How can impurities arise in the thermal oil and which reasons does this have?

Especially in new systems, it often happens that shavings and metal particles of the inner wall of the pipes and the abrasion of pumps and fittings pollute the oil from the beginning. Therefore, it is optimal to filter the thermal oil already from the beginning.

Later – during the running operation of the system – oxidation products occur already from 80 °C and reaction products are generated from 250 °C. These particles (> 40µm), e.g. oil coal or coke, are clearly visible without a microscope as well.

Many of these mentioned particles are too small for the strainers upstream the pumps and control valves.