In principle, the new generation particle counter in the OELCHECK laboratory works like existing devices with a laser sensor, but the samples are now homogenised and prepared better. The entire process has been simplified and optimised. In the conventional particle counting process, air bubbles and water droplets can influence the results. The new device rules out this possibility in the majority of cases.
Particle counting is one of the first stages of analysis an oil sample undergoes. Previous machines analysed the sample directly from the original container. As counting can take up to 5 minutes, this may lead to delays further along the testing process, because too many samples get backed up as they wait to be counted. Now laboratory assistants pour only 20 ml approximately of the homogenised sample into a plastic beaker, which goes into the new counter. Afterwards the sample container is immediately transferred to the next examination stage, which of course reduces processing times. Instead of only 20 samples, the new device can be loaded with 80 sample containers. Before the actual counting, an innovative ultrasound sensor determines the exact size of the sample so that an exact solvent mixture of 75% toluene and 25% propanol at a ratio of 2:1 (based on ASTM D7647-10) can be used and this can be taken into account to determine a blind value. Immediately before the measurement, the sample is homogenised and degassed. Air bubbles escape quickly from the diluted sample and can therefore no longer be counted in the analysis. The effect of the propanol in the solvent mixture is that possible water droplets dissolve and become „invisible“. In addition, the toluene dissolves any soft reaction products which may be present and ensures that only the hard particles which are actually present in the oil are counted.
The entire diluted sample of around 30 ml is then counted three times in a row, from which a mean average is extrapolated. If the individual values differ from each other greatly, the particle counter rejects the whole analysis and requests a new specimen. It doesn‘t get much more precise than that!
A Canadian company is behind our new particle counter. The core of the machine, the particle sensor, comes from Markus Klotz GmbH. In the OELCHECK laboratory, the innovative particle counter has already proven itself to be highly effective. Each day it looks at some 250 samples and is set to be joined by a second device of the same make soon.