Building Utilities (Mechanical) Flashcards
A measure of the warmth or coldness of a substance, object, or environment with reference to some standard value.
Temperature
An instrument for measuring temperature, consisting typically of a glass tube with a numbered scale and bulb containing a liquid, such as mercury, that rises and falls with changes in temperature.
Thermometer
The quantity of heat required to raise the temperature of one pound (0.4kg) or water 1 degree F.
British thermal unit
A unit of heat equal to 100,000 British thermal unit.
Therm
A unit of heat equal to the quantity of heat required to raise the temperature of one gram of water 1 degree C at a pressure of one atmosphere, equivalent to 4.186 joules.
Calorie
A unit of heat equal to the quantity of heat required to raise the temperature of one kilogram of water 1 degree C at a pressure of one atmosphere, equivalent to 1000 small calories.
Kilocalorie
A temperature scale in which 32°F represents the freezing point and 212°F the boiling point of water under standard atmospheric pressure.
Fahrenheit scale
A temperature scale divided into 100 degrees, in which 0°C represents the freezing point and 100°C the boiling of water under standard atmospheric pressure.
Celsius scale
An absolute scale of temperature having a zero point of - 273.16°C.
Kelvin scale
A temperature scale based on absolute zero with scale units equal in magnitude to centigrade degrees.
Absolute scale
The hypothetical lowest limit of physical temperature characterized by complete absence of heat, equal to -273.16° C or -459.67°F.
Absolute zero
Temperature as measured on an absolute scale.
Absolute temperature
The base SI unit of temperature equal to 1/273.16 of the triple point of water.
Kelvin
The particular temperature and pressure at which the liquid, gaseous, and solid phases of a substance can exist in equilibrium.
Triple point
The transfer of heat by the circulatory motion of the heated parts of a liquid or gas owing to a variation in density and the action of gravity.
Convection
The transfer of heat from the warmer to the cooler particles of a medium or of two bodies in direct contact, occurring without perceptible displacement of the particles themselves.
Conduction
The process in which energy in the form of waves or particles is emitted by one body, passed through an intervening medium or space, and absorbed by another body.
Radiation
The time rate of heat flow through a unit area of a given material of unit thickness when the temperature difference across the thickness is one unit of temperature.
Thermal conductivity
The time rate of heat flow through a unit area of a given material when the temperature difference across a specified thickness of the material is one unit of temperature.
Thermal conductance
An element of low thermal conductivity placed in an assembly to reduce the flow of heat between highly conductive materials.
Thermal break
The reciprocal of thermal conductance expressed as the temperature difference required to cause heat to flow through a unit area of a material of given thickness at the rate of one heat unit per unit time.
Thermal resistance
A measure of thermal resistance of a given material, used esp. to specify the performance of thermal insulation.
R-value
The time rate of heat flow through a unit area of a building component or assembly when the difference between the air temperature on the two sides of the component or assembly is one unit of temperature.
Thermal transmittance
A measure of the thermal transmittance of a building component or assembly, equal to the reciprocal of the total R-value of the component or assembly.
U-value