Flashcards in Building Systems 3 Deck (103)
A gaseous, fire-extinguishing medium which smothers fires, often used in automatic systems in computer rooms.
The fluid used for heat transfer in a refrigeration system.
The 23.5° tilt of the earth's axis relative to a line perpendicular to the plane of the Earth's orbit. This tilt is responsible for the seasons.
The unit of permeability for a given material, expressing the resistance of the material to the penetration of moisture. One perm is equal to the flow of one grain of water vapor through one square foot of surface area per hour with a pressure difference of one inch of mercury.
The extraction of heat from
a substance or an unoccupied space to reduce it's temperature below that of it's surroundings.
Any undesired sound, also any unwanted disturbance within a useful frequency band.
An instrument for measuring atmospheric pressure.
The tendency of a gas or air to rise in a vertical shaft because it's density is lower than that of the surrounding gas or air. It is also called chimney effect.
A fictitious temperature assigned to a combination of actual temperature and wind velocity which has the same physiological effect as still air at the chill factor temperature. It is also known as wind chill index.
A device through which the air from a duct enters a room, or a device through which the light from a fixture enters a room.
Abbreviation for drain, waste, and vent.
In sanitary drainage, any vent which serves two or more traps.
heat of vaporization
The heat given off by a vapor condensing to a liquid, or the heat absorbed by a liquid evaporating to a gas, without a change in temperature.
Either March 21st (vernal equinox) or September 21st (autumnal equinox), first day of spring (or fall), when night and day are of equal length.
A room whose boundaries absorb all of the sound striking them. It is also known as a free-field room.
A balanced air valve positioned so as to admit air to the flue or stack of a furnace in order to maintain a constant amount of draft. It is also called a draft regulator.
Curved baffles inserted in a duct elbow to decrease pressure loss through the elbow.
The basic unit of electrical power, equal to the product of volts and amperes in direct current systems, equal to 3.41 Btuh.
power level (pwl)
The logarithmic expression for the acoustical power at the source of a sound. It is also known as acoustic power level.
A device used to collect solar radiation.
The abbreviation for parts per million.
The intensity of sound at a given location, measured in watts per square meter, or more commonly in decibels where the reference level is 10-12 watts/meter squared or 10-16 watts/cm squared.
A measure of the tendency of an electric circuit to restrict the flow of current, or the ratio of voltage to current in a conductor or closed circuit. The unit of resistance is the ohm.
The intensity of light falling on a surface, usually expressed in footcandles.
noise reduction coefficient (NRC)
A one-number rating system giving the average sound absorption coefficient of a material at frequencies of 250, 500, 1000, and 2000 Hz.
sensible heat ratio (SHR)
The ratio of sensible heat to enthalpy (total heat).
The phenomenon which occurs when sounds in a room that are within a narrow band of frequencies tend to sound louder than sounds of other frequencies.
A valve consisting of a sliding plate or gate perpendicular to the flow, intended to be fully open or closed.
An automatic valve which admits air into a supply pipe to prevent siphoning polluted water back into the supply.