Solid Level Switch - Vibrosonde

Vibrosonde is a vibrating rod level switch which is a compact level limit switch for free-flowing solids as well as for bulk solids. It is also available in flameproof enclosure suitable for hazardous areas.

Vibrosonde vibrating rod level switch consists of a cylindrically shaped coaxial resonator which iskept vibrating at its natural frequency by piezo­electric elements. When one of the vibrating elements is covered by the material, the mechanical vibrations are damped. This damping is electrically sensed and the signal is used to cause a relay to change state. The base of the Vibrosonde is relatively insensitive as compared to the tip, so moderate amount of material buildup from vessel wall to base doesn’t affect its operation.

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A vibrating rod is kept in mechanical vibrations at its resonance frequency by piezo-electric crystals. When the service material covers the rod probe, vibrations are damped which is sense electronically and processed signal is used for switching.

  • Low power consumption, less heat, durability
  • Fast switching
  • Self-diagnosis
  • Independent of material’s electrical properties
  • Universal Power Supply: 19-265 V AC & 11-55 V DC
  • Suitable for High temperatures up to:
    • H1: 150°C
    • H2: 200°C
  • Immunity to spurious external vibrations
Mechanical Specifications

 Resonant Frequency

  • ____ Hz to ___ Hz

Probe Length

  • Extensible probe lengths from 250mm up to 3 meters


  • W: Weatherproof
  • P5: IP-65 Weatherproof Housing
  • FA: Flameproof for Gas Group IIa and IIb
  • FC: Flameproof for Gas Group IIc

Process connections (Mounting Arrangement)

  • Threaded Mounting: 1-1/2” BSP, 2” BSP / NPT
  • Flange Mounting: As per specification

Extension Length

  • Pipe GI / SS: 250mm to 3 meters

Probe Length

  • Extension Length + Rod Length

Wetted Parts and Mounting Material

  • S4: SS – 304
  • S6: SS – 316

Process Temperature

  • A (Ambient): below 100°C
  • H (High temperature): up to 150°C
Electrical Specifications

Input power supply & Outputs

  • D: Universal Power Supply 18-55 V DC, 90-265 V AC, Single-point two potential free relay outputs rated at 6A
  • S: Universal Universal Power Supply 18-55 V DC, 90-265 V AC
    • Singe-point – Single relay(Rated 6A)
    • Open-collector PNP output, max 100mA non-inductive load
  • M: 24VDC – 8/16 mA 2-wire Loop powered current output
  • N: 8.2V Namur type current output (ION = 2.2 … 2.5 mA, IOFF = 0.8 … 1.0 mA)

Namur compliance can be attained with a Namur certified isolator.

Power Consumption

  • Less than 3 VA

Fail-safe settings

  • Field selectable (through toggle switches)
  • Open: Fail-safe High, Close: Fail-safe Low

Response Time

  • 1 sec: When covered
  • 2-3 sec: When uncovered

Time Delay Settings

  • Cover and Uncover delay: 1s/3s to 20s, through toggle switches

Sensitivity Settings

  • Field selectable : Through toggle switches
Applications Specifications

 For all Industries requiring level limit detection in Free Flowing solids including:

  • Powders, sand, sugar
  • Pulverized coal
  • Food grains
  • Cement
  • Granular material
  • Flameproof Housing IIa / IIb / IIc certified by CMRI, Dhanbad
  • Flameproof Housing IIc certified by CMRI, Dhanbad
  • IP-68 from ETDC Indore
  • ISI mark from the Bureau of Indian Standards
Switching Indication
  • 2 LED’s
  • Red: Alarm, Green: Normal