The purity of the hydraulic media is crucial for the fault-free and low-maintenance operation of hydraulic and lubrication systems. Failure analysis shows that 70 to 80 percent of all machine failures are caused by contamination of the operating fluids due to inadequate oil maintenance. After all, precise hydraulic and lubrication systems work with micrometre gap dimensions with the result that even the smallest particles of dirt can lead to increased energy consumption through friction, reduced performance or often costly downtimes. This frequently results in unplanned oil changes or the replacement of sensitive components. The Stauff LPM-II-plus particle monitor is used in industrial systems with maximum operating pressures of 420 bar in which continuous measurement or analysis of the hydraulic fluids is required. The redesigned particle monitor, which has been adapted to customer requirements, is an automatic optical particle counter with high-performance LEDs, which automatically detect the degree of contamination of hydraulic fluids in the form of an 8-channel measurement. This enables precise determination of the particle sizes in compliance with international standards, including ISO 4406, NAS 1638, AS 4059E and ISO 11218. The status of oil purity is unequivocally displayed by a colour-coded LCD display and using coloured LEDs. Corresponding particle limit values can be individually adapted and set using the software supplied. The LPM-II-plus can be used both as a stand-alone measuring unit with an internal memory for max. 4000 measurements as well as being controlled via two switch outputs on PC and PLC system control or parallel by a remote display unit. The optional USB interface enables the measured data to be transferred directly to a data carrier. The LPM-II-plus now offers a 4-20 mA time-multiplex interface in addition to the Modbus and CAN bus interface to provide analogue measuring signals for analysis as well. Depending on the model, the LPM-II-plus is immediately available with a water-in-oil sensor and temperature sensor, as well as with a connecting cable and the relevant software.