Year of publication: 2007

A powerful particle counter is used in the OELCHECK laboratory. For hydraulic, turbine, circulating and gear oils, it can be used to determine the cleanliness classes according to both ISO 4406 (International Standard Organization) and NAS 1638 (National Aerospace Standard) and the corresponding particle count per particle size. The new particle counter from PAMAS uses a laser sensor to determine the number and size of particles per 100 ml of liquid. With the fully automatic sample changer, up to 500 samples can be processed daily.

Before the measurement, a scanner reads the lab number from the sample bottle and stores it in the database. Then the autosampler transports the sample into a measuring chamber. Here, a stirrer and stainless steel tube are immersed in the liquid. The sample is slowly homogenized without creating air bubbles. It is then pumped through the laser sensor. First, the entire system is flushed with a small amount of sample. Then, depending on the oil viscosity and the dispersion of the individual determinations, up to six individual measurements are made. A computer determines the average values and, depending on these, the cleanliness classes.

The sample vessel is then transported out of the measuring chamber by the conveyor belt and the pump and measuring system are automatically cleaned with solvent.

Immediately after the measurement, the OELCHECK tribologists have the determined measured values available for evaluation via the in-house network.

With one measurement, the instrument calculates both particle counts and cleanliness classes according to ISO 4406 and NAS 1638. In addition, the new particle counter can also measure particle counts and cleanliness classes according to the new ISO 4406. However, when counting according to the new ISO 4406, the NAS values and classes can no longer be determined simultaneously due to the different calibration liquid.