B10 Flashcards
Absolute humidity
The mass of moisture (i.e. water vapour) present in one kilogram of an air/moisture mixture. The measurement unit for absolute humidity is kg/kg
Air conditioning
The simultaneous control of the physical and the chemical conditions of the atmosphere within a structure. This is achieved by affecting some or all of the following air conditions: temperature, humidity, motion, distribution, pressure, and filtration (dust, bacteria, odours, toxic gases, and ionization.)
Air diffuser
Air distribution outlet or grille designed to direct airflow into desired patterns.
Air washer
A mechanical device placed in an air stream to cool, clean, humidify, or dehumidify the air.
Air handling unit
A machine comprised of a fan, a filter, a heater, a cooler, and a humidifier,
used to supply conditioned air in an HVAC system.
Axial flow fan
A fan that supplies air parallel to the direction of the fan shaft.
Centrifugal fan
A fan that supplies air perpendicular to the fan shaft. Centrifugal fans are classified according to the shape and design of the fan blades: backward inclined, forward curved, backward inclined with airfoil blades, and radial blades.
Charged media air cleaner
An electrically charged fibreglass or cellulose filter mat, installed in an air stream, which efficientlv removes particulate matter.
Conduction
The transmission of heat through and by means of matter unaccompanied by any obvious motion of the matter.
Convection
Transfer of heat by means of movement or flow of a liquid or gas.
Damper
Device to control air flow
Dew point
The temperature at which air subjected to cooling becomes saturated and below which the water vapour will begin to condense out of the moist air.
Dry air filter
A matting of fine tangled fibrous material, placed across an air duct or plenum, to remove particulate from an air stream.
Dry bulb temperature
The temperature of a gas or mixture of gases indicated by an accurate thermometer when there is no latent heat flow from the thermometer.
Duct system
In HVAC systems, a collection of large interconnected ducts, fans, filters,
coils, dampers, and louvres for moving air to and from conditioned spaces.
Effective temperature (ET)
The overall effect of air temperature, humidity, and air movement on human comfort.
Electronic air cleaner
An air purification device that imparts an electrical charge to particles in an air stream causing them to collect on an oppositely charged plate
Evaporation
Term applied to the changing of a liquid to a gas. Heat is absorbed in this process.
Fire damper
A steel frame equipped with steel dampers, which fit tightly in the casing when closed. The damper is activated by the melting of a fusible link
Fixed louvres
A non-adiustable assembly of blades that direct airflow.
High efficiency particle air (HEPA)
An air filter capable of removing particles as small as 0.3 micron in diameter with 99% efficiency. They are commonly used in hospitals, laboratories, and other facilities requiring supply air nearly free of particles.
Humidity
The presence of moisture in the air
HVAC stands for
Heating, ventilation, and air conditioning
Makeup air
In an HVAC system, the fresh air supplied to an occupied space to replace stale, oxvgen depleted, and possibly smelly air in the building or system