Chapter 27
In extreme cold, the body attempts to cool down by shutting down circulation to the extremities. TRUE OR FALSE
true
In the summertime, air conditioned buildings are usually kept at temperatures approximately _____ the outside temperature.
10 to 15 degrees below
One pound of air at standard conditions 14.7 psia, 69.8 occupies how much?
13.341 ft squared
Most people are comfortable in an atmosphere with the relative humidity between ______ and the temperature between 70 to 85 degrees.
30 to 70 percent
Degree day calculations are based on a temperature of _____.
65 degrees F
In the cold season, humidity controls are typically set to ______ the conditioned air.
Add humidity to
According to ASHRAE, the process of treating air so as to control simultaneously temperature, humidity, cleanliness, and distribution is called______.
Air conditioning
Which of the following instruments is used to measure air velocity?
Anemometer
______makes up 0.03% to 0.04% of the atmosphere and is absorbed by growing plants.
Carbon dioxide
Long term weather trends for a given region refers to ____.
Climate
Make up air is necessary for fuel burning appliances because oxygen is necessary for ?
Combustion
The volume of air flowing through a duct is calculated in ?
Cubic feet per minute
By dividing the weight of air by the volume it occupies, you can calculate the_______of the air.
Density
When air temperature reaches 100% relative humidity, it is at its ______.
Dew point
Starting at sea level and rising higher in altitude through the troposphere, atmospheric pressure _________.
Drops
The combined effect of dry bulb temperature, wet bulb temperature and air movement that provides an equal sensation of warmth and cold describes the term_____.
Effective temperature
How warm the combination of humidity and temperature feels to an occupant of a space is _______ temperature.
Equivalent
For a building to maintain positive pressure with various fuel burning appliances operating, a ______should be used
Fan or blower
A gas that is very light and is present in most fuels is ?
Hydrogen
An instrument that measures moisture in the air is a what?
Hygrometer
According to Bernoulli's principle, _____ the velocity of air decreases the pressure.
Increasing
The Beaufort scale_____.
Indicates levels of wind velocity
A pitot tube should be used only where the duct is very_____.
Long
Designate are substances that absorb ______ from the air.
Moisture
A hygrometer is an instrument that measures_______.
Moisture in the air
The majority of the atmosphere is composed of?
Nitrogen
Earth's atmosphere contains about 23% ________ by weight.
Oxygen
A ______ chart is a graph of the properties of air.
Psychrometric
The science of studying the thermodynamic properties of air and water vapor is called_____.
Psychrometry
Devices used for measuring high temperatures include the following.
Pyrometers, thermistor thermometers, and thermocouple thermometers
The amount of moisture in an air sample compared to the total amount of moisture the same sample would hold if it were completely saturated at the same temperature defines the term_______.
Relative humidity
In the warm season, humidity controls are typically set to ______ the conditioned air.
Remove humidity from
When radiant heat strikes a surface that is colder than the radiating body, _______.
Some of the radiant heat is absorbed into the colder surface and the radiating body becomes a heat sink
The process of cold air drops and warm air rises resulting in a gradual difference in air temperature from floor to ceiling is known as _____.
Stratification
Which type of anemometer is entirely mechanical?
Swinging vane anemometer
Air with 75% relative humidity contains ________ of the moisture it is capable of holding.
Three fourths
An increase in wind velocity increases the heat loss of a heated structure, thereby impacting the efficiency of a heating system. TRUE OR FALSE
True
At comfortable temperatures, there is no sensation of either warmth or cold TRUE OR FALSE
True
Since dry air prevents rapid evaporation of moisture from a surface, the surface does not cool as quickly as it would with moist air TRUE OR FALSE
True
THe exposure time required for frostbite to occur becomes shorter as wind speed increases. TRUE OR FALSE
True
The amount of moisture that a set volume of air can hold depends on air temperature TRUE OR FALSE
True
Wet bulb temperatures will be lower than dry bulb temperatures at 100% humidity TRUE OR FALSE
True
Changing the air in a building is called_____.
Ventilation
The conditions in the atmosphere refer to _____.
Weather
During the winter months, the _____ is used to describe the combined effect of temperature and wind speed.
Windchill index
