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.