Building Systems 3 Flashcards
refrigerant
The fluid used for heat transfer in a refrigeration system.
halon
A gaseous, fire-extinguishing medium which smothers fires, often used in automatic systems in computer rooms.
declination
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.
perm
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.
refrigeration
The extraction of heat from
a substance or an unoccupied space to reduce it’s temperature below that of it’s surroundings.
noise
Any undesired sound, also any unwanted disturbance within a useful frequency band.
barometer
An instrument for measuring atmospheric pressure.
stack effect
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.
chill factor
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.
diffuser
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.
DWV
Abbreviation for drain, waste, and vent.
circuit 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.
equinox
Either March 21st (vernal equinox) or September 21st (autumnal equinox), first day of spring (or fall), when night and day are of equal length.
anechoic room
A room whose boundaries absorb all of the sound striking them. It is also known as a free-field room.
barometric damper
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.
turning vanes
Curved baffles inserted in a duct elbow to decrease pressure loss through the elbow.
watt (W)
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.
collector
A device used to collect solar radiation.
PPM
The abbreviation for parts per million.
intensity level
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.
resistance
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.
illumination
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).
room resonance
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.
gate valve
A valve consisting of a sliding plate or gate perpendicular to the flow, intended to be fully open or closed.
vacuum breaker
An automatic valve which admits air into a supply pipe to prevent siphoning polluted water back into the supply.
pilot tube
An instrument used with a manometer or pressure gauge to measure the velocity of air or water in a duct or pipe.
sunspace system
A passive solar system that utilizes a direct gain feature, such as greenhouse or atrium, usually with a thermal storage wall.
evaporative cooling
A cooling process in which water vapor, at a constant wet bulb temperature, is added to air, reducing the dry bulb temperature.
loop vent
A vent which connects from a drain to the stack vent of the soil stack to which the drain is connected.
static pressure
The pressure exerted by a fluid at rest.
rectifier
A device which converts alternating current to direct current and is used to recharge batteries or supply direct current for other purposes.
circular mil
The area of a wire having a diameter of one mil or 1/1000th (0.001) of an inch, used in specifying wire size.
shading coefficient (SC)
The ratio of the solar heat gained through a window with shading devices, such as blinds, to the solar heat gained by a single pane, double strength, clear glass window.
continuous vent
A vent which is a continuation of the trap and drain to which it connects. It is also called an individual vent.
lumen
The unit of visible light emitted by a light source, defined as the amount of light passing through one square foot at a distance of one foot from a one candlepower source.
loudness
The perceived intensity of sound, which depends mainly on the sound pressure, but also on the frequency and waveform of the sound source.
cycles per second (CPS)
A measure of frequency in electric current or acoustics, i.e., the number of cycles per second of a wave or oscillation. The term has been largely replaced by hertz, where 1 cps = 1 Hz.