Measurement and control of a servo tank gauge (STG) is essential for accurate and reliable monitoring of liquid levels in storage tanks. Servo tank gauges are commonly used in various industries, such as oil and gas, petrochemicals, and water treatment, to measure tank levels and provide real-time data for inventory management and process control. The measurement and control process typically involves the following steps:
- Level Measurement: The servo tank gauge uses a servo motor and a displacer or probe immersed in the liquid to measure the tank’s level. The servo motor moves the displacer up and down based on the liquid level changes. The displacer’s position is then converted into an electrical signal, representing the tank level.
- Sensor Calibration: Before installation and operation, the servo tank gauge needs to be calibrated to ensure accurate level measurements. Calibration involves setting the zero level (empty tank) and the span (full tank) for the gauge. This process ensures that the electrical signal output corresponds accurately to the tank’s actual liquid level.
- Data Processing: The electrical signal from the servo tank gauge is sent to a data processing unit, which may be a local display or a remote monitoring system. The data processing unit converts the electrical signal into meaningful level measurements and displays them in the desired units (e.g., volume, percentage, or depth).
- Tank Level Display: The measured tank level is displayed on the local display or transmitted to a central control room or monitoring station for remote visualization. Modern servo tank gauges may have digital displays with intuitive interfaces, making it easy for operators to read and interpret the tank level information.
- Alarm and Control Functions: Servo tank gauges can be equipped with alarm and control functions to alert operators when the tank level reaches critical thresholds. For example, if the tank level exceeds a high or low limit, an alarm can be triggered to prompt immediate action. Additionally, the gauge may have control outputs to automate processes, such as starting or stopping liquid transfer when certain levels are reached.
- Data Logging and Integration: Many servo tank gauges are designed to log and store historical data, allowing for trend analysis and performance evaluation. The data can also be integrated into supervisory control and data acquisition (SCADA) systems or other enterprise-level software for broader control and management of multiple tanks.
- Maintenance and Calibration: Regular maintenance and calibration are crucial to ensuring the accuracy and reliability of the servo tank gauge. Periodic checks and adjustments may be required to compensate for any changes in the gauge’s performance over time.
The measurement and control of a servo tank gauge provide valuable information to optimize storage and distribution processes, prevent overfills, and enhance safety in industries that rely on precise liquid level management.