On-site Oil Analysis - Is It a Replacement For Lab Analysis?

In recent years, there has been an increase in the desire for on-site oil analysis. With the availability of on-site oil analysis tools, a strong fight is waging to determine what the best on-site mini lab should consist of.

Some marketing literature even suggests that on-site lab equipment is superior to having analysis performed off-site at a commercial laboratory. Many believe this marketing has worked because there appears to be a high reliance on the use of on-site oil analysis instruments as the main tool for oil analysis diagnostics.

Many factors must be considered when determining the extent to which on-site oil analysis test equipment will be used. On-site testing can range from having a handheld Visgage-type viscometer (Figure 1) to a full array of commercial-quality test equipment.

The cost of typical on-site test equipment can range from $2,000 to well over $50,000. On top of the cost of equipment, the cost of training, operating, and consumables of an on-site laboratory must also be considered.

On-site oil analysis programs not equipped with commercial-grade test equipment will be the focus of this column.

Equipment-screening Tool

On-site oil analysis is best used as a screening tool for equipment. For facilities that handle large sample volume, on-site analysis can help optimize the efficient use of a commercial lab. For example, a well-established lubrication and contamination control program is likely to return only 15 percent of oil samples, indicating a possible problem.

If this 15 percent can be identified on-site, the cost of commercial laboratory analysis is greatly reduced. Furthermore, the time spent viewing equipment data where the sample indicated a possible problem can be increased with greater focus.


Figure 1. Eitzen Visgage


Fast Reactions Equal Positive Results

With the use of on-site equipment, quick decisions can be made regarding immediate maintenance needs. As an example, take a look at water contamination. If on-site equipment indicates the presence of water, the decision can immediately be made to employ water-removing methods, check for the source of water and make appropriate repairs.

A work order can directly be opened in the CMMS, resulting in a four- to six-day lead rather than if the sample was sent to the commercial lab for analysis.


Unfortunately, on-site equipment does not indicate if water contamination has resulted in an immediate condition that may warrant additional testing, for example, to assess additive depletion caused by water. In this case, a second sample should be taken and sent to the commercial lab for further testing.

Furthermore, informing the commercial lab personnel of on-site results will allow the lab to execute the required exception test. In this case, the lab could immediately run a Karl Fischer water test in lieu of a hot plate, which would allow the sample to be analyzed more quickly by the laboratory. It should be noted that ZDDP and other sulfur-containing additives may interfere with older Karl Fischer procedures still used by some labs.

New Order Testing

Another purpose of on-site oil analysis is confirming the suitable cleanliness and correct viscosity of incoming oil shipments. At a minimum, the viscosity should be checked on every bulk shipment, drum and tote delivered, prior to being placed into service. Unfortunately, there are many instances of lubricant suppliers inadvertently delivering an incorrect product containing the correct paperwork for the order.

On-site particle counting can also be performed on incoming shipments of lubricant. Chances are strong that an effective contamination control program will have target cleanliness levels cleaner than that of the oil being received. It is important to know the level of filtration that must occur prior to putting the new oil into service and that the filtered lubricant meets the desired level of cleanliness.

Ideally, new oil should be at least two ISO codes cleaner than the target value of the equipment for which the lubricant is slated.

Is It Enough?

It is important to understand that even when using on-site instruments to screen samples for potential problems, periodic commercial lab testing should still be performed to establish a trend that can be appropriately monitored. The amount of time between samples will be taken into account when the evaluation is performed.

Getting the most out of an oil analysis program involves understanding the options and deploying cost-effective means for reliability goals. Using on-site lab equipment as a replacement for full lab results with critical equipment is not consistent with best practices. On-site equipment is often limited in the ability to identify precise problems.

I recommend the use of on-site testing as an add-on supplement to a well- established oil analysis program.

The road to a well-established world-class oil analysis program does not contain shortcuts. I welcome the opportunity to assist anyone with fine-tuning his or her current oil analysis program.

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