Vibrating Fork Level Switch

The resonator utilizes a piezoelectric driven tuning fork that exhibits a large change in resonant frequency when immersed in any liquid. A "smart" microprocessor-based electronic unit keeps the sensor in a resonant state as it changes from dry to wet or wet to dry.



The resonant frequency is continuously monitored for changes created by a wet or dry sensor and an alarm is provided via relay. The RS85 should be used when the application requires optional process connections, exotic materials of construction, coatings, finishes or adjustable time delay and density set point.



  • Direct Replacement for Ultrasonic Gap Switches, RF Capacitance Switches, Float Switches and Other Technologies
  • Immune to Coating or Build-Up on Sensor
  • Robust Sensing Element
  • ¾” and 1” (NPT, BSPT) Process Connections
  • Choice of International Flanges and Range of Tri-Clamp Fittings and Probe Finishes
    • Temperatures between -40oF to 350oF (-40oC to 177oC) with HT6 High Temp Ext.
    • Pressures to 2000 psig (138 bar)
    • Viscosity up to 20000 cP
    • Density from 0.45 to 2.0
  • Single or Dual Compartment Housing with Viewing Cover
  • Field Selectable Parameters with External Magnet or Internal Pushbuttons (Fail Safe, Density, Time Delay)
  • Modular Electronics with Alarm Status LED
  • Self-Test Diagnostics
  • Extended Probe Lengths to 120 in (3048 mm)


  • Hermetic Seal Probe and Housing
  • Special Alloy Sensors (Hastelloy) and Halar/PFA Coating for Chemical Resistance
  • Remote Mount Electronics
  • Low / High Pressure Packing Glands


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