Why You Should Control Water Contamination

Water contamination is a machine and uptime killer.  Just a small amount of water, even amounts below the point at which the lubricant becomes hazy, can cut the life of your machines by half or more (see figure).  Here’s how:

  • The lubricating oil film is typically less than five microns in thickness.  The viscosity of oil increases as pressure increases in the loaded zone of bearings and gears, which give the lubricant “film strength.”  The viscosity of water remains constant as pressure increases, thus the presence of water weakens the film strengths of water contaminated lubricant, which in turns reduces film thickness and increases the likelihood of contact, wear and seizure.
  • Water reacts with metals, like iron and copper, in the machine to form chemically reactive byproducts, called “free radicals” that attack the oil and promote rapid oxidation and degradation of the lubricating properties.
  • Water reacts with some additives in your oil to produce corrosive acids.  For example, if water attacks common anti-wear additives, the sulfur component can be converted to hydrogen sulfide and sulfuric acid.
  • Water contamination decreases the surface tension of the oil, increasing the risk of foaming and aeration.

What You Need to Do About Water Contamination

  • Set water contamination control targets – It costs money to control water contamination.  You need targets that are appropriate to the machine type, production criticality and cost to control.
  • Keep it out – The best defense is a good offense.  Controlling the water contamination levels in new oil, high quality vent breathers and high performance seals will usually do the trick.
  • Get it out – What you can’t exclude you must remove.  There are a variety of decontamination devices and technologies to suit different applications.
  • Confirm control – A control system requires a feedback loop.  Onsite or laboratory oil analysis, that includes water contamination testing with the appropriate level of precision.

Things You Need to Control Water Contamination