BW 25

Displacer level transmitter for heavy-duty level and interface applications

  • Continuous measurement of level, liquid-liquid interface or density at extreme process conditions
  • Measuring range: 0.3…5.5 / 1…18 ft
  • Density: ≥0.45 kg/l /≥28.1 lb/ft3
  • -40…+400°C / +752°F; -1…400 barg / -14.5…5801 psig

BW 25 – Version with aluminium housing

BW 25 Displacer level transmitter – Version with aluminium housing

The BW 25 is a loop-powered displacer level transmitter for measuring and/or detecting liquid level or liquid-liquid interface under extreme process conditions. It can deal with corrosive media, high temperatures (up to +400°C / +752°F) and high pressures (up to 400 barg / 5801 psig).

The BW 25 can be used as level indicator without the need of auxiliary power supply. Equipped with a switch module the unit can be used as level switch. With a transmitter module, the unit will function as level transmitter. The three function modes can be combined. Retrofitting the device for receiving add-on functionality is possible without interrupting the process. The BW 25 can also be installed in a bypass chamber, e.g. for applications with agitators.

Product highlights

  • Transmitter, level switch and indicator in one device
  • Easy adjustable level switch with max. 2 set points
  • Can be used as mechanical indicator without auxiliary power supply
  • Modular design for retrofitting under process conditions
  • Welded process seal with external mount housing

Typical applications

  • Tanks with hydrocarbons, solvents, bases at extreme process conditions
  • Interface measurement with large emulsion layers
  • Bypass chamber for applications with agitators
  • Applications in non-hazardous and hazardous areas

Product variants

BM 26A 5000 BW 25

BW 25 with BM26A-5000

Displacer level transmitter with bypass chamber

    • All-in-one solution with displacer level transmitter and bypass chamber
    • Large choice of bypass chamber materials e.g. 316L, 304L, alloy C276, alloy 625
    • Level or interface indication up to 5.5 m / 18 ft
    • Ideal for difficult process conditions, e.g. turbulence, foam


Technical data

Measurement principlesDisplacer
Level measurement typeContinuous measurement
Measured mediaLiquid/liquid interface, Liquids
Contact to measured mediumYes
Interface measurementYes
Displacement rod length0.3…6 m/
1…20 ft
Measuring range (liquids)0.3…5.5 m/
1…18 ft
Process pressure (relative)-1…400 barg/
-14.5…5801 psig
Wetted partsAustenitic stainless steel (1.4404/316L)
Process sealsEthylene propylene diene monomer (EPDM), Fluorocarbon-based synthetic rubber (FKM/FPM), Kalrez® 6375
Accuracy (full scale)+1.5%


Certificates/Approvals ExATEX, EAC Ex
Certificates/Approvals OthersNACE
Ingress protectionIP67, NEMA4X


Digital outputsHART®
Discrete outputsLimit switches
Analogue outputs4…20 mA

Process connections

Flange connectionsEN (1092-1): DN50…100
ASME (B 16.5): 2…4"

Related products

SU 600

Digital panel indicator for level transmitters

  • Digital indication and power supply for 4…20 mA/HART® level transmitters
  • With 2 integrated relays for pump control or other actuators
  • Wide-range power supply unit with 20…253 V AC/DC
  • Carrier rail, panel or wall mounting

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