LNG tank gauging systems commonly utilize displacement measurement principles to ensure accurate monitoring of the liquid level and inventory in storage tanks. This method is particularly effective in the challenging environment of LNG storage, where extreme cold temperatures and dynamic conditions are present.
Principle of Displacement Measurement in LNG Tank Gauging
Displacement measurement involves detecting the position or movement of a probe, float, or mechanical element that responds to changes in the liquid level. This method is widely used in systems like servo gauges for precise LNG level monitoring.
How Servo Tank Gauges Work (Common Displacement Method)
-
Suspended Displacer:
A small displacer (float) is suspended inside the tank using a measuring wire connected to a servo motor.
-
Equilibrium Mechanism:
The servo motor continuously adjusts to keep the displacer at the interface between the liquid and vapor phases.
-
Force Detection:
The LNG tank gauging system measures the force required to maintain this balance, which directly correlates to the liquid level.
-
Density Measurement:
Advanced servo gauges can also determine liquid density by analyzing the buoyancy force acting on the displacer.
Key Advantages of Displacement-Based Gauging in LNG Tanks
✅ High Accuracy — Servo gauges offer precision within ±1mm, ideal for managing valuable LNG inventory.
✅ Density Profiling — Helps detect stratification in LNG, improving safety and efficiency.
✅ Reliable in Cryogenic Conditions — Displacement methods are well-suited for LNG’s extremely low temperatures.
✅ Continuous Monitoring — Provides real-time data for accurate inventory control.
Displacement-based LNG tank gauging systems are highly trusted in industries where precision and safety are paramount, especially in large-scale LNG storage facilities.