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GLOSSARY ‘B’ to ‘C’
BACILLUS: A rod-shaped bacterium. BACTERIOCIDAL: Able to kill bacteria BACTERIA: Microscopic organisms living in soil, water, organic matter, or the bodies of plants and animals characterized by lack of a distinct nucleus and lack of ability to photosynthesize. Singular: Bacterium. BACTERICIDE: Any agent that destroys bacteria. BALANCING BY STATIC PRESSURE: Method of designing local exhaust system ducts by selecting the duct diameters that generate the static pressure to distribute airflow without dampers. BAROMETER: Instrument for measuring atmospheric pressure. BENIGN: Not malignant. A benign tumor is one which does not metastasize or invade tissue. Benign tumors may still be lethal, due to pressure on vital organs. BENZENE: A major organic intermediate and solvent derived from coal or petroleum. The simplest member of the aromatic series of hydrocarbons. BERYL: A silicate of beryllium and aluminum. BETA PARTICLE (BETA RADIATION): A small electrically charged particle thrown off by many radioactive materials. It is identical with the electron. Beta particles emerge from radioactive material at high speeds. BIOAEROSOL: An airborne organic contaminant that is either generated by or is itself a living organism; examples of bioaerosols are fungi, bacteria, viruses, protozoa, pollen, animal dander, insect emanations, microbial endotoxins, and human skin scales. BIOHAZARD: A combination of the words biological hazard. Organisms or products of organisms that present a risk to humans. BOILER: A closed container used to heat water or to make steam. BRITISH THERMAL UNIT (BTU): The Btu is defined as the heat required to raise the temperature of one pound of water from one degree F. BRONCHIAL TUBES: Branches or subdivisions of the trachea (windpipe). A bronchiole is a branch of bronchus, which is a branch of the windpipe. BTU: British Thermal Unit - a measure of heat quantity. BYPASS: A pipe or duct, usually controlled by valve or damper, for conveying a fluid around an element of a system. C.F.M.: A measure of volume of air in cubic feet per minute. 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 acid-base balance of the body is affected by the level of carbon dioxide in the blood and other tissues. 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, soda water. 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 of cancer. CARCINOMA: The generalized group of cancers that develop in epithelial cells. CARRIER: A person in apparent good health who harbors a pathogenic microorganism. CARRIER GAS: The mixture of gases which contains and moves the contaminant material. Components of the carrier gas are not considered to cause air pollution or react with the contaminant material. 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 force. 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 which possesses at least a unit electrical charge and which will not disintegrate upon loss of charge. Charged particles are characterized by particle size, number and sign of unit charges and mobility. Also see Ion. CHILLER: A refrigeration machine that chills water; the evaporator section of such a machine. CHROMATOGRAPH: An instrument which can separate and analyze mixtures of chemical substances. CLO VALUE: A numerical representation of a clothing ensemble's thermal resistance. 1 Clo = 0.88 ft2hoF/Btu (0.155 m2K/W). COIL: A cooling or heating element made of pipe or tubing. 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 eye. 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 concentration. COMBUSTION: The act or process of burning. COMFORT CHART: A chart showing effective temperatures with dry-bulb temperatures and humidities (and sometimes air motion) by which the effects of various air conditions on human comfort may be compared. 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 elements. COMPRESSOR: The pump which 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. CONSTANT AIR VOLUME (CAV): A supply air system that holds the air flow 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 which the controller operates to maintain. CONTROLLED DEVICE: One which 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 which transfers heat from air to a refrigerant or brine. COOLING EFFECT, SENSIBLE: Difference between the total cooling effect and the dehumidifying effect, usually in watts (Btuh). 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 (Btuh). 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 which 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 (mL). 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 per second. 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 which has the ability to separate particles by size. Typically used to collect respirable dust samples.
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