Trends in Hydraulic Filtration

By Ulrich Seeger, Head of Product Management, ARGO-HYTOS GmbH, Kraichtal-Menzingen

Proper filtration, without a doubt, plays an important role in ensuring hydraulic systems operate as expected. High-performance filters maintain fluid cleanliness over their entire service life, and customers are clearly requiring longer filter-change intervals, higher reliability, higher efficiencies, and an increased compatibility with new-generation hydraulic oils. Here is a look at some important technology and industry trends, and how they affect hydraulics users.

Filter Performance

While today’s filters may look similar to those of the past, actual performance capabilities have changed a lot.

Consider the important parameters of dirt-holding capacity and pressure loss. A typical ARGO-HYTOS filter element with 10 µm(c) fineness had a specific dirt-holding capacity of approximately 6 mg/cm2 in the year 2000. Today, this capacity has increased by more than 130% to approximately 14 mg/cm2 and, at the same time, pressure loss has been reduced by approximately 50%.

As one example, optimizing the structure of the filter material in the ARGO-HYTOS Exapor Max 2 element reduces pressure losses in the pleat by up to 50% and up to 40% in the filter element. Conversely, at constant pressure loss the filter elements can achieve a flow rate up to 65% higher.

The customer benefits in several ways through improved dirt-holding capacity and increased performance. Filters of the same size now enjoy longer filter-change intervals, improved oil cleanliness and higher nominal flow rates. Or, with the same filter-change intervals, customers can use smaller and, therefore, less-expensive filters. This protects the environment and conserves resources.

Replica Filters

The spread of replica or “knockoff” filters is an increasing trend and has become more and more of a concern. Unfortunately, many users simply purchase such replacement filters based on cost, fit and function, and are unaware or unconcerned how they affect their equipment.

It’s important to note that while many filter elements appear similar, they are actually complex hydraulic components. In addition to parameters like dirt-holding capacity, filter fineness and pressure loss, users should consider other critical operating characteristics, such as filtration efficiency, flow fatigue strength, high dirt-holding capacity, and excellent differential pressure stability.

The filtration performance of replica elements suffers in all the above-mentioned areas. To address the problem, there is a recent trend away from standard filters and toward customized filters so that original spare filters are used and the required oil cleanliness is maintained over the entire service life.

Environmentally Friendly Fluids

In recent years there has been a trend toward using environmentally friendly fluids in hydraulic systems. However, all these oils have a lower conductivity. Newer additive packages considerably affect conductivity as well.

If a non- or low-conductive hydraulic oil flows through a system, electrostatic charge can build at the interfaces between oil and non-conductive surfaces like filter fleece and hoses. Conventional filter material may be selectively destroyed due to discharge flashes and the related high temperatures. Such discharge flashes also lead to premature oil aging, a deterioration of oil performance characteristics and shorter oil life.

To prevent such problems, the charges must be balanced. For this, a special filter element structure has been developed which ensures charge balancing and prevents damaging discharge flashes.

ARGO-HYTOS Exapor Spark Protect completely avoids destructive discharge flashes. The filter elements are compatible with standard filter elements like the Exapor Max 2 and, thus require no modifications to the hydraulic system. Other than added electrostatic-discharge protection, all other filter characteristics remain the same.

It is recommended to use Spark Protect filter elements whenever the electrical conductivity of the hydraulic oil in a system is below 500 pS/m.

System Solutions

Another continuing trend is that hydraulic-filtration manufacturers no longer just supply individual components, they are moving toward providing complete system solutions.
As just one example, we at ARGO-HYTOS supplied a customized suction filter that included a pressure-retention valve for the lubrication circuit, a pressure switch, a temperature sensor and a modular, patented connection system tailored to fit the user’s unique space requirements.,

Industry 4.0

The Industrial Internet of Things (IIoT) and Industry 4.0 are not major drivers for filtration technology right now. But the capability to digitally connect factory-floor devices, such as filters, to the cloud offers exciting possibilities.

A “smart” indicator could link with the machine’s electronic controls to monitor parameters like temperature, flow and engine speed, and potentially track filter behavior, such as during cold start. Users can gain information on whether the system is operating within preset limits; or whether operation is outside the norm, such as the element restricting flow more slowly or quickly than expected.

This technology will be adapted to filtration systems of the future. The trend to improve machine reliability will continue, and it will be backed by the need for more information and sophisticated monitoring and control algorithms. Even machines running in remote locations will be warned of impending breakdown, preventing unscheduled downtime and reducing operating costs.

 

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