LEVEL MEASUREMENT

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LEVEL MEASUREMENT

• CHAPTER 5

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TOPIC COVERED

• Pressure-Measuring Devices
• Buoyancy sensor
• Float-actuated sensor
• Capacitance sensor
• Criteria For Selecting A Suitable
  Pressure-measuring Instrument
• Sensing element
• Operating range

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OBJECTIVES

• After you study this chapter, you should be able
  to
• Define the level measurement.
• Describe the importance of level measurement.
• Explain the operation of buoyancy sensor and
  relationship between Archimedes Principle and
  level.
• Explain the operation of float-actuated sensor
• Explain the operation of capacitance level sensor
  and relationship between capacitance and level.

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Introduction

• Level a measurement of the height of the free
  surface of the liquid from a fixed datum or
  reference.
• Level accuracy-
• Smoothen the process operation.
• Comply the custom and taxing regulation.
• Level can represent the amount of asset and
  related to money matter
• Tank contains liquid and sometime the solid.
• Sometimes the liquid solidifies, very corrosive,
  and vaporizes create difficulties.

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Assignment 4

• Buoyancy Sensor G1 G3
• Float Actuated Sensor G2 G4
• Capacitance Level Sensor G5 G6
• Due date 23 Feb 2006, Thursday

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To be continued ..
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Buoyancy Sensor

• Buoyancy displacement
• Archimedes Principle
• The amount of liquid expands is equal to the
  force of the buoyancy by weight.
• Partially immersed in a cage or without the cage.
  

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Buoyancy Sensor
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Buoyancy Sensor
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Buoyancy Sensor

• f V(Lw/L)(B)(SG)
• f buoyant force span (Newton)
• V total displacer volume (cm3)
• Lw working length of displacer (mm)
• L total displacer length (mm)
• B a constant (weight of unit volume of water
  9.8 x 10-3 Ncm-3)
• SG specific gravity of the liquid.

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Float-actuated Sensor
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Capacitance Sensor
c e(A/d)e0
A plate area covered by the liquid, d the
distance between the plates e the relative
dielectric constant of the material e0 the
dielectric constant of vacuum/ air 1.0
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Capacitance Sensor
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Criteria for Selecting A Suitable T-measuring
Instrument

• Sensing element
• Operating Range
• Units of length (metric or imperial).
• Units of mass (normally associated with HTG).