Vibronic Point Level Detection

Vibronic Point Level Detection

Vibronic point level detection is a switching technology for liquids and bulk solids that uses a vibrating element (commonly a tuning fork or single-rod probe). It is frequently chosen for dependable overfill prevention and point control because its switching behavior is largely insensitive to many process disturbances that affect other point level methods. The technology is used broadly across industries for both operational control and protective functions.

The measuring principle excites the sensor at its resonant frequency using a piezoelectric drive. In liquids, immersion changes the oscillation frequency; in solids, immersion typically changes oscillation amplitude. Electronics detect these changes and convert them into a discrete switching signal. The approach supports point detection without requiring calibration to a specific setpoint in the same way many analog methods do.

Benefits include reliable switching in the presence of turbulence, foam, vibration, and build-up, as well as relative immunity to changing media properties within the device’s operating envelope. Many vibronic switches are designed for high availability through self-monitoring and are commonly applied as an independent “second line” for overfill prevention. Because there are no rotating or sliding parts, wear is typically low and maintenance demands are reduced.

Typical applications include minimum/maximum level control in tanks, overfill protection on storage and process vessels, certified leak detection, and point level alarms in pipelines or sumps. In bulk solids, vibronic devices are used for silo high/low indication in fine-grained powders and lumpy solids, including services in chemical and food processes and in hazardous-area solids handling.

Selection should consider the minimum density and viscosity range, coating tendency, and mechanical loads from solids flow or agitation. Installation orientation and fork/rod length should be matched to nozzle geometry and desired switching behavior. When used for safety functions, proof testing strategy, diagnostic coverage expectations, and output fail-safe configuration should be defined as part of the overall protective instrumented function design.

Forberg Smith, an exclusive authorized representative of sales and service for Endress+Hauser.