Temperature Measurement

Course Number: 777

This course defines terms and units in thermal measurement and describes the operation of RTDs, wheatstone bridges, thermistors, thermocouples, and several kinds of thermometers. It explains the principles of pyrometry and the operation of narrowband, broadband, and bandpass pyrometers. It concludes with a lesson on calibration standards and typical methods for calibrating and testing many kinds of temperature-measuring instruments.

Recommended Contact Hours - 8

Chapter 1: Temperature Measurement Principles and Indicators

Topics: Temperature and temperature scales; Heat; Change of state; Measuring instruments; Color change and melting point indicators

Learning Objectives:

• Define thermal energy and explain the relationships among thermal energy, heat, and temperature in a substance.
• Correlate changes in temperature with changes in a substance's physical state.
• Compare four temperature scales, and convert temperature readings from one scale to another.
• Explain how primary and secondary temperature calibration standards are used.
• Describe various temperature-measuring devices and contrast thermometers and pyrometers.

Chapter 2: Bimetallic & Fluid-Filled Temperature Instruments

Topics: Bimetallic, liquid-in-glass, and filled-system thermometers; Liquid- and gas-filled systems; Vapor-pressure systems; Capillary and bourdon tubes; Temperature transmitters

Learning Objectives:

• Discuss the physical characteristics and operation of bimetallic thermometers.
• Describe how liquid-in-glass thermometers are constructed and how they operate.
• Compare liquid-, gas-, and vapor-filled systems and discuss their advantages and disadvantages.
• Explain how a mercury thermometer operates.

Chapter 3: Electrical Instruments

Topics: Resistance thermometers; Wheatstone bridge circuits; RTD elements; Thermistors; Thermocouples; Compensation

Learning Objectives:

• Discuss the relationship between temperature and electrical resistance.
• Describe the function of RTD bridge circuits and explain how to calculate lead-wire errors.
• Compare the accuracy, response time, stability, and circuit complexity of RTDs and thermistors.
• Describe the operation of a thermocouple and explain how to compensate for changes in the reference junction temperature.

Chapter 4: Pyrometry

Topics: Principles; Effects of emittance and temperature; Wavelength of radiated energy; Pyrometers

Learning Objectives:

• Discuss the principles that govern noncontact thermal measurements.
• Define electromagnetic radiation and emittance.
• Discuss the characteristics of a blackbody.
• Describe the effects of temperature and emittance on radiation intensity.
• Describe the operation of optical and radiation pyrometers.

Chapter 5: Temperature Instrument Maintenance & Calibration

Topics: Calibration standards; Instrument inspections; Controlled-temperature environments; Triple-point and ice baths; Calibration and testing

Learning Objectives:

• Compare and define primary, secondary, and working calibration standards.
• Describe typical testing procedures for temperature-measuring instruments.
• Describe routine maintenance and calibration procedures for temperature-measuring instruments.
• Explain how to use controlled-temperature environments-ice baths, triple-point baths, fluid baths, and fluidized baths.
• Explain how to calibrate liquid-in-glass thermometers, thermocouples, resistance thermometers, and pyrometers.