A displacer-type level transmitter BW 25

The BW 25 is a displacer-type level transmitter for continuous measurement of liquid level, interface, or density under extreme and demanding industrial conditions. It is specifically designed for high pressures and temperatures where other level measurement methods are unreliable or impossible.

Key Technical Specifications:

• Measuring range: 0.3…5.5 m

• Minimum liquid density: ≥ 0.45 kg/l

• Process temperature: -40…+400 °C (up to +450 °C depending on version)

• Process pressure: up to 400 bar (depending on material)

Principle of Operation

The BW 25 operates according to Archimedes’ principle (buoyancy force). A displacer of defined volume and weight is immersed in the liquid and suspended by a measuring spring or torque tube. As the liquid level changes, the effective weight of the displacer changes due to the varying buoyancy force. This change in weight is transmitted to a highly precise force transducer. The electronics convert the force signal into a standard 4…20 mA analog signal (with HART) or digital signal proportional to level, interface, or density.

Features

• Measures level, interface, and density with a single device

• High accuracy and repeatability (±0.1 %)

• Materials: stainless steel, Hastelloy, Monel, titanium, Incoloy, PTFE coating, etc.

• Various process connections: flanged (DIN/EN, ANSI), threaded, special high-pressure versions

• Versions with external measuring chamber or direct installation in the vessel

• Ex approvals (ATEX, IECEx, FM, NEPSI, etc.)

• SIL 2/3 certified

• Options: local indicator, heating/insulation jacket, special displacers for aggressive media

Main Application Areas

• Oil & gas production (separators, glycol regenerators)

• Refining and petrochemical industry (distillation columns, reactors)

• Chemical industry (aggressive and viscous media)

• Power generation (boiler drums, feedwater heaters)

• Fertilizer, acid, and alkali production

• Food & pharmaceutical industry (only hygienic versions)

• Any processes involving high pressure/temperature or interface measurement (e.g., water/hydrocarbon)

Advantages of BW 25 Displacer Level Transmitters

• Reliable operation under extreme conditions (high pressure & temperature) where radar, ultrasonic, or capacitive devices fail

• Independent of dielectric constant, conductivity, foam, vapor, or turbulence

• Simultaneous interface and density measurement without additional instruments

• Very high accuracy and long-term stability (virtually no moving parts except the displacer)

• Simple calibration (possible “dry” calibration without filling the vessel)

• Long service life even in aggressive media thanks to proper material selection

• Hot-tap installation possible on operating vessels (with external chamber)