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Lesson 2 TEMPERATURE AND PRESSURE MEASUREMENTS. DEFINE the thermodynamic properties temperature and pressure. DESCRIBE the Fahrenheit, Celsius, Kelvin, and Rankine temperature scales including: Absolute zero temperature The freezing point of water at atmospheric pressure
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Lesson 2TEMPERATURE AND PRESSURE MEASUREMENTS • DEFINE the thermodynamic properties temperature and pressure. • DESCRIBE the Fahrenheit, Celsius, Kelvin, and Rankine temperature scales including: • Absolute zero temperature • The freezing point of water at atmospheric pressure • The boiling point of water at atmospheric pressure • CONVERT temperatures between the Fahrenheit, Celsius, Kelvin, and Rankine scales. • DESCRIBE the relationship between absolute pressure, gauge pressure, and vacuum. • CONVERT pressures between the following units: • Pounds per square inch • Inches of water • Inches of mercury • Millimeters of mercury • Microns of mercury
Temperature • A measure of the molecular activity of a substance • The greater the movement of molecules, the higher the temperature. • Can be used to predict the direction of heat transfer
Temperature Scales • Fahrenheit (F) • 320 F – Water Freezing Point • 2120 F – Water Boiling Point • Celsius (C) • 00 C – Water Freezing Point • 1000 C – Water Boiling Point • °F = 32.0 + (9/5)°C • °C = (°F - 32.0)(5/9)
Temperature Scales (cont) • Rankine (R) • Fahrenheit plus 4600 (absolute scale for Fahrenheit) • Kelvin (K) • Celsius plus 2730 (absolute scale for Celsius)
Pressure • A measure of the force exerted per unit area on the boundaries of a substance (or system) • Is uniform inside an enclosed container • Is frequently measured in units of lbf/in2 (psi).
Pressure Scales • Absolute Pressure - Measured relative to a perfect vacuum (psia) • Gauge Pressure - Measured relative to atmospheric pressure (psig) • Vacuum – Any pressure that is below atmospheric pressure (14.7 psi)
Pressure Relationships • Pabs = Patm+ Pgauge • Pabs = Patm- Pvac
Pressure Conversion Factors • 14.7 psia = 408 inches of water • • 14.7 psia = 29.9 inches of mercury • • 1 inch of mercury = 25.4 millimeters of mercury • • 1 millimeter of mercury = 103 microns of mercury