Clean hydraulics

by Robert J. Taylor

These best practices can extend equipment life and reduce costs

Hydraulic systems are a source of industrial might across industries, from power generation to manufacturing. Hydraulic muscle power lies in the principle that an increase in pressure at any point in a confined fluid creates an equal increase at every other point in the container. That confined fluid is the force behind hydraulic equipment and when it becomes contaminated it can lead to costly repairs and profit-reducing downtime.

Fortunately, the awareness of hydraulic fluid cleanliness has lead to effective hydraulic fluid maintenance solutions that can reduce operating costs and extend equipment life.

Recognizing hydraulic contaminants
Contaminants that cause wear and failure in hydraulic systems include small, clearance-size particulates, water and byproducts of hydraulic fluid oxidation. Dust and dirt are obvious airborne culprits, while moisture contamination may come directly from the environment or through the natural heating and cooling of machine parts and resulting condensation. With very small tolerances between moving surfaces, these particles can cause abrasive wear and the eventual failure of equipment.

How they get in
Contaminants can enter fluids during production, storage, and transfer to equipment. In addition, equipment may already have particle contaminants from the manufacturing process. Since contaminants have so many entry points, it is critical that you have a contamination prevention strategy.

Prevent contamination
It’s significantly more expensive to remove contaminants from a hydraulic system than to prevent them from entering. Some key best practices to prevent the ingression of contaminants are to ensure that equipment seals are tight and superior breathers are installed on all areas where components or reservoirs may breathe with the outside environment.

Most hydraulic systems are equipped with system filters, but these have a limited capacity. Once they are plugged, they go into bypass and provide no protection whatsoever. In order to extend the life of the system filter, dirt and water must be kept out.

To help keep these contaminants out, the breather vent must be in good working order and a desiccant breather/filter/vent must be installed. Desiccant breather/filter/vents are vital because they prevent the ingression of both particulates and moisture from the air that is typically breathed in by an operating component or reservoir.

Storage and transfer
Proper storage and clean transfer are also critical. Drums should be stored in an area with minimized contact with dirt and water vapor. Dedicated product pumps must be kept clean and never placed on the ground when not in use.

Filtering all fluids that are transferred into operating systems is extremely important in helping maintain system cleanliness. These practices can cut costs and extend equipment life, and contamination prevention programs can provide site assessments to recommend handling improvements.

Keeping your hydraulic system in top health means more than keeping a sharp eye out for loose couplings and frayed hoses. If your PMs don’t include regular hydraulic fluid monitoring, testing and filtration and breather inspections, then even if your machines are the cleanest on the floor, it’s just window dressing.

Fluid condition monitoring
Condition monitoring is essential to determine the level of contaminants in hydraulic fluid, whether it’s in storage or in use. Professional fluid analysis by OEMs, major oil companies, and third-party service providers can be performed on the job site while equipment is in operation. Test kits, including electronic Web-based programs, are also available to help track conditions.

The most important element of any monitoring is consistency. A successful program first establishes testing frequency, sampling locations and techniques, and maximum target levels for both moisture and solid contaminants.

When monitoring identifies contamination that is exceeding set targets, it’s time to clean the system through fluid filtration. Fluid filtration is like kidney dialysis: cleansing of the fluid and system to remove harmful particulates and moisture, even while it is in use.

Apply fluid filtration
All hydraulic fluid needs periodic cleaning while in storage and in use. Using high quality hydraulic fluid adds value, because it tends to last longer as it is filtered with contamination removal equipment.

While filtering hydraulic systems is critical, it’s important not to overlook bulk storage tanks, service trucks and storage at satellite locations. Tanks often are vented to the atmosphere with no filter material and service trucks travel from site to site in dirty, wet conditions.

Today, providers of contamination control programs offer tank cleaning and mobile filtration equipment that can hook up to the tank to keep stored fluid up to cleanliness standards. A hydraulic fluid filter system filters particulates and a vacuum dehydration system also removes moisture. Both can be brought to a job site to clean fluids in bulk storage tanks, service truck tanks, reservoirs, and equipment.

Once the fluid is cleaned, desiccant breathers should be installed on all tanks and equipment to reduce ingression of particulates and moisture and extend the time before fluid cleaning is needed again.

Preventive medicine
As demands on equipment continue to increase, companies (like yours, we hope) that focus on equipment and hydraulic system reliability will be in the best position to achieve and maintain peak operating performance. Those businesses that adopt best practices for hydraulic system cleanliness including contamination prevention, fluid conditioning monitoring and fluid filtration will gain powerful business value from enhanced reliability, improved performance and reduced costs.

So, when was the last time your plant’s hydraulics had a thorough “physical?”

Robert J. Taylor is manager of Industrial Sector Marketing for Chevron Products Company.

This article appeared in the December 2007/January 2008 issue of MRO Today magazine. Copyright 2007.

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