Looking Through the Eyes of Onsite Contaminant Monitors

Jim Fitch, Noria Corporation
Tags: contamination control, onsite oil analysis, particle counting, wear debris analysis

Without the lens of a microscope, bacteria and viruses might only be recognized as painful symptoms of sickness and disease by those who are infected. Just as technology is an important enabler in human pathology, it also serves in the detection and diagnosis of a host of machine health issues, including the invasion of lubricant contamination.

However, for most machinery maintainers, the threat posed by fluid contamination runs contrary to human intuition. Just like a viral infection, in lubrication, it’s what we can’t see that hurts us most. The naked eye is generally blind to the destructive potential of most types of contaminants. In fact, none of our “unaided” human senses can be relied upon to detect and recognize significant concentrations of contamination.

When I first entered the oil analysis field in the 1980s, portable and user-level oil analysis technology was years ahead of its time. This is not so today. Contaminant monitoring instruments have advanced rapidly in the past two decades as has the awareness of its importance. What was previously only the domain of analytical chemists is now an essential maintenance tool available to field technicians and condition monitoring specialists. Thankfully, the “now generation” is largely a population of sophisticated consumer electronics users who also have an insatiable appetite for instant information.

Outfitting Your Toolbox

Astute lubrication professionals know that measurement and feedback are critical to contamination control. There are a variety of user-level contaminant monitoring instruments and methods to gain quick readings on lubricant cleanliness, dryness and other contaminant levels. Putting the right tools in the hands of maintenance teams enables far greater awareness of transient contaminant conditions and the need for a quick, corrective response.

As with any oil analysis program, the process should begin by identifying the machines and lube points to be included for contaminant monitoring. Don’t overlook the importance of properly located live-zone sampling ports. Consider installing both primary (routine analysis) and secondary (troubleshooting only) sampling ports on circulating systems. Document the appropriate sampling procedure and train your staff accordingly.

In selecting contaminant monitoring instruments, emphasize “ease of use” as being of greater importance than precision and diverse functionality. Often the simplest of instruments will prove to be the most effective from a maintenance perspective. The reason is that they are used more frequently and the data is often easier to interpret. In the world of reliability, tests of moderate precision but performed frequently will almost always win out over high-precision but infrequent analysis of lubricants.

Because of the dozens of available instruments at wide-ranging costs, you would be well advised to be a smart shopper by first defining needs and comparing options. As an aid in navigating the process, I’ve included a few pointers below:

Target contaminants: For most machines, particles and moisture are the most serious contaminants, so this is an essential starting point in setting up an onsite laboratory. Fortunately, there are numerous particle counters, patch test kits and moisture analyzers from which to choose. Many of these instruments have gone through years of refinement to adapt to the needs and expectations of the user community. Additionally, there are glycol kits, fuel dilution testers, soot instruments, microbial contaminant testers and even field acid-number (AN) kits.

Daily sample volume: Many user-level instruments have slow throughput times – say 10 to 20 minutes per sample. This is not a problem if the expected sample volume is low. However, if high sample traffic is expected, then instruments that can quickly process samples are going to be an important requirement for quick data turnaround.

Range of sensitivity: Before you select your onsite contaminant monitoring instruments, it would be advisable to quantify your alarm levels. Most instruments have upper and lower limits of sensitivity. Your alarms and limits need to fall within the instruments’ dynamic range of performance.

Wet chemistry: Not all onsite oil analysis instruments require the use of solvents and reagents. Many chemicals have special handling and disposal requirements. Ventilation may also be needed. In most cases, instrument options exist that don’t require the use of dangerous solvents and reagents.

Portable vs. benchtop instruments: Not all instruments require a laboratory countertop to operate. Many instruments are portable or at least “luggable”. They can be used directly on the machine without the need of a sample bottle or near the machine from a bottle sample. For large plants with many lubricants in non-circulating applications, the best option is often to set up a small bench-level laboratory where samples can be periodically analyzed.

Microscopic analysis: While automatic particle counters are a mainstay of most onsite oil analysis laboratories, they almost always need to be flanked by microscopic analysis for particle identification. Microscopic analysis enables particle color, shape and texture to be evaluated. To do this, a simple means to make membrane patches should be made available along with a suitable microscope and lighting.

Calibration and check fluids: Even the most basic onsite oil analysis instruments need to be checked periodically for precision. Source check fluids of known properties and contaminant levels to provide a quick means to confirm instrument accuracy.

Target fluid compatibility: All instruments are going to have basic application limits relating to the fluid types with which they will be used. These include viscosity range, fluid opacity (darkness), chemical compatibility and interferences (e.g., from additives, soot, water, air, etc.) among others. Verify that the target fluids are suitable for the instruments being considered.

Important and Effective

Onsite instruments have changed the landscape of the oil analysis industry in the past couple of decades. Users are now empowered to perform quick and frequent screening tests themselves. The most important include the assessment of fluid contaminants. This enables the routine practice of proactive maintenance. In my opinion, proactive maintenance stands alone as the most effective benefit-generating strategy for machine reliability. To be performed successfully, there is an absolute requirement for continuous feedback from onsite measurement tools such as contaminant monitors.


About the Author

Jim Fitch, a founder and CEO of Noria Corporation, has a wealth of experience in lubrication, oil analysis, and machinery failure investigations. He has advised hundreds of companies on developing their lubrication and oil analysis programs. Contact Jim at

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