Servo Level Measurement

Servo Level Measurement

Servo Level measurement is a precision tank-gauging method that uses a servo-controlled displacer (or float) suspended on a measuring wire. The instrument maintains the displacer at the liquid surface by balancing buoyancy forces and measures level from the wire position, producing continuous level data tailored to custody transfer and inventory control. The approach is designed for high-accuracy storage applications.

A defining advantage is measurement precision and repeatability over large tank heights, supporting tight inventory reconciliation and transfer accounting. Servo gauging can be engineered to support additional tank measurements - such as water-bottom/interface detection or other gauging functions - depending on configuration and metrology requirements. Long-term stability and proven performance in terminal and tank farm environments make it a common choice where measurement uncertainty has direct commercial impact.

Engineering considerations include the mechanical nature of the displacer and wire system, which benefits from controlled installation conditions and periodic maintenance. Product fouling, heavy waxing, or sticky residues can impact displacer behavior if not addressed via selection and service strategy. Turbulence and surface motion are typically managed with stilling wells or guide arrangements, and hazardous-area compliance is often central in storage installations.

Typical applications include crude and refined product storage tanks, chemical tank farms, terminals, marine and pipeline custody transfer points, and facilities where inventory control is tightly audited. Servo gauging supports automated tank farm operations, loading/unloading sequences, and overfill protection architectures that require dependable reference levels. It is commonly paired with tank inventory systems for volume calculation, mass balance, and reporting.

Integration uses standard instrumentation interfaces and tank-gauging communications to feed inventory and control platforms, often with redundancy and verification features aligned with custody transfer practice. Commissioning emphasizes reference height definition, geometry configuration, and verifying response across the operating range. Diagnostics and planned maintenance intervals help sustain accuracy and availability over long service life.

Miller Mechanical Specialties, an exclusive authorized representative of sales and service for Endress+Hauser.