The Value of Spectroscopy
FTIR spectroscopy is currently used in virtually all lubricant analysis laboratories. Whereas elemental analysis measures the level of wear metals present, infrared spectroscopy analyzes the molecular composition of in-service fluids. Viscosity measurement, particle counting, elemental analysis and infrared analysis are the main techniques employed for monitoring the condition of lubricants
As a screening tool, the use of real-time, at-site FTIR offers additional potential benefits such as the following:
Need-based AnalysisWhen the performance of lubricating fluid begins to degrade or if earlier analyses indicate the presence of a mechanical problem, it is important to monitor the lubricant more frequently because the process of harmful change can rapidly accelerate.
Because changes in the lubricant as a function of time are not linear, then the time period between analytical tests should be chosen to reflect the current condition of the lubricant, that is, more frequent as the lubricant shows signs of aging. Closely following the condition of in-service lubricant by real-time FTIR allows the fluid to be used to its potential and helps to minimize the risk of mechanical equipment wear.
Certain conditions can cause lubricants to break down quickly leading to catastrophic failure of equipment. For example, an antifreeze leak causes excessive levels of water and glycol to be present in engine oil and these can be readily detected by FTIR. More frequent monitoring of engine oil by real-time FTIR can rapidly catch these contaminants before they have a chance to cause catastrophic damage to an engine. Remote Locations
In remotely deployed equipment, the delay in receiving information about the condition of in-service lubricants may be unacceptable. At-site FTIR analysis minimizes the need to send lubrication samples to off-site labs for condition-based monitoring, which in some cases may be impossible, difficult or costly, and at the same time provides feedback on the sample condition in a timely manner. It is important that equipment operating in these remote locations be carefully monitored because ambient conditions may be particularly challenging.
Return Lubricant to Specs
Real-time, at-site FTIR can act as a supporting analytical technology in programs designed to bring lubricants back to spec via readditization. FTIR is a powerful method for analysis of antiwear and antioxidation additives. More companies are looking to extend the use of lubricants by refreshing critical additives to bring the lubricant back to spec. Real-time, on-site FTIR can be a powerful tool for determining how much additive should be recharged and for monitoring the overall refreshed oil composition.
Real-time FTIR is an excellent screening technology to detect problems with both the lubricating fluid and the lubricated equipment. More frequent screening with FTIR enables personnel to make informed decisions on when to send samples for full elemental analysis, in order to try to pinpoint specific internal machine problems that may indicate excessive mechanical wear. High-load Monitoring
The condition of in-service lubricants in equipment that is stressed due to unusual operating conditions or peak load demands should be monitored more frequently, since high load causes increased demands on the lubricants. Under these extreme conditions, the ability to monitor the fluids more frequently via on-site FTIR can help reduce the likelihood of equipment failure due to lubrication failure. Troubleshooting
Lubricant condition monitoring by at-site FTIR can provide information about the source of mechanical problems in equipment and assist personnel in troubleshooting problems. For example, high levels of soot may indicate that an engine has incorrect fuel-air ratio; the presence of excessive nitration by-products can indicate piston ring blow-by; the presence of glycol and water may indicate a head gasket problem; and unusual levels of oxidation may indicate that an engine is overheating.
QA/QC of Lubricants
At-site FTIR can determine that incoming lubricants are properly formulated, not contaminated in shipping or mislabeled and helps ensure that the correct lubrication fluid is charged into the machinery. It is critically important to use lubricants that meet the equipment manufacturer's specifications. When special lubricants are ordered and shipped, mistakes can occur in formulation or in delivery. At-site FTIR spectroscopy is an exceedingly useful tool for ensuring quality control of lubricants and other incoming materials. As an example, a portable FTIR spectrometer can be used at the loading dock or at the tanker truck delivering fluids to ensure that the delivery matches the expected formulation.
There are two primary versions of the Mobility FTIR spectrometers: the ML (Figure 2) is a highly compact FTIR instrument (8 pounds, 8" x 8" x 4.5"), designed for use in on-site labs. The MLp (Figure 1) is a small (15 pounds, 8.5" x 11.5" x 7.5"), rugged, fully portable FTIR spectrometer to be used outdoors or directly at the source of the in-service lubricant sample. The ML spectrometer uses a standard laptop computer to carry out instrument control and data analysis. The MLp has an on-board, internal computer and is operated via a touch screen. Measuring an in-service lubricant sample is carried out by placing a drop of the fluid on a window located at the surface of the instrument. A second window is rotated into place sandwiching the sample (Figure 3) and the analysis is performed.
The Mobility Spectrometers use a series of algorithms, based on the ASTM E 2412 protocol, for the analysis of in service oil, and thus can measure levels of soot, water, glycol, nitration, oxidation, sulfation oxidation, antiwear and antioxidant additives and fuel dilution. The systems can be used to analyze other lubricants including hydraulic fluid, gear oil and greases. An on-line guide instructs the user on how to prepare the sample for analysis, and then the measurement is initiated with a single command. After analysis of the sample is complete, a report (Figure 4) appears on the screen indicating the specific parameters measured, the pre-set alert or alarm limits for these parameters, and through the use of color indicators, identifies parameters that are out of specification. Specific recommendations are given as to the condition of the oil and the possible mechanical cause of any specification that is not within acceptable limits.
FTIR spectroscopy provides an immediate snapshot of the overall health of lubricating fluids - it is a window to the vital signs of both the lubricants and the equipment that lubricants protect. With A2 Technologies Mobility Series spectrometers, FTIR can now be used where it is needed - at site, where the machinery is in use. This new approach assists maintenance, service and equipment reliability personnel in making rapid, actionable decisions based on objective analytical data.
