Water contamination in lubricating oil accelerates the natural oxidation that normally takes place in the oil. Even when additives are used to retard the natural process, the presence of water will degrade the effectiveness of certain additives potentially leading to tight emulsions and the formation of sediment in the oil. In addition, water in lubricating oil increases the risk of microbial attack and contributes to further loss of oil performance and thereby to corrosion of the components in the various oil systems.
In modern diesel engines, frictional surfaces are exposed to heavy loads, which place tough demands on lubricant condition and performance. The Gertsen & Olufsen AS Survey Water Monitor (SWM) is a unique system that provides a way to monitor water contamination in real-time, alerting equipment owners to take immediate corrective action, if or when necessary. The system is suitable for use on all types of oil-lubricated machinery, including engines, turbines, gearboxes, compressors and hydraulic systems.
The working principle of the SWM system is based on the difference in boiling points of water and oil. In short, a continuous flow of oil is by-passed through an evaporator where the oil is heated sufficiently to vaporize any water. Subsequently, the water is condensed and measured by passing it through a sealed orifice calibrated to produce drops of a fixed size. Each drop from the orifice causes an electrical impulse, which by way of the relay box is fed to a computer with results displayed locally.
When a fixed water concentration limit (decided by the operator or engine manufacturer) is breached, an alarm will sound.
The measured value is converted into a current signal, 0 to 20 mA or 4 to 20 mA, representing 0 percent to 5 percent water content. The SWM system is recommended for installation on new engines and as a valuable safety add-on for existing engines and various oil systems.
The newest version of the instrument provides a water content measurement as low as 0.03 percent (lower limit of sensitivity), which represents literally one single drop of water in a measured volume of oil. The SWM constantly updates the readings, giving a real-time characterization of the oil’s moisture level.
In the past, the unit was used primarily on four-stroke fast- running engines, including engines of some of the biggest cruise ships in the world. In addition, a number of SWM systems have been supplied to international ship owners of large tankers and container vessels. However, these systems are now being used to monitor the separators on two-stroke engines as a redundant safety measure, ensuring that the lubricating oil is free of significant water content at all times.
Although the SWM was initially intended for use in lubricating oil systems, it has proven that it can be used in a variety of applications, including fuel oil systems and hydraulic oil systems. One of the latest applications is measuring water in oil on thruster oil systems and Azipod systems (podded propulsion units for large marine vessels).