It’s no secret that water can cause incredible damage to any hydraulic system. If you’ve been a hydraulic system engineer for some time, you may have already seen a system that has cloudy oil in it. Cloudy oil is the result of having so much water in oil that it is above the saturation level. Most often the saturation level will be at 200 to 300 ppm at a temperature of 68°F or 20°C. Going the other way on the scale, by reducing water in a system, you can increase the life of it by a significant amount. For example, by ensuring that it’s at a level that is lower than 100 ppm, the life of a bearing could be increased by 150%. (According to Timken Bearing Company in their Stauff Contamination Control Program). If oil is cloudy, then it will have at least 200 ppm of water in it. Of course, the greater the level of water in the oil, the more issues you’ll have in terms of performance and reliability. We once had a look at a system for a client and it had more than 10,000 ppm of water which is more than 1%. Here’s a checklist of why you don’t want water in your hydraulic fluid: · It decreases the presence of some additives · It reacts with some additives to make corrosive products that will attack metals · Clogs filters · Increases cavitation · Increases air entrapment · Reduces lubrication Although if you do your own research, you may come across information that states that having 0.1% of water in your system is perfectly acceptable, according to the Timken Bearing Company report, it is far better to have as little as 0.01% of water in your hydraulic fluid as it will increase life expectancy of bearings in their case, but components etc. in ours. If that isn’t enough information to convince you, then take note that 500 ppm of water and over can even create micro-biological contamination if you have the following elements also present: · Food: i.e. nitrogen, carbon or phosphorous from the oil · Oxygen: there is usually between 7 and 10% of air in hydraulic oil · Temperature: bacterial growth can occur between 24°C and 49°C · Low flow: the reservoir is a great place for breeding to take place · Particles: these will help to transport and colonizing Although you will need each of the above present to help keep bacterial growth going, water is what is behind the success of it. Therefore, keeping your oil dry is critical in stopping growth.