Water ingression

Bill Becker, STLE - CLS, Global Marketing Communications Advisor, ExxonMobil Fuels & Lubricants

Water and oil don’t mix – well, at least most of the time.

If you operate systems that routinely demonstrate high levels of water ingression, such as central oil systems at paper mills and steel mills or in pulper/re-pulper gearboxes, it is important to try and find the root cause of ingress.

Ingression generally occurs around seals and breathers. If you suspect a shaft seal is the source of ingress, try attaching a slinger ring to the shaft to prevent further ingress. Alternatively, if you suspect a breather is the source, configure a shield to cover the breather and protect from direct water ingress.

You should routinely check high water potential systems for water ingress. Here are just a few, quick steps to help keep your system operational and extend the interval between outages:

1. Open the bottom valve to check for free water (water not mixed with oil), taking care to not open the valve too far, as some systems will automatically shut off. Remember, oil floats in water, so you will see a clear stream of free water, as in the image to the left.

2. As the water level in your system lowers, you will begin to see an oil and water mixture known as an emulsion in place of free water. Emulsion, or “the mayonnaise layer,” looks cloudy and milky, especially in well-agitated systems, such as gear boxes and some central reservoirs.

To the right, see an example of oil and water emulsion – “mayonnaise layer”– draining from the bottom valve.

3. Let the emulsion drain for a few minutes, while keeping a keen eye on the oil level in equipment. During this process, the emulsion of oil and water should turn to clear and bright lubricant oil.

4. If the oil coming out of the bottom valve remains cloudy, employ the added help of a vacuum dehydrator, centrifuge or other water-removal device to eliminate water from the oil.

5. Finally, take an oil sample from similar systems. Compare the samples to identify which systems have oil that looks clear and which samples clearly have water ingression. If you take a sample and it looks cloudy (see below), don’t bother sending it to an oil analysis laboratory; you already know you have water in the system! Save time and fix the water ingression issue, and then remove the water from your system by draining free water and removing remaining water through supplemental filtration.

Cloudy oil samples, such as those on the left, suggest water ingression in the system.