Reducing maintenance and downtime costs are a concern for almost everyone in the industrial distribution business. The answer to that troubling problem could be as easy as a customer's oil analysis protocol.

Well-documented case studies have convincingly demonstrated that the practice of used oil analysis is a sound approach to reducing those costs. But for most users, these low-cost rewards have evaded their best efforts, simply due to common implementation errors. A success in lubricating oil analysis consists of a series of fine lines that must be carefully navigated.

So many manufacturers are unsure of the real purpose of oil analysis. Is it a strategy for telling them when to change oil? Do they use it to indicate when and where machine parts fail? Is it an approach to reducing the severity of machine failure or frequency?

Most often, users associate an oil analysis program with an alert system for oil failures. This is less important than the more immediate objective of failure avoidance. The strategy of failure avoidance is found in proactive maintenance, and that alone should be the central focus of an analysis program.

Three steps are necessary to ensure this proactive maintenance, which is, by definition, a continuous activity of monitoring and controlling machine failure root causes.

The first step is to set a target or standard associated with each root cause. These targets help maintain an environment that is conducive to prolonged lubricant and machine life. In oil analysis, the important root causes relate to fluid contamination, including particles, moisture, heat and glycol, and additive degradation.

The second step often includes an audit of how these fluids become contaminated, and then systematically eliminating those entry points. Better filtration and the use of separators often are required.

The third step is vital, and is the action element in any oil analysis program. The control of the root causes within the targets only is assured when constant feedback is supplied. Oil analysis provides the feedback loop so that, when exceptions occur, actions can be taken.

Using a proactive maintenance strategy, contamination control becomes a disciplined activity of monitoring and controlling high fluid cleanliness, not the crude activity of just trending dirt levels. Organizations that embrace this "cleanliness ethic," stand to benefit the most from oil analysis.

When the life extension benefits of proactive maintenance are flanked by the early-warning benefits of predictive maintenance, a more comprehensive condition–based maintenance program results. Abnormal levels and types of wear particles are an embedded "SOS" signal to maintenance personnel that a machine's internal surfaces are distressed.

In the world of oil analysis, the ability to extract and distill useful information from a small sample of oil depends on the quality of the raw data captured within. This seems like a straightforward task, but experience has taught us that there are obstacles to overcome. The technology of oil sampling specifically addresses the saying, "garbage in, garbage out."

From a practical standpoint, optimal performance in oil sampling depends on succeeding in three areas: maximizing data density, minimizing data disturbance and minimizing data contamination.

The added challenge is that the data in the oil sample is invisible to the human eye. Therefore, without a well-planned course to follow, oil sampling activity is analogous to "flying in the dark." The following is an overview of some of the essential precepts toward getting quality oil samples:

• Real estate agents tell us that the three most important considerations in selecting a property are location, location and location. The same factors hold true for oil sampling. In circulating oil systems, the best location is a live zone of the system, upstream of filters, where particles from ingression and wear debris are the most concentrated. Usually, this means sampling from fluid return or drain lines.
  In some cases, where oil drains back to sumps without being directed through a line (e.g., diesel engine), the pressure line downstream of the pump (before the filter) must be used. Always avoid sampling from dead zones, such as static tanks and reservoirs. Splash, slinger ring, and flood-lubricated components are best sampled from drain plugs after considerable flushing, or, preferably, using a portable circulating off-line sampler.
• Once a sampling point is properly selected and validated, extract a sample without disturbing the integrity of the data. When a sample is pulled from turbulent zones such as an elbow, the particles, moisture and other contaminants enter the bottle at representative concentrations. In contrast, when sampling from ports positioned at right angles to the path of the fluid flow, the higher density particles follow a forward trajectory and do not enter the sampling port. This condition can reduce particle counts by ten-fold or more.
• Machines should be sampled in their typical work environment, and ideally while they are running with the lubricant at normal operating temperature. Likewise, during, or just prior to, sampling, machines should be run at normal loads, speeds and work cycles. This ensures that the wear debris that is typically generated in the work environment is present in the fluid sample.
• Similarly, it is important that particle and moisture ingestion from the atmosphere, due to ineffective seals and breathers, also be at representative levels. Such contaminants and wear particles typically settle to tank bottoms and pipe walls when systems are cold and inactive.
• The routine monitoring of oil contamination is an important objective in oil analysis. The same kinds of contaminants found in oil also are found in the atmospheric work environment. Therefore, considerable care must be taken to avoid the risk of "contaminating the contaminant" in the sample. Once atmospheric contamination is allowed to contact the oil sample, it cannot be distinguished from the original contamination.

There are many techniques to minimizing sample contamination. These include certified bottle cleanliness, probe-tube bottle attachments, ample sampling valve flushing, and frequent cleaning/flushing of portable sampling devices. What might generally seem like a minor corruption of these important measures can greatly compromise the integrity of an oil analysis program.

The time and money spent on correct sampling protocol, thereby ensuring the quality of an oil sample, will achieve a great return on investment when the benefits of oil analysis are totaled. This is best accomplished by proper training for all those involved in sampling activities.

Ming Xu is a product manager at Rockwell Automation, Westerville, Ohio. For more information, call (740) 548-5733, ext. 3372.