Level gauges are widely used in industrial automation to measure liquid levels in tanks and vessels. In many industries, the accuracy of level measurement directly affects production efficiency, process stability, and safety. However, in real applications, level gauge readings sometimes fluctuate, which may result in inaccurate control, equipment malfunction, or even safety hazards.
This document summarizes the common causes of level gauge reading fluctuations and provides practical solutions.
1. Common Causes of Reading Fluctuations
1.1 Variations in Liquid Properties
Viscosity changes: High-viscosity liquids (e.g., oils, resins) may restrict free movement or signal stability, leading to fluctuating readings.
Temperature changes: Liquid temperature affects density and volume expansion, particularly impacting float-type and capacitive level gauges.
Foam and bubbles: Fermentation liquids or reaction fluids tend to produce foam or bubbles, which interfere with sensors and cause unstable signals.
1.2 Unstable Liquid Interfaces
Strong liquid flow: Turbulence in the vessel or pipeline can disturb the liquid surface, affecting accuracy.
External disturbances: Wind, gas release, or mechanical vibration may cause liquid surface oscillations.
1.3 Installation and Environmental Factors
Incorrect installation angle: Non-vertical or misaligned installation leads to measurement errors.
Vibration and mechanical interference: Nearby pumps or fans may transmit vibration, especially problematic for float-type gauges.
1.4 Electrical and Signal Interference
Electromagnetic interference (EMI): Radar, ultrasonic, and capacitive level gauges are sensitive to EMI.
Wiring and power supply issues: Loose wiring, poor contact, or unstable power causes signal fluctuation.
1.5 Instrument-Related Issues
Sensor aging or damage: Prolonged use reduces accuracy and stability.
Calibration errors: Lack of proper calibration results in inaccurate readings.
2. Solutions to Reading Fluctuations
2.1 Improving Liquid Conditions
Control temperature and viscosity by heating, cooling, or dilution.
Remove foam and bubbles using defoaming devices, stabilizers, or optimized flow conditions.
2.2 Liquid Interface Management
Reduce flow interference by adding baffles, calming sections, or stilling wells.
Stabilize liquid surface using wave dampeners around the level gauge.
2.3 Optimizing Installation and Environment
Ensure correct alignment: Install vertically or parallel to the liquid surface.
Reduce vibration by relocating instruments or using vibration-damping mounts.
2.4 Electrical and Signal Stability
Use shielding and grounding to minimize EMI.
Check wiring and power supply regularly to maintain stable signals.
2.5 Maintenance and Calibration
Replace aging sensors promptly to ensure long-term reliability.
Perform regular calibration with reference standards to maintain measurement accuracy.
3. Conclusion
Level gauge reading fluctuations are influenced by multiple factors, including liquid properties, flow conditions, installation environment, electrical interference, and instrument reliability. By applying targeted measures—such as controlling liquid conditions, optimizing installation, reducing EMI, and ensuring routine calibration—industries can significantly improve level measurement stability, reduce maintenance costs, and enhance safety in production.