The Visatron VN116/87 Plus is more sensitive compared to the Visatron VN115/87, due to the differential alarm level. The Visatron VN116/87 Plus compares the oil mist concentration from each side of the header-suction-tube section, and responds when there is a difference. This is a sure sign for overheating damage in the compartment group with the higher opacity.
The differential alarm level is carried along with regard to its sensitivity relating to the 4-stage adjustment of the alarm level. To measure the opacity differential, the sample flow of both the header-suction-tube sections are fed to the turbidimetric channel one after the other by closing the respective tube sections alternately by means of reed valves. The microprocessor saves both opacity values and executes the opacity comparison. In the base configuration, if the engine is running fine, both the valves are open to monitor all compartments at the same time.
