Fluid Power Journal

The Value of Fine Fiber Filtration Media

By Samuel Kaye, Donaldson Company.

In nearly every industry that uses heavy machinery, efficiency is king. Whether you’re talking about man-hours, fuel usage, equipment wear and tear, or anything else, the ultimate goal is to get the most out of everyone and everything on the job site. Nowhere is this truer than in the mining and oil industries, where a single hour of downtime can have drastic ramifications on the bottom line. 

In these industries, every edge matters, so you need to look in unexpected places to find true efficiencies. In this case, we’re looking at hydraulic filtration. Modern hydraulic equipment is vastly more complex than it used to be, with higher pressures and tighter tolerances the exception rather than the rule. Hydraulic fluid contaminated with even microscopic particles can cause component failure from long-term wear or even sudden failure that leads to costly unplanned downtime. 

“Better” filtration isn’t always better

Synthetic high-efficiency filtration media has evolved to be incredibly effective at catching contamination that can cause damage to expensive equipment. But until very recently, there’s been a downside to these media: While they limit contamination, these medias can be very restrictive to flow, which causes a high pressure drop that can lead to power decreases.

When you’re lifting a bucket on an excavator at a coal or gold mine, the last thing you want is a loss of power.

So how do we reconcile the need for filtration that ensures cleanliness levels for hydraulic fluid but doesn’t impede hydraulic power?  There’s a lot to consider, but filtration companies are constantly researching potential solutions. Multilayered, fine-fiber media like Donaldson Alpha-Web™  is one solution that can pay immediate dividends.

Multilayers, multi benefits

Modern hydraulic circuits have complex, sensitive system designs that include electrification, precision tolerances, high pressures, and high pump speeds. These circuits are built to meet operational efficiency targets for productivity, service intervals, and downtime, and likely need to meet environmental impact targets as well. All of these factors mean that there’s a tiny needle to thread to get the most out of a hydraulic system. The fluid must be perfectly clean and stay clean for as long as possible without impacting the power of the equipment.

The sensitive components of modern hydraulic systems are, unsurprisingly, costly to maintain and even costlier to replace. A single general servo valve can cost more than $2,000 just for the part. A piston pump can cost well over $3,000. But the more important number is the lost opportunity cost. What does it cost a mining operation to have an excavator or haul truck out of service for a day? 

Keeping pumps running efficiently is especially important. As the (nearly literal) beating heart of a hydraulic system, if a pump goes down, the entire system goes down, which means that the equipment is out of service until the pump is operational again. According to a National Institute of Standards and Technology study*, the average maintenance cost for a hydraulic pump is $24 per kW per year ($18 per hp per year). That means that a hydraulic pump with a 225 kW (300 hp) motor can cost $5,400 annually just in basic maintenance. Multiply that by the number of pumps on the equipment and the number of units in your fleet, and you can see how quickly these costs add up. Simply by improving by two ISO codes over synthetic media, you get hydraulic fluid that’s four times cleaner than it was previously. That change in cleanliness can extend component life by nearly 60 percent. What’s that worth to an entire fleet?

75 percent of all hydraulic component failure is caused by contaminated or aging fluid.§ Keeping these vital components running efficiently is the primary goal of effective hydraulic filtration. Multilayered fine fiber media can clean hydraulic fluid to a microscopic level while not limiting fluid flow and power. But how clean does fluid need to be to protect these components?

How clean is clean enough?

 Figure 1 above demonstrates ISO4406 guidelines for fluid cleanliness regarding certain components of a hydraulic system in relation to internal pressures. For instance, a prefill valve pump operating at less than 21 MPa (3000 psi) requires fewer than 5000-10000 particles of 4 µ or larger, 1300-2500 at 6 µ or larger, and 160-320 at 14µ or larger per ml of fluid. Just for perspective, limestone dust can be smaller than 10µ. A speck of coal dust is a 14µ particle. A human hair is 40µ in diameter. So, you can see that even microscopic particles should be kept out of hydraulic fluid!

Hydraulic filtration for real-world conditions

Much of the available legacy hydraulic filtration media meets these ISO ratings, but they meet them in controlled settings. As anyone who has operated on a construction site can attest, real-world conditions are far from controlled. Hydraulic fluid is subject to constantly varying flow rates, which offer plenty of opportunity for contamination and pressure drops, and filter media needs to be able to handle both without losing effectiveness. Whenever there’s a change in flow rate — when the clutch engages, when the engine speed changes, when the joystick actuates an attachment, etc. — legacy synthetic medias can cause trapped particles to dislodge and get into the system to wreak havoc. A multilayer fine-fiber media like Alpha-Web that traps and locks contamination stands up to these flow-rate changes much more reliably than previous filtration media.

Complex protection for complex systems

As hydraulic systems evolve to be more complex and intricate, filtration media also needs to evolve to be more effective at protecting the components from contamination. Effective filtration needs to:

  • Clean hydraulic fluid on a microscopic level
  • Withstand the rigors of ever-changing flow rates
  • Trap and lock particles
  • Allow fluid to flow freely despite conditions

A single hydraulic filter that cleans fluid effectively with multi-layer fine fiber media can save a mining or oil fleet in component wear costs and by limiting unscheduled downtime of equipment. What’s more efficient than that?

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