Measurement

Principles of Principles of MeasurementMeasurement

Let the Games Let the Games Begin!Begin!

LESSON 1

ObjectivesObjectives• Measurement of Measurement of

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

ReferencesReferences

• Introduction to Naval Introduction to Naval EngineeringEngineering

• Principles of Naval EngineeringPrinciples of Naval Engineering

Purpose of Measuring Purpose of Measuring DevicesDevices

• Why essential to proper Why essential to proper operation of propulsion operation of propulsion plants?plants?

WHAT IS WHAT IS TEMPERATURE?TEMPERATURE?

• An indication of the internal energy An indication of the internal energy contained in a substancecontained in a substance• Mono-Atomic Gases: Linearly Mono-Atomic Gases: Linearly

proportionalproportional• Poly-Atomic Gases: translational, Poly-Atomic Gases: translational,

rotational and vibrational kinetic rotational and vibrational kinetic energy.energy.

• Temp is a measure of but not Temp is a measure of but not directly proportional to internal directly proportional to internal kinetic energy.kinetic energy.

Measurement of Measurement of TemperatureTemperature

• Relative ScalesRelative Scales• Fahrenheit (°F)Fahrenheit (°F)• Celsius (°C) Celsius (°C)

• Absolute ScalesAbsolute Scales• Rankine (°R)Rankine (°R)• Kelvin (K)Kelvin (K)

Temperature Temperature RelationshipsRelationships

(°F) = 9/5*(°C) +32(°F) = 9/5*(°C) +32

(°C) = 5/9*[(°F) –32](°C) = 5/9*[(°F) –32]

(°F) = (°R) – 459.67(°F) = (°R) – 459.67

(°C) = (K) – 273.15(°C) = (K) – 273.15

Measurement of Measurement of PressurePressure

• Definition: Force per unit areaDefinition: Force per unit area• Units of measurementUnits of measurement

• Pounds force per square inch Pounds force per square inch (psi) (psi)

• Inches Hg or inches HInches Hg or inches H22O (“Hg)O (“Hg)• Atmospheres (atm)Atmospheres (atm)

Pressure RelationshipsPressure Relationships

• Gage pressure (PSIG)Gage pressure (PSIG)• Absolute pressure (PSIA)Absolute pressure (PSIA)• Vacuum pressure (PSIV) or (in Vacuum pressure (PSIV) or (in

Hg)Hg)• Atmospheric pressure (14.7 Atmospheric pressure (14.7

psi)psi)


Absolute Pressure = Atmospheric Absolute Pressure = Atmospheric Press. + Press. + Gage Gage Press.Press.

Vacuum = Atmospheric Pressure - Vacuum = Atmospheric Pressure - Absolute Absolute PressurePressure


Atmospheric Pressure(Average at Sea Level)

VACUUM(in. Hg)

GAGE PRESSURE

(PSIG)ABSOLUTE PRESSURE

(PSIA)

0 PSIA

14.7 PSIA

30 PSIA

0 PSIG

0 In. Hg

29.92 In. Hg

15.3 PSIG

Principle of OperationPrinciple of OperationTemperature DevicesTemperature Devices

• Expansion ThermometersExpansion Thermometers• Liquid in glassLiquid in glass• BimetallicBimetallic• Filled system/distant readingFilled system/distant reading

• PyrometersPyrometers• ThermocoupleThermocouple• ResistanceResistance• Radiation and optical pyrometersRadiation and optical pyrometers

Expansion Expansion ThermometerThermometer

• Liquid in GlassLiquid in Glass• BimetallicBimetallic• Filled Filled

System/Distant System/Distant ReadingReading

PyrometersPyrometers

• ThermocoupleThermocouple• ResistanceResistance• Radiation and OpticalRadiation and Optical

Operation of Pressure Operation of Pressure Measuring DevicesMeasuring Devices

• ManometersManometers• Bourdon tubeBourdon tube• Bellows gageBellows gage

QuestionQuestions?s?

Measurement

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