Solving problems before they happen

Over 85% of all hydraulic system failures are a direct result of contamination. Contamination interferes with the four basic functions of hydraulic fluids: to act as an energy transmission medium; to lubricate internal moving parts; to act as a heat transfer medium; and to seal clearances between moving parts. If any one of these functions is impaired, the hydraulic system will not perform as designed. The resulting downtime can easily cost thousands of pounds per hour. Hydraulic fluid maintenance helps prevent or reduce unplanned downtime. Properly sized, installed, and maintained hydraulic filtration plays a key role in machine preventative maintenance planning. It is important to remember that while the function of a filter may be to clean oil, its purpose is to reduce operating costs. Detecting the level of system cleanliness allows users to prevent impending failure. Matt Fielder, industrial business development manager of Parker Hannifin's Hydraulic Filter Division Europe explains the importance of good filtration and condition monitoring. "Filtration is security," he states. "If you don't put filtration on your systems they won't last as long. Filters are there to add a level of security and system life extension. In my experience, people think a filter is a filter, but there is a lot more to it than that." Keeping hydraulic fluid clean needs filters, but to do it properly you need condition monitoring. "We are the leading manufacturer of field-use portable particle counters for hydraulic fluid condition monitoring," says Fielder. "They are light-obscuration devices which measure particles in fluid down to 4 micron(c). Ongoing condition monitoring ensures that any maintenance programme is enhanced by providing preventative maintenance rather than reactive maintenance." In the wind energy business, where turbines often have to operate in extreme conditions, performance is all important. As turbines have become more efficient, their performance tolerances have increased, making them more complex with more precise controls and higher pressures in the servo and solenoid control valves. As the systems get more complex they have far less tolerance of dirt, so the efficiency of filtration has to improve. "Fifteen years ago a particle removal beta ratio of 75 was the norm, but this is now increased to as much as 1,000," says Fielder. "We are looking to take out more and more of the smaller particles with a much more efficient filter with a longer life dirt-holding capacity. System cleanliness and integrity is of paramount importance, especially when turbines are offshore. The cost of replacing a faulty hydraulic system on an offshore turbine could be ten times that of an onshore one. Accurate real-time condition monitoring will allow you to see a failure days and sometimes weeks prior to it happening." Higher hydraulic pressures, ie 400-600 bar, mean the systems can become more compact; the trade-off is in much tighter tolerances and more fragile of systems. Filtration and condition monitoring play a crucial role in keeping systems running in extreme conditions like those found offshore or in mines. According to Fielder, Parker is now heading towards permanently fixed online particle counting. "This means having a real time monitoring system checking the condition of the oil from second-to-second and reporting it through telemetry. At the moment we look at the water content along with the amount of solids, but we're looking to develop viscosity, density, dielectric and other oil property analysis tools which will give you a really accurate oil life monitoring system," he says.