Heat, Temperature, and Pressure Flashcards
Temperature
A word used to describe the level of heat or molecular activity, expressed in Fahrenheit, Ranking, Celsius, or Kelvin units.
Pressure
Force per unit area.
Heat
Energy that causes molecules to be in motion and to raise temperature of a substance.
Atmospheric Pressure
The weight of the atmospheres gases pressing down on the earth. Equal to 14.696 psi at sea level and 70 °F.
Heat Intensity
Another term for temperature.
Conduction
Heat transfer from one molecule to another within a substance or from one substance to another.
Rakine
The absolute Fahrenheit scale with 0 at the point where all molecular motion stops.
Kelvin
A temperature scale where absolute 0 equals 0 or where molecular motion stops at 0. It has the same graduations per degree of change as the Celsius scale.
British Thermal Units (BTU)
The amount (quantity) of heat required to raise the temperature of 1 lb of water by 1 °F.
Forced Convection
The movement of fluid by mechanical means.
Natural Convection
The natural movement of a gas or fluid caused by differences in temperature.
Convection
Heat transfer from one place to another using a fluid.
Sensible Heat
Heat that causes a change in temperature.
Radiation
Passes through air, heating the first solid object with which the heat comes in contact.
Latent Heat
Heat energy absorbed or rejected when a substance is changing state and there is no change in temperature.
Specific Heat
The amount of heat required to raise the temperature of 1 lbs of a substance 1 °F.
Latent Heat of Fusion
The amount of heat energy required to change the state of substance from a liquid to solid or from a solid to a liquid.
Standard Condition
Air at sea level at 70 degrees F when the atmosphere’s pressure is 14.696psia(29.92 in. Hg.). Air at this condition has a volume of 13.33ft^3/lb
Bourbon Tube
C-shaped tube manufactured of thin metal and closed on one end. When pressure is increased inside, it tends to straighten. It is used in a gauge to indicate pressure.
Barometer
A device used to measure atmospheric pressure that is commonly calibrated in inches or millimeters of mercury.
Low-Side Gauge
The gauge that measures the low-side pressure in an air-conditioning or refrigeration system.
High-Side Gauge
A term used to indicate the high pressure or condensing side of the refrigeration system.
High-Pressure Gauge
The gauge used to measure the pressure on the high-pressure side of an air-conditioning or refrigeration system.
Compound Gauge
A gauge used to measure the pressure above and below the atmosphere’s standard pressure. It is a Bourdon tube sensing device and can be found on all gauge manifolds used for air-conditioning and refrigeration service work.
