Endress+Hauser Proservo NMS81 is an intelligent servo tank gauging instrument developed for high-accuracy liquid level measurement, inventory management and custody transfer applications.

The instrument uses a servo-controlled displacer suspended from a precision measuring wire. Changes in buoyancy are detected and used to determine the liquid surface position.

Depending on the selected configuration, the NMS81 can also perform interface measurement, spot density measurement and density profiling.

The instrument is suitable for demanding industrial applications involving crude oil, petroleum products, petrochemicals, chemicals and liquefied gases.

Verified Product-Family Technical Specifications:

• Manufacturer: Endress+Hauser

• Product Model: Proservo NMS81

• Measuring Principle: Servo / Float Tank Gauging

• Measured Variables: Liquid level, interface level, spot density and density profile

• Best Level Measurement Accuracy: ±0.4 mm under specified reference conditions

• Level and Interface Resolution: ≤0.1 mm

• Reference Interface Measurement Error: ±2 mm under specified conditions

• Maximum Measurement Distance: Up to 55 m, depending on configuration

• Process Temperature: −200°C to +200°C

• Maximum Process Pressure: 25 bar absolute

• Standard Ambient Temperature: −40°C to +60°C

• Optional Wetted Materials: 316L, Alloy C276, PTFE

• Optional Process Connections: DN80 / DN100 / DN150 flanges

• Available Power Supply Ranges: 85–264 VAC, 52–74 VAC or 19–64 VDC

• Optional Communication Protocols: Modbus RS485, V1, WM550 and HART

• Optional I/O: 4–20 mA, relay, RTD and discrete inputs

• Available Product-Family Approvals: ATEX, IECEx, SIL, OIML, NMi, PTB and other regional certifications

Configuration Verification Required:

The exact displacer material, measuring wire length, process flange, power supply, communication interface, I/O configuration and explosion-protection approvals must be confirmed against the manufacturer’s configuration record.

The supplementary identifier NMS81-A5X6/0 has not been independently decoded.

Important: The specifications above describe the verified capabilities and options of the Proservo NMS81 product family. They must not be interpreted as confirmation that every option is included in the specific ordering code.