New technology enhances assessment
Whether your car has an “idiot light” or a real temperature gauge, its designers deemed the engine’s water temperature important enough to monitor it continuously. After all, it wouldn’t do much good to have your engine’s water temperature checked only when you stop for gas. It’s much more likely that a problem will occur while you are on the road rather than when you are at the gas station.
Monitoring contamination of hydraulic fluid would at first seem to be much less critical than engine water temperature. After all, fluid usually becomes contaminated gradually, so monitoring its condition frequently enough can identify problems before they cause any real harm. Engine temperature, however, can increase quickly once a problem occurs. If a hose ruptures, the water pump gives out, or the radiator leaks, the engine can quickly overheat.
Contamination, under certain conditions, also can act quickly to cause catastrophic failure in a hydraulic system. For example, if a pump ingests enough air to cause serious cavitation, it can become inoperative within days. Or if a large quantity of water flows through a system, hydraulic fluid can lose its lubricity, which will result in rapid wear of components. If either of these events occurred a few weeks before a scheduled fluid analysis, the machine could undergo costly downtime.
Granted, these types of problems happen rarely. But if the equipment costs millions of dollars or works in an operation where downtime is measured in thousands of dollars per hour, it becomes practical to continuously monitor fluid cleanliness. Companies, then, are developing systems to monitor the cleanliness of hydraulic fluid continuously while a system is running.
One such prototype system routes pressurized fluid from the pump into a tube through which light is transmitted. When the fluid is clean and relatively free of air and water, a receptor detects the amount and pattern of light transmitted through the fluid.
As the fluid becomes more contaminated, the amount and diffraction of light transmitted through the tube changes. If undissolved water or air is present, the transmitted light becomes more scattered. Calibrating the receptor to these different conditions provides an instantaneous indication of the fluid’s condition. Therefore, appropriate and immediate action can prevent a potentially catastrophic failure.
Another emerging technology enables users to go beyond particle counting and actually analyze wear debris. The system consists of hardware to generate digital photomicrographs and software to aid in analyzing the digital images. Once imported to a PC, images can be compared to those in an atlas of known wear debris using wear debris analysis software. The software also aids in characterizing descriptions, managing data, and generating reports. The analysis can be incorporated into maintenance and statistical process control software used for plant operation and quality assessment.