Vibrating level switches: Level control instruments for bulk solids

Since many years already PTL Hermann is specialized in the development and production of vibrating level switches for bulk solids. These products are used for detecting the presence or absence of powdered or granular material that is stored in all kinds of silos, hoppers and containers. Special models for interface detection are available, e.g. to detect sand that has settled in water.

The unique, patented single rod designs of our instruments make them work perfectly and reliably even at critical applications where  conventional products cause problems due to bridge building, material build-up or rat holing.

Product Overview


Vibrating level switch for all kinds of powdered and granular solids. Applicable for heavy materials like cement as well as for light materials with densities down to 20 grams/litre. Grain size from powder to max. 40mm.


Vibrating level switch for all kinds of powdered and granular solids. For heavy materials as well as for extremly light materials like styrofoam with densities even down to 10 grams/litre. Grain size from powder to max. 20mm.


Low-Cost vibrating level switches for grained and granular solids with minimum densities of 20 grams/litre (CV660: 50 grams/litre) and max. grain sizes of 10mm


Vibrating level switch for powdered and granular solids with high process temperatures up to 250°C

Principle of Operation

A mechanical vibrating system gets forced to vibrate on its resonance frequency by means of piezo electric crystals. When the vibrating blade
gets covered by the material to be detected the vibration stops. This is sensed by an electronic circuit which forces a binary output to switch. When the blade gets uncovered the vibration restarts and the output switches back.


The vibration technique has got many advantages over alternative level sensing technologies.

  • unaffected by environmental changes e.g. temperature, pressure, humidity
  • unaffected by material changes
  • unaffected by dust clouds and agitation
  • maximum versatility
  • no calibration required
  • no maintenance required: the vibration has a self cleaning effect
  • highest performance and durability: no moving parts, no wear-out

Furthermore the PTL products offer the following advantages

  • highest sensitivity: even extremely light materials like styrofoam with densities down to 10 grams per litre and lower can be detected
  • the unique, patented single rod designs with its specifically shaped vibrating blades prevent false signalling caused by material build-up, bridging and rat-holing.