The saturation level is the amount of water that can dissolve in the oil's molecular chemistry and is typically 200 - 300 ppm at 68°F (20°C) for mineral hydraulic oil. For instance, highly refined mineral oils with few additives hold little water before becoming saturated, about 100 parts per million (ppm) at 70°F. The physical properties most affected by the presence of water include: The chemical properties on which even small amounts of water can have a measurable effect are: Table 1. Mass transfer purifiers are recommended due to their minimal impact on fluid chemical and physical properties. Relative content expressed as percent of saturation indicates the fluid water content relative to its saturation level at a given temperature. For most industrial hydraulic and lubrication systems, a properly set control level, typically recommended at 50 percent saturation or less, minimizes the detrimental effects of water contamination. Surface corrosion, probably the most obvious effect, is directly linked to the presence of free bulk water. It gives a clearer warning of impending formation of free water. An integral part of effective water control is the ability to efficiently remove water from the hydraulic or lubrication system. These breathers combine a woven-polyester media that filters particles as small as 3 microns, with silica gel desiccant to remove water vapor from incoming air. ), caused by the presence of water, which can lead to increased component wear2, and jamming of components due to ice crystals formed at low temperatures. Shade, CFPS The service requires full JavaScript support in order to view this website. While both processes utilize the concentration gradient between the fluid and the evacuated air to evaporate the water from the fluid, the flash distillation technology also applies heat to further boil off more water and operates at a higher vacuum. The saturation level is the amount of water that can dissolve in the oil's molecular chemistry and is typically 200 - 300 ppm at 68°F (20°C) for mineral hydraulic oil. The vacuum in the vessel is about 20 percent atmospheric pressure and the air expands to about five times its original volume. Yes, water contamination can be problematic, but how can water be measured? Centrifugal separation is suited for continuous decontamination of fluids, but requires excellent water demulsibility (oil/water separation). You will be redirected once the validation is complete. The Karl Fischer method is used for the determination of the absolute water content in fluids as the reference for this conversion.4 This conversion requires the measurement of the fluid temperature at the water sensor, which is achieved with an integral resistance temperature detector (RTD) sensor. "The Effect of Water in Lubricating Oil on Bearing Fatigue Life." The first state, known as dissolved water, is characterized by individual water molecules dispersed throughout the oil. Two technologies are available, flash distillation vacuum dehydration and mass transfer vacuum dehydration. Water is a significant contaminant in hydraulic and lubrication fluid systems, resulting in degradation of system components and fluid. If load and surface speed remain constant, but elevated operating temperature causes viscosity to fall below that required to maintain a hydrodynamic film, boundary lubrication occurs; this creates creating the possibility of friction and adhesive wear. I recently audited a hydraulic system with cloudy oil that was found to contain greater than 1% (10,000 ppm) water. If you enjoyed this article, you'll love Brendan Casey's Inside Hydraulics newsletter. "Comparison of Water Measurement Results in Polyol Ester-based Lubricant Fluids by the Coulometric Karl Fischer Method and a Thin Film Polymer Capacitive Water Sensor." Accelerated metal surface fatigue, such as in bearings, can be promoted even if all the water present in the fluid is dissolved. The control level should be selected, where possible, at the lowest anticipated system temperature, such as cold ambient during a shutdown. (Vacuum) pressure is the main factor. A saturation curve for a typical turbine lube oil (Figure 1), illustrates the relationship between temperature and saturation levels: If a system operates at 100°F and the fluid contains only dissolved water (100 ppm), then a drop to ambient temperature (70°F), as during a shutdown, would lead to the presence of free water in the system, because the saturation level at ambient conditions is less than 100 ppm. Substantial cost savings can be gained from operating with dry fluids. Project Engineer (Hydraulic Design) Water monitoring techniques must be accurate, repeatable and in real time so that increases in water content can be promptly rectified. If you have worked with hydraulic equipment for any length of time, it's likely that you've come across a hydraulic system with cloudy oil. Farooq and R. Fowler. Jack Bergstrom When combined with a water sensor, mass transfer purifiers can be utilized to control water in hydraulic and lubrication systems continuously; however, not to the low percent saturation levels obtained with purifiers. Capacitive Water Sensor Technology. Methods for Water Removal JOAP International Condition Monitoring Conference, April 3-6, 2000. ?I just love this newsletter. There are a variety of techniques to measure the quantity of water in hydraulic fluids and lubricants. Water can also enter the fluid system from the process side, from leaky heat exchangers or coolers, or direct ingression of process water, such as cooling water, washdown water or steam. Copyright © 2002 - 2013 Brendan Casey; Insider Secrets to Hydraulics. ?The knowledge I've gained from this newsletter has been so valuable it has earned me a raise!? The fluid is fed into the vacuum chamber where it is spread into a thin film to reduce the path length for the water to reach the free surface and so be transferred to the air. Sharpe Equipment Inc. Coalescers separate water droplets from the fluid stream by arresting them on or near the surface of a filter or screen so that the droplets fuse together (coalesce) and grow to a size that allows them to fall to the bottom of the vessel where they can be extracted. For this reason, an oil can contain a significant concentration of dissolved water with n… "Moisture, the Second Most Destructive Lubricant Contaminant and its Effect on Bearing Life. Water can be present in hydraulic fluids and other lubricants as either dissolved, emulsified or free water. Relative content expressed as percent of saturation indicates the fluid water content relative to its saturation level at a given temperature. Listen to what a few of his subscribers have to say: ", M. Weinschelbaum. Because coalescers rely on the interfacial tension between the water and the fluid phase, they tend to become ineffective in the presence of surface-active agents in the fluid. This method is typically used for water content specifications. form - don't forget to capitalize the first letter of your name - and hit 'SUBSCRIBE NOW!'. Water molecules migrate into or out of this layer depending on the humidity of the polymer relative to the fluid. Measuring Water Content in Fluids Heavy Equipment Mechanic The ultimate choice depends upon whether a quick assessment or a precise measurement is required. This can be done in a number of ways. Vacuum distillation - This technique employs a combination of heat and vacuum. www.hydraulicspneumatics.com is using a security service for protection against online attacks. be sold or given away for any reason. But what exactly does that mean? Saturation Curve for a Typical Turbine Lube Oil. The reaction of oxygen with fluid basestock forms oxygenated compounds and is accelerated by heat and the presence of water. The presence of water in hydraulic fluids and lubricants can have wide-ranging effects on system components. This process is automatic. A major point of water ingression is through the reservoir headspace. On the other hand, ingression of water at operating temperature can also lead to the presence of free water, if the saturation level is reached or exceeded (at 100°F, this would be 200 ppm). Coalescers cannot separate dissolved water. Michael S Lawrence This instrument is a development of the air moisture sensor. This however does not account for ingression of water, which is why it is recommended to set the control level to 50 percent saturation, as this provides a safeguard against surface corrosion or loss of fluid characteristics (for example, lubricity, compressibility) due to the presence of free water. Vacuum Dehydration Process Comparison. In the case of small systems with high levels of water contamination, changing the oil may be more cost-effective than using any of the above methods of water removal. There are two methods commonly used to express water content in hydraulic and lubrication fluids: The absolute content in ppm expresses the water content in parts per million (ppm) either by weight or volume. n Figure 5, an aerosol mist is generated by pumping the fluid through spray nozzles. Figure 4 illustrates this methodology. This change in capacitance is then converted into a signal proportional to the saturation level of the fluid, in a percent range of zero to 100, where 100 percent saturation corresponds to the solubility limit of water in the fluid at the given temperature.