, coldest portion of
one meeting coldest portion of the other.
CURTAIN WALL: An exterior wall that does not
carry a load such as a window wall.
CUBIC CENTIMETER (cc): Cubic centimeter, a volumetric
measurement that is also equal to one milliliter
CUBIC METER (m³): A measure of volume in
the metric system.
CURIE: A measure of the rate at which a radioactive
material decays. The radioactivity of one gram
of radium is a curie. It is named for Pierre and
Marie Curie, pioneers in radioactivity and discoverers
of the elements radium, radon, and polonium. One
curie corresponds to 37 billion disintegrations
CYCLING: Turning on and off; for energy conservation,
done at predetermined intervals, or when the power
usage is high.
CYCLONE SEPARATOR: A dust-collecting device that
has the ability to separate particles by size.
Typically used to collect respirable dust samples.
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