Level Measurement

Effect of Tank Design on Accuracy of Level Measurement

In many industrial applications and processes, including as manufacturing, chemical processing, oil and gas, water treatment, and others, level measuring is a crucial component. In order to monitor processes, manage inventories, and ensure secure and effective operations, level readings must be accurate. 

The tank’s design has a big impact on the accuracy and reliability of level measurements. Let’s examine each of the key elements in greater detail:

Effect of Tank Design on Accuracy of Level Measurement 1

Tank Shape and Geometry

  • Tanks come in different shapes and geometries, such as cylindrical, spherical, rectangular, or irregular.
  • Cylindrical tanks are commonly used due to their simple design, providing consistent and predictable level measurements.
  • Irregular shapes or complex geometries may introduce measurement errors due to uneven distribution of contents, leading to variations in measurements.

Tank Size and Height

  • The size and height of the tank can affect the accuracy of level measurement.
  • Due to the relative greater influence of sensor tolerances, readings of smaller tanks may have higher percentage errors.
  • Taller tanks can introduce hydrostatic pressure variations, impacting measurement accuracy and requiring compensation for pressure effects.

Construction Material

  • The tank’s material can affect the accuracy of level measuring.
  • Non-metallic or non-conductive materials, for example, can have an impact on the performance of level measurement technologies such as capacitance or conductive sensors.
  • Due to electromagnetic phenomenon, metal tanks may cause signal interference for several non-contact level measuring devices.

Tank Wall Thickness

  • The thickness of the tank walls can impact level measurement accuracy.
  • Thick walls can reduce signal penetration for certain technologies, leading to less precise measurements.
  • For ultrasonic or radar-based measurements, thick walls may also introduce reflections and echoes that affect the accuracy of readings.

Effects of Sloshing and Waves

  • The presence of sloshing and waves in the tank can result in measurement errors.
  • These effects can be most noticeable in tanks containing free surface liquids, such as gasoline tanks on moving vehicles or ships.
  • In such instances, specific strategies or technologies may be necessary to adjust for sloshing effects.

Pressure and temperature

  • To achieve accurate level measurements, tank design should take temperature and pressure variations into account.
  • Temperature changes might cause the liquid to expand or contract, affecting the observed level.
  • Thermal influences might cause the tank to expand or contract. This can have a big influence on level-based measurements instead of volume measurements since an extended tank might have more fuel in it at a certain midpoint than it would have at the same midpoint without expansion.
  • High-pressure conditions can have an impact on the performance of some measurement devices, requiring pressure corrections.

Properties of Liquids

  • The physical qualities of the liquid being measured can have an impact on the accuracy of the level measurement.
  • Certain level measurement devices may be hampered by liquids with high viscosity or low dielectric constants.
  • Proper measuring equipment selection can account for these qualities and provide reliable measurements.
  • The expansion of the shell caused on by the substance contained

Fumes and Vapors

  • Tanks containing volatile liquids can emit vapors and fumes that can interfere with certain level measurement systems, such as ultrasonic or optical sensors.
  • To ensure measurement accuracy, proper ventilation or the use of vapor-resistant sensors may be required.

Calibration and Sensor Positioning

  • Accurate level measurements require proper calibration and sensor positioning.
  • Calibration ensures that the readings correlate to the liquid’s real level.
  • To avoid incorrect readings, sensor placement should take into account the tank’s internal features as well as potential obstacles.

Agitators and Baffles

  • Tanks containing baffles and agitators might have an impact on level measuring accuracy.
  • Wave reflections caused by baffles can result in misleading level measurements during measuring.
  • Agitators can cause disturbances on the liquid surface, altering its stability and introducing measuring inaccuracies.

Maintenance and Human Error

  • Human error during tank installation or maintenance can result in inaccurate level measurement.
  • To maintain sustained accuracy, regular maintenance and calibration checks are required.
  • Human errors can be reduced by properly training workers involved in tank operations and level measurement.

Environmental Aspects

  • External environmental conditions can have an impact on the accuracy of level measurement.
  • Sensor performance can be impacted by vibrations, electromagnetic interference, and temperature variations.
  • Sensor shielding or isolation may be required in settings with severe electromagnetic interference.

Technology for Level Measurement

  • The level measurement system selected should be compatible with the tank design and intended application.
  • Ultrasonic, radar, capacitance, and hydrostatic technologies all have variable degrees of the suitability for various tank designs.
  • Each approach has advantages and disadvantages, and the best option is determined by criteria such as tank size, contents, and environmental conditions.

Control System Integration

  • The accuracy of level measurement should be in line with the overall control system requirements.
  • Disagreements in level readings may result in inefficiencies in process control or inventory management.
  • Monitoring and communication between level sensors and control systems in real time can help to optimize operations.

Concerns Regarding Safety

  • To avoid spilling or overfilling, tank design should prioritize safety, which can affect level measuring accuracy.
  • Even in critical circumstances, proper safety procedures can assure reliable and precise measurements.
  • In the event of incorrect level readings, safety shut-off mechanisms can prevent catastrophic events.

Sundareswaran Iyalunaidu

With over 24 years of dedicated experience, I am a seasoned professional specializing in the commissioning, maintenance, and installation of Electrical, Instrumentation and Control systems. My expertise extends across a spectrum of industries, including Power stations, Oil and Gas, Aluminium, Utilities, Steel and Continuous process industries. Tweet me @sundareshinfohe

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