Principles of Measurement

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Principles of Measurement
LESSON 1

• Let the Games Begin!

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Objectives

• Measurement of temperature and pressure
• Units of measurement
• Measurement devices

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Purpose of Measuring Devices

• Why essential to proper operation of propulsion
  plants?

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WHAT IS TEMPERATURE?

• An indication of the internal energy contained in
  a substance
• Mono-Atomic Gases Linearly proportional
• Poly-Atomic Gases translational, rotational and
  vibrational kinetic energy.
• Temp is a measure of but not directly
  proportional to internal kinetic energy.

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Measurement of Temperature

• Relative Scales
• Fahrenheit (F)
• Celsius (C)
• Absolute Scales
• Rankine (R)
• Kelvin (K)

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Temperature Relationships

• (F) 9/5(C) 32
• (C) 5/9(F) 32
• (F) (R) 459.67
• (C) (K) 273.15

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Sensors
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Principle of OperationTemperature Devices

• Expansion Thermometers
• Liquid in glass
• Bimetallic
• Filled system/distant reading
• Pyrometers
• Thermocouple
• Resistance
• Radiation and optical pyrometers

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Expansion Thermometer

• Liquid in Glass
• Bimetallic
• Filled System/Distant Reading

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Expansion Thermometer

• Liquid in Glass
• Bimetallic
• Filled System/Distant Reading

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Expansion Thermometer

• Liquid in Glass
• Bimetallic
• Filled System/Distant Reading

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Expansion Thermometer

• Liquid in Glass
• Bimetallic
• Filled System/Distant Reading

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Pyrometers

• Thermocouple
• Resistance
• Radiation and Optical

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Pyrometers

• Thermocouple
• Resistance
• Radiation and Optical

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Pyrometers

• Thermocouple
• Resistance
• Radiation and Optical

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Pyrometers

• Thermocouple
• Resistance
• Radiation and Optical

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Measurement of Pressure

• Definition Force per unit area
• Units of measurement
• Pounds force per square inch (psi)
• Inches Hg or inches H2O (Hg)
• Atmospheres (atm)

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Pressure Relationships

• Gage pressure (PSIG)
• Absolute pressure (PSIA)
• Vacuum pressure (PSIV) or (in Hg)
• Atmospheric pressure (14.7 psi)

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Pressure Relationships

• Absolute Pressure Atmospheric Press.
  Gage Press.
• Vacuum Atmospheric Pressure - Absolute
  Pressure

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Pressure Relationships
30 PSIA
15.3 PSIG
GAGE PRESSURE (PSIG)
ABSOLUTE PRESSURE (PSIA)
Atmospheric Pressure
14.7 PSIA
0 PSIG
(Average at Sea Level)
0 In. Hg
VACUUM (in. Hg)
0 PSIA
29.92 In. Hg
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Operation of Pressure Measuring Devices

• Manometers
• Bourdon tube
• Bellows gage

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Operation of Pressure Measuring Devices

• Manometers
• Bourdon tube
• Bellows gage

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Operation of Pressure Measuring Devices

• Manometers
• Bourdon tube
• Bellows gage

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Operation of Pressure Measuring Devices

• Manometers
• Bourdon tube
• Bellows gage

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Questions?