Watch Out – Foaming in Lubricating Oils!


What is Foaming:


Foaming in oil is mainly due to the accumulation of small air bubbles at the surface of the lubricant.  It is caused by excessive agitation, inadequate levels of lubricating oil, air leaks/ingress, contamination or cavitation.  Foaming is an undesired phenomenon in engines, hydraulics, turbines and cooling systems.  In severe cases, it can even leak through breathers, sight glasses and dipsticks.  Foaming may also lead to misinterpretation of oil levels and subsequent machinery failure.

What Foaming can do to your Machinery?

The Foam acts as a thermal insulator and thus the oil temperature can become difficult to control.  It is a major cause of overheating, loss of pump pressure, loss of power, cavitation, oxidation and failure of hydraulic systems.  It has a direct impact on the lubrication of the engine/hydraulic systems by creating air buffer zones in the circuit, which annihilate the lubricating properties of the oil.

In order to prevent or reduce the formation of foam, lubricants contain anti-foaming additives, mostly silicon-based additives.  Their role is to break the air bubbles.

Fresh New Oil – No Foaming

Oil in Use – Foaming

Why your Lubricating Oil Foam?

There are many reasons for oil to Foam.  They are listed below:

  1. Contamination is a very frequent one. Common contaminants consist of water, solid particles, grease or cross contamination of the oil with another fluid or addition of a wrong lubricant,
  2. Depleted antifoaming additives (possibly due to the use of excessively fine filtration and electrostatic separation technologies)
  3. Mechanical issues causing excessive aeration of the fluid, leaky seals, etc.
  4. Contamination of the lubricant with grease,
  5. Overfilling of the sump with a splash- and bath-lubricated compartments.

Can Lubricant Analysis determine the specific cause of foaming?

Viswa Lab can get the lube oil samples tested in order to determine the exact cause of foaming and recommend corrective actions.  The tests include routine complete lube oil analysis with specific attention to:

  1. Water %,
  2. Particle counting
  3. Patch test and Microscopic examination,
  4. Elemental Analysis, and
  5. Comparison of results with a fresh new oil test result

Actions to Mitigate Foaming:

  1. An oil change, or at least a partial drain and refill,
  2. Depending upon the type of contamination, a system flush might be required,
  3. Make sure you address the root of the problem before conducting the drain and flush,
  4. Troubleshooting foaming can be a challenging process, but by a process of elimination, you should be able to identify and correct the root cause,
  5. Viswa Lab recommends to land a Fresh/New oil sample along with used/contaminated oil sample for testing. The Lab tests Fresh/New oil at no extra charge when sent along with used/contaminated oil for analysis.

Machinery to Look for Foaming:

  1. Purifier Gear Case
  2. Reduction Gears for propeller
  3. Turbine gears and crankcase
  4. Mooring and Anchor gears and Many other specialized machinery depending upon ship type.

Image Credits: Machinery Lubrication, Noria


Comments are closed.