Lubricant
Two important ways to help enhance the performance and durability of a company?s hydraulic systems are to use a high performance hydraulic fluid and to institute a proactive maintenance and oil analysis plan, says Rupinder Paintal.

Hydraulic systems are used in nearly all industrial and commercial market sectors such as machine shops, general manufacturing, power plants, construction, forestry and mining, just to name a few. And, compared to their predecessors, today?s hydraulic units are far more sophisticated. The need to improve productivity and lower costs has led to significant changes in hydraulic component technology and system design, creating systems that are more compact, yet more powerful than ever.

In fact, modern hydraulic systems feature reservoirs that are 60 to 80 per cent smaller than those of older systems, operate with sophisticated computer controlled valves and use ever increasing system pressures. These smaller, more power-dense systems have limited residence time to reject contaminants, such as solid particles and air, and operate at higher temperatures, both of which stress the fluid and system components. Precision hydraulic components, especially servo and proportional valves, are also sensitive to contamination and even a small amount of contamination or fluid degradation by product can quickly damage the equipment.

So how can plant managers and equipment maintenance professionals ensure that they properly protect their company?s investment in a modern hydraulic system? By following the tips below, plant managers, equipment maintenance professionals or purchasing agents can make informed decisions when it comes to selecting the right hydraulic oil and developing the right hydraulic system maintenance plan to help ensure their operations remain competitive and productive.

What to look for in a hydraulic fluid
Right specifications: One starting point for selecting a hydraulic lubricant is the original equipment manufacturers` (OEM) recommendation. This may be specific to the machine manufacturer or the hydraulic component manufacturer, eg, Eaton, Denison and Bosch. The OEM?s recommendation typically provides the appropriate viscosity grade for the expected operating temperature and pressure range, as well as a minimum level of specifications and performance, such as having Denison HF, Eaton M2950, CM P specifications, ISO11158, DIN 51524 HLP or HVLP, and JCMAS HK-1 qualifications.

Right viscosity: Above all, viscosity is the most critical factor when selecting a hydraulic fluid. It is important to match the appropriate viscosity grade to operating temperatures and load conditions that a hydraulic system may undergo on a daily basis. Without the proper viscosity, the system will not operate as designed and the system will likely never reach peak efficiency.

In factoring in the conditions a hydraulic system will face, it?s equally important to realise that OEM-suggested guidelines may not always provide detailed recommendations if systems are subjected to extreme working conditions, such as high or low ambient temperatures. Also, for equipment that is used outside and subjected to both hot and cold extremes, a high viscosity, multi-grade lubricant that features a balanced formulation may be recommended. In such cases, field application advice from your lubricant supplier can be valuable in helping you make the right choice.

Right performance attributes: Given the higher pressures, higher temperatures and smaller sizes of modern hydraulic systems, hydraulic fluids must do more than simply satisfy the correct viscosity and OEM specification. High temperatures and pressures require fluids that deliver oxidative and thermal stability, while preventing system deposits and providing a high degree of anti-wear protection under these extreme conditions. The fluids must also possess excellent air release properties, filterability and seal compatibility. The latest generation of hydraulic fluids can also help increase overall hydraulic system efficiency.

A good option is the new Mobil DTE 10 Excel Series, the latest addition to the popular Mobil DTE family of hydraulic oils. Designed to handle the lubrication requirements of both industrial and mobile high pressure hydraulic systems, Mobil DTE 10 Excel features a revolutionary formulation that delivers exceptional oil life while maintaining hydraulic system cleanliness, enhanced system efficiency, and component protection in modern hydraulic systems.

Mobil DTE 10 Excel Series lubricants help keep hydraulic systems cleaner, extending machine reliability and helping increase productivity through improved machine availability. Proprietary Mobil Hydraulic Fluid Durability (MHFD) testing has demonstrated that Mobil DTE 10 Excel Series? ultra keep-clean performance keeps systems cleaner for up to three times as long as competitive products.

Its high viscosity index and outstanding shear stability enable hydraulic efficiency benefits and hydraulic pump protection over a wide range of operating temperatures. As a result, Mobil DTE 10 Excel Series lubricants provide plant managers and equipment maintenance professionals with maximum equipment protection at high- and low-temperature extremes and the valuable option of using one hydraulic fluid brand across many applications, helping to simplify inventory management.

Hydraulic efficiency benefits can translate to increased machine productivity or reduced energy consumption. In controlled laboratory testing, Mobil DTE 10 Excel demonstrated up to 6 per cent hydraulic pump efficiency increases. And, in controlled field testing, up to a 6 per cent reduction in fuel consumption* per work cycle was documented in hydraulically driven excavators. (*Results may vary depending on operating conditions.)

Best practices for hydraulic system maintenance Keep it clean: Keeping hydraulic systems clean is a must for all environments. The combination of high pressures, small reservoir size and tight tolerance control systems make the exclusion of contaminants crucial in all systems. To keep the system free of contamination, storing and handling oil properly is a good place to start.

Hydraulic lubricants should be stored in a closed container in a controlled temperature environment with adequate spill containment. Transferring hydraulic lubricants should be done through the use of a filter cart and dedicated, sealed clean oil dispensing equipment.

Finally, the hydraulic system reservoir should have a quality desiccant breather and system filter, as recommended in the manufacturer?s guidelines. Some systems utilise auxiliary filtration systems, sometimes known as a kidney loop, that continually ?polish? the hydraulic fluid to maintain system cleanliness.

Oil analysis: As part of routine maintenance, one should be rigorous in checking the health of the hydraulic oil and the hydraulic system itself.

Typically, it is advised that maintenance professionals perform quarterly oil analyses and annual system inspections. For systems that are most critical to a plant?s operation or are subjected to challenging conditions, more frequent oil analysis should be considered.

The oil analysis should include a measurement of fluid viscosity, water content, particle count and dissolved metals to determine how well the system is operating. Examining changes in the oil analysis data over time, also known as `trending?, is necessary to assess the condition of the hydraulic fluid. By trending oil analysis data it is possible to proactively address undesirable conditions before they become problems.

For plant managers and equipment maintenance professionals who want an effective oil analysis program that can also save time and money, there is ExxonMobil?s proprietary online Signum Oil Analysis Program.

Signum Oil Analysis offers customers immediate access and direct control of their lubricant sampling program. With a few keystrokes, users can manage all their oil analysis needs including:

• Updating equipment registrations and select analysis options based on their equipment or maintenance needs;
• Tracking the status of samples at the lab;
• Directing actions based on analysis results, request sample kits; and,
• Sharing critical results with colleagues in a secure, password protected environment.

Visual inspections: Beyond oil analysis, visual system inspections should be conducted regularly to check and document the condition of the hydraulic systems.

Inspection data can be used to establish the optimum time to perform maintenance on critical hydraulic components such as filters, breathers, valves, hoses, heat exchangers and pumps.

Comprehensive leak detection should also be performed, especially if excessive hydraulic oil usage is noted during a routine system inspection.

Conclusion
Today?s hydraulic units are far more sophisticated than their predecessors, and even more so than their older predecessors, New, compact, high-pressure hydraulic systems must be protected with fundamental best practices , such as using a high-performance hydraulic lubricant and implementing a proactive oil analysis programme. The right lubricant and maintenance programme can help improve productivity through efficiency benefits, more reliable equipment performance and increased machine availability.