Integrating On-site Oil Analysis With Laboratory Analysis

Aaron Black
Tags: onsite oil analysis, oil analysis

Today's tight budgets demand that companies get the most from their oil analysis programs. While oil analysis has become accepted as a useful tool in maintaining equipment, appropriate utilization of the tools by the personnel in charge of these lubrication programs is not always achieved. At some point, a commercial laboratory will likely be needed in the reliability department of an industrial facility. But what about the tools that can be used on-site? Are on-site oil analysis tools already available? Some facilities may have capabilities their personnel don't even know about. Many options are available, and this article discusses how to utilize your entire oil analysis program both externally and internally. Combining the information from available sources to gain a complete picture of equipment performance and what steps can be made to improve it is also discussed.

On-site Testing
On-site testing can reduce costs and improve reliability, even with minimal commercial laboratory use. For example, consider water contamination. It's the second most common force for equipment destruction. It is easily detectable and can be prevented; however personnel must be aware of its presence. Yes, a commercial lab could indicate the presence of water, but for little cost, an individual can monitor water content without having to wait on the laboratory sample.

Viscosity
Viscosity can be tested with several different on-site tools including a visgage. This piece of equipment compares a known reference viscosity to the oil sample. Both oils are stabilized to the same temperature, and testing is performed to an accuracy of 95 percent. Kittiwake offers the DIGI viscometer to test viscosity that works along similar lines, but rather than compare to a reference, calculations provide the correct viscosity.

Keep in mind that on-site viscosity testers and commercial laboratory results will not accurately correspond to each other. This is because most on-site viscosity testing units measure resistance to internal flow and shear, known as absolute viscosity, while commercial laboratories use equipment that tests the lubricants resistance to flow, known as kinematic viscosity. The two measurements can be calculated off of one another, but will never be exact due to the difference in how the test is performed.

Water
By utilizing on-site testing that can be performed with minimal amounts spent on equipment, water can easily be detected. A positive aspect of water testing is users gain a large return for the low cost of equipment. Generally, the only equipment needed is a hot plate. Any kind of heated surface that can reach the predetermined temperature without baking the oil will usually suffice for the quick and dirty test version. A surface thermometer will help in determining the repeatability of the test, but is not required. There are various ways to quantify water's presence, and after repetitive testing for water on a hot plate, it is easy to get a sense of the contamination level.

If having a hot plate or not having enough ventilation is a problem, an alternative is available to run on-site water testing. Calcium hydride test kits with a reported potential accuracy down to 50 PPM can be used. These kits measure the pressure increase of a chemical reaction between the calcium hydride and water that causes the formation of hydrogen gas.

Blotter Spot Testing
Blotter spot testing is a simple and effective way to simultaneously test several oil properties. It is generally used for engine oil, but depending on conditions, could be used in other applications. The blotter spot test can check for dispersancy of the oil, or the oil's ability to keep soot particles from agglomerating. It can also test for the presence of glycol and fuel in an oil. The test requires card stock (standard nonglossy business cards work well), the lubrication in question and time. Simply allow a few drops to soak into the card stock, and the remaining residue indicates the blotter spot test results.

Ferrographic Testing/Filter Patch Microscopy
This type of testing is useful because inspectors can observe the particle types, sizes and configurations. Unfortunately, the results of microscopy are subjective. However, training in ferrographic testing/ filter patch microscopy is becoming more available, leading to more knowledge of what the person conducting the testing should be looking for, and how to report those results in a simple format. Fortunately, this test is based largely on experience, therefore the more a person looks at the patches, the more information he can find.

Ferrographic microscopy is generally one of the few places users can directly observe damage in the equipment. It also allows the user to find damage that has occurred before physically tearing a piece of equipment apart, and helps determine whether the damage is life-threatening to the unit. Fortunately, this testing can be performed with little to moderate expenditures in a budget. A filtering apparatus is needed to release the patch once it is generated, and it must have a vacuum system and a diluent, as well as a way to dispose of the resulting fluid, and the patch must be examined. The third item on this list, the diluent and a way to dispose of it, will likely be the largest cost in this type of testing.

A common diluent used is kerosene, often because it is less flammable than other options. Choosing a filter will depend on the properties of the lubricant. If a user is looking for large metal particles, but the oil has contamination particles of one to three microns, filter patches that allow the contaminants to pass through but still capture as many of the metal particles as possible should be used. These patches are available in laboratory supply stores in multiple pore sizes and dimensions.

Chemical Tests
Several types of chemical tests are available. Some are even viable options for on-site testing. Kittiwake offers solutions for users needing acid number (AN) or base number (BN) testing that are fully electronic; therefore the user will not need additional chemicals. For on-site testing of chemical properties, an electronic unit is the most useful solution.

A negative aspect of wet chemical testing is it typically uses hazardous chemicals, produces hazardous chemicals, or both. A glycol test kit, for instance, uses two different chemical tablets, and when combined with the oil and a diluted sulfuric acid, can produce accurate results. If a plant already has a way to properly handle and dispose of hazardous chemicals, this may be an option; however in many cases it will simply be more work than it is worth, and would be better left to the commercial labs. New testing is being developed every day, and it never hurts to research lab supply companies to see what is available.

On-site Mini Laboratories
A few options are available if one is searching for an all-in-one package to handle several different tests. The Kittiwake oil test center fits these requirements. It tests for AN, BN, viscosity, insolubles and water. A portable version of this unit is also available that could be taken to multiple facilities.

The CSI 5200 is also available to handle multiple tests. The single unit can perform a particle count, check for water, test for magnetic or ferrous particle content and check lubricant properties such as oil oxidation. An additional unit is also available that integrates with the software and hardware that test for viscosity, and a microscope can look at micrograph patches and generate reports.

Other Potential On-site Testing
If considering on-site testing and specific tests that are more complex than most or require special equipment, some options are still available. If particle counting is necessary, several commercial lab particle count manufacturers have less expensive, portable options. Also, some commercial lab infrared equipment manufacturers have the software and hardware to produce several test results, such as BN and viscosity, while simultaneously providing the typical tests many commercial labs require such as oxidation, nitration and soot values. Granted, some of this technology is new, and the typical problems associated with infrared testing remain a challenge, but they are still viable options if on-site testing is necessary.

Combining On-site and Commercial Testing
Combining on-site and off-site testing can be a tricky process. While on-site testing may work great for most equipment, it may not be sensitive enough for others. The following are some helpful guidelines.

When procuring samples for testing, it is helpful for the laboratory to send in a sample every six months, or as the budget allows. At six month intervals, these samples will not allow trending due to the length of time between samples, but will provide the lab some indication should a problem arise between normal sampling. Sampling off-site will give the lab more recent data if a problem occurs that requires professional help in diagnosing, but will result in higher off-site sampling costs. Sampling less often will drop off-site sampling costs, but if the lab's assistance is required, the historical data may not be recent enough to help with the specific problem.

Make sure personnel are aware of equipment that can utilize on-site testing, and what equipment will have to be sent out for testing. If gearboxes are tested for water, an on-site hot plate test may be acceptable to the tolerances that allow long-term operation for those gearboxes. But if a turbine is tested with the same on-site hot plate, chances are that a hot plate is not sensitive enough, and a water problem will be overlooked until it is at a severe level.

Here are some testing possibilities to confirm problems associated with on-site testing:

Viscosity - Confirm laboratory viscosity, oxidation and nitration testing, or fuel testing (if in an engine).

Water - Karl Fischer water test (depending on application) or metals (spectrometer) testing.

Blotter Spot Test - BN or AN testing, metals (spectrometer) testing, laboratory viscosity and/or oxidation and nitration.

Ferrous Metal Test (filter patch) - Metals (spectrometer) testing, direct reading ferrography (DR) or particle quantifier (PQ), as well as an analytical ferrography.

The CSI 5200 reports on specific indices, which cannot always be connected to lab tests, therefore if using this type of testing, the following are some corresponding lab tests that can assist in solving problems:

Wear Index - Metals testing, DR or PQ, possibly an analytic ferrograph if none of these are conclusive.

Chemistry Index - AN, BN, oxidation and nitration, metals testing and Karl Fischer water testing.

Contamination Index - Metals testing, oxidation and nitration, particle count or an analytical ferrograph.

Sensory Testing
Don't forget about the tests that take place every day simply by passing the equipment. Does the oil smell differently than the last sample? Has the oil gotten darker? These questions can help prevent the failure of a piece of equipment, and are as simple as having personnel keep an eye out for these things.

Hopefully this has helped in finding some solutions that may work for your application or at least lead you to a possible solution for on-site testing needs and corresponding off-site testing. Make sure to research your options, and use any resources available to find applicable information. Noria has a forum designated for industrial professionals to ask questions, as well as a database of information on on-site and off-site testing.

Manufacturer's Note:

The Louis C. Eitzen Company, Inc. (manufacturers of Visgage) advise readers that manufacturer's operating instructions should be consulted for proper Visgage usage prior to accurate testing.


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