Flow Measurement

Table of Contents

Chapter 1: Properties of Fluid Flow

Topics: Fluids in motion; Establishing a pressure difference; Indicating flow; Factors affecting flow rate; Reynolds number

Learning Objectives:

• Explain the difference between density and relative density (specific gravity).
• Define fluid velocity, viscosity, and volume flow rate.
• Describe laminar flow and turbulent flow.
• Explain how static head, friction head, and velocity head differ from each other.
• Explain how pipe size, pipe friction, and fluid viscosity affect the measurement of fluid flow.

Chapter 2: Primary Measuring Devices

Topics: Flow measurement in filled pipes; Restricting flow; Pressure drop; Orifice plates; Flow nozzles; Turndown and rangeability; Pipe taps

Learning Objectives:

• Describe direct and indirect flow measurement methods.
• Describe how a primary device creates a differential pressure.
• Give at least three examples of common primary devices and explain how each works.
• Describe the significant features of orifice plates and explain their functions.
• Discuss the conditions that determine the length of straight pipe required for each kind of primary flowmeter.

Chapter 3: Secondary Measuring Devices

Topics: Manometers; Liquid pressure measurement; Hazards of mercury; Bellows meter; DP transmitter; Target meter; Deadweight tester

Learning Objectives:

• Explain why both accuracy and precision are required in a secondary measuring device.
• Describe how an inclined manometer differs from a conventional U-tube manometer.
• Explain how to calibrate dry and wet manometers.
• Give examples of secondary measuring devices and explain how they work.
• Explain how to calibrate a differential pressure transmitter and discuss the different outputs available.

Chapter 4: Variable-Area Instruments

Topics: Rotameters; Measuring gas flow; Specific gravity, pressure, and temperature; Float and tube shapes; Piston, vane, and special meters

Learning Objectives:

• Discuss the similarities and differences between rotameters and orifice instruments.
• Compare the benefits of linear and nonlinear scales and explain how a square-root extractor is used.
• Explain how calibration, relative density, viscosity, and temperature affect rotameter readings.
• Describe how changes in the pressure, temperature, and relative density of a gas affect the ability of a rotameter to measure its flow rate.
• Discuss the operation of piston- and vane-type flowmeters and explain why armored rotameters and orifice-plug flowmeters are used.

Chapter 5: Open-Channel Flow Devices

Topics: The weir; Notch shapes; Weir precautions and maintenance; Using nomographs to calculate flow; Flume terminology and uses; Ultrasonic and capacitance level sensors

Learning Objectives:

• Describe the structure and function of a weir.
• Identify various weir components-notch, crest, pond, bulkhead, and head gauge.
• Describe the construction and function of a Parshall flume.
• Identify the parts of a Parshall flume-crest, throat, stilling well, and diverging and converging sections.
• Explain how ultrasonic and capacitance-level measuring devices are used to detect open-channel flow rates.

Chapter 6: Positive-Displacement Meters

Topics: Piston and rotating-vane meters; Nutating-disk, lobed impeller, oval, and helix flowmeters; Dry-gas bellows meter; Calibration

Learning Objectives:

• Describe the advantages and disadvantages of positive-displacement meters.
• Describe the operation of the reciprocating piston meter and the oscillating piston meter.
• Describe the operating principles of the sliding-vane rotary meter and the nutating-disk meter.
• Identify the elements in lobed impeller, oval, and helical flowmeters.
• Explain the operation of a dry-gas bellows meter.
• Discuss the calibration of positive-displacement meters.

Chapter 7: Turbine and Magnetic Flowmeters

Topics: Turbine flowmeter types, components, principles, construction, and installation; Magnetic flowmeter construction, output, and installation

Learning Objectives:

• Describe the operating principles governing turbine flowmeters.
• Discuss the construction of turbine flowmeters.
• Discuss the advantages and disadvantages of turbine flowmeters.
• Describe the operating principle governing magnetic flowmeters.
• Describe significant advantages and disadvantages of magnetic flowmeters.

Chapter 8: Specialized Flowmeters

Topics: Vortex-precession and vortex-shedding meters; Mass, thermal, and ultrasonic flowmeters; Heat-transfer, immersion-probe, and hot-wire meters

Learning Objectives:

• Discuss in detail the operation of a vortex-precession meter.
• Define the term vortex-shedding and describe vortex-shedding meters and their output system.
• Explain mass flow and describe a Coriolis meter.
• Describe three kinds of thermal flowmeters.
• Describe the Doppler-shift, beam-deflection, and frequency-difference methods used by ultrasonic flowmeters.

Chapter 9: Metering the Flow of Solid Particles

Topics: Volumetric and mass flowmeters for solids; Belt-type solids meters; Slurries; Constant-weight feeders

Learning Objectives:

• Define the term meter factor and explain how it is obtained.
• Explain the operation of a mass flowmeter.
• Discuss the operation of the belt-type solids meter.
• Describe how a slurry is made, transported, and metered.
• Discuss the continuous measurement and control of the flow of solid material in a process.

Chapter 10: Installation and Maintenance of Flow Instruments

Topics: Primary flow elements; Pressure taps; Piping, fittings, and valves; Electrical hookup; Maintenance precautions; Preventive maintenance; Calibration

Learning Objectives:

• Describe components of a differential flow measurement system.
• List guidelines for correct installation.
• Discuss the principles of thorough and safe instrument maintenance.
• List the steps in instrument calibration.
• Discuss the basic rules of safety in instrument servicing.

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