Servo Level Measurement

Servo level measurement is a high-precision tank gauging method that positions a small displacer in the liquid using a servo motor and measuring wire. As the displacer contacts the liquid surface, buoyancy reduces its apparent weight, and the system detects the corresponding torque change to determine level with very high resolution. The same principle supports interface and density measurement in appropriate services.

The method is associated with custody transfer and inventory management because it can deliver exceptional accuracy and repeatability while remaining largely independent of conductivity and dielectric constant. It supports tight loss control, reconciliation, and commercial measurement requirements, making it a cornerstone technology in terminals and tank farms where measurement uncertainty has direct financial impact.

Successful implementation depends on mechanical and process stability. Considerations include stilling well use, turbulence management, product cleanliness, wax or sludge behavior, and maintenance access for moving components. Calibration practices, approvals strategy, and system architecture (redundant gauging, averaging, temperature integration) are often addressed at the tank gauging system level rather than as a standalone instrument decision.

Typical applications include crude oil and refined products (gasoline, diesel), petrochemicals, and specialty chemicals requiring high-accuracy custody transfer measurement and audited inventory reporting. Interface measurement is also used where water bottoms must be tracked precisely to protect product quality and downstream handling.

Servo gauges integrate into inventory platforms and custody transfer systems with defined communications, diagnostic reporting, and verification workflows. When high accuracy and traceable measurement performance are the driving requirements, servo technology provides a mature and widely accepted approach to precision tank gauging.

Field Instruments & Controls, Inc. an exclusive authorized representative of sales and service for Endress+Hauser.