GUIDE TECHNIQUE

Water in Hydraulic Oil: Sampling, Diagnosis and Removal Options

Distinguish free and dissolved water in hydraulic oil, investigate the source and choose a suitable removal method.

Water in Hydraulic Oil: Sampling, Diagnosis and Removal Options
Distinguish free and dissolved water in hydraulic oil, investigate the source and choose a suitable removal method.

Water may enter a hydraulic system through condensation, a damaged cooler or maintenance work. It can promote corrosion and change fluid behavior, yet an oil sample that looks clear can still contain dissolved water. The response should begin with measurement and source control.

Separate evidence from appearance

Record where and when the sample was taken, the operating temperature and whether the machine had recently been stopped. HYDAC lists Karl Fischer analysis as a way to determine water content; online water sensors often report relative saturation rather than a direct mass concentration. Those results answer different questions. A cloudy sample may indicate free or emulsified water, but visual clarity alone is not an acceptance test.

Contrôles techniques

  • Compare the result with the fluid and component suppliers’ limits.
  • Inspect breathers, cooler interfaces, washdown routes and tank seals.
  • Check whether the fluid is compatible with the proposed treatment.
  • Trend water readings with temperature and operating state.
  • Review corrosion or filter changes that may indicate a longer problem.

Une erreur courante à éviter

Removing water once without fixing the entry path allows the problem to return. A fine particle filter alone may not remove dissolved water; choose equipment according to the water state and required final condition.

Informations à fournir lors d'une demande de renseignements

  • Fluid identity, volume and latest laboratory results.
  • Sampling location and temperature.
  • Known water-ingress events or cooler leaks.
  • Target condition and available downtime.

Confirm the achieved oil condition with a follow-up sample, then monitor it through representative operation. For related selection guidance, see our oil cleanliness and filtration guide.

Références techniques : HYDAC contamination guide; HYDAC oil dehydration systems. Couverture : schéma conceptuel original, et non une photo du produit.

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