Bühler Technologies GmbH

Filter Monitoring

Filter Monitoring

Traditionally, return or line filters are monitored by so-called contamination indicators in stationary hydraulics and in lubrication systems. In most applications, this takes place by means of mechanical/electrical devices, which create a visual as well as an electrical signal. The increasing pressure drop through the filter elements resulting from the accumulation of particles is used to generate the signals.

In tank top return filters, this leads to a dynamic pressure in the filter housing and to a differential pressure between input and output side in line filters. However, since the viscosity of the oil changes along with the operating temperature, the pressure drop can also be caused by colder oil. This often leads to filter elements being replaced long before their dirt holding capacity has been reached.

This so-called cold start effect has increasing influence on partially loaded filter elements. In addition to this negative effect there is also the disadvantage that only one signal is given. This frequently leads to a maintenance process in the middle of the work shift, almost always in connection with machine downtime. The Bühler VSA prevent the cold start effect and categorically generate two signal points. These alarms are reported visually as well as electrically at approx. 75% and 100% of the filter capacity to ensure a more economical use of the filter elements and enable planning maintenance work.


  • [Translate to English:]
    Contamination indicator BCI 24-Dx
    • Continuous pressure drop measurement
    • 2 fixed switching outputs for 75 % and 100 % contamination level
    • 4-20 mA output for pressure drop (version 2S1A only)
    • Signal suppression for outputs during the cold start phase and temporary pressure peaks (version 2S1A only)
    • IO-Link version with 1 x programmable switching outputConnecting flange compatible with third-party products G1/2 Hydac, G1/2 Stauff, M20x1.5 Filtration Group, M20x1.5 Bosch Rexroth or G1/2 MP-Filtri
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  • Product Archive
    • [Translate to English:] Prozessor gesteuerter Differenz-Druck-Sensor zur Überwachung von Filter-Zustand
      Differential pressure sensor VSA 24-D
      • two switching outputs
      • signal suppression during the cold start phase and for short-term pressure peaks
      • visual / electrical display of status and error messages
      • self-monitoring
      • LED illuminated halo visible from every angle
      • display of status and error messages
      • M12 connector
      • reset function
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    • [Translate to English:] Prozessor-gesteuerter Stau-Druck-Schalter und Temperatur-Sensor
      Back pressure sensor VSA 24-S
      • two switching outputs
      • signal suppression during the cold start phase and for short-term pressure peaks
      • visual / electrical display of status and error messages
      • self-monitoring
      • reset function
      • LED illuminated halo visible from every angle
      Show details