Clogging indicators for optical, electrical and optical-electrical monitoring of the clogging level of the filter element based on the differential pressure between the dirty side and clean side on the filter element of pressure filters. STAUFF clogging indicators use the special geometry of the control piston to suppress error messages during pressure spikes. Versions with thermostop prevent malfunctions during the cold start phase by suppressing the output signal until a medium temperature of at least 20 °C has been reached.
