Even before being put into use, oils are at risk of water contamination during transportation and storage. When upright containers (particularly drums) are stored outside or during loading, water can collect on top of the container. As ambient temperatures rise and fall, moisture can be drawn into the barrel via the barrel caps.
During operation water can get into the oil through openings on the tank, as condensation from the air or through worn cylinders and seals. Condensation is the most common cause of water contamination in oil during operation.
Especially in the case of mobile machinery operating outdoors water vapour can condense in the tank every time the system cools down. If equipment is relatively static this often leads to rust and other corrosion problems, especially above the oil level. As soon as there is a higher amount of water in the oil, microorganisms begin to grow. The result is the accumulation of sludge and a change in viscosity. The first signs of a problem are an unpleasant smell and a change in colour (clouding of the oil).
|Fluid type||new oil value (harmless)||max. tolerable value (according to known norms)||filtration recommended|
|HLP, HVLP||100 - 400 ppm||500 ppm||> 400 ppm|
|HEES, HETG, HEPR||400 - 700 ppm||1.000 ppm||> 900 ppm|