On-Site Analysis, Inc. (OSA) has been a leader in emerging diagnostic technologies since introducing the OSA portable laboratory to the oil analysis market in 1986. The easy-to-use high-quality analytical instruments offer users access to special features and benefits without requiring special knowledge or skills, says the manufacturer. The OSA lab is portable and can be shipped to most places in the world. Weighing less than 200 pounds, the OSA is a tool that can be used in-house or on the road.
Figure 1. On-Site Analyzer
The On-Site Analysis Lab
The On-Site Analyzer (OSA) combines four different types of instrumentation and analytical techniques in a desktop-sized enclosure for fast, accurate fluid analysis. When a fluid sample is inserted in the OSA instrument, the technician enters equipment information into the instrument’s internal computer via the touch screen and/or the keyboard. The information entered includes the model, make and other vital information. On the automotive side, the information includes the year, make, model and mileage as well as if the engine oil, transmission fluid or gear oil is being analyzed. Information is collected the first time a sample is analyzed, and is then stored for later retrieval and trending.
Once the sample begins circulating through the OSA, it is analyzed by two to four separate instruments, depending on instrument configuration of the following:
The Optical Emission Spectrometer (OES) seeks to identify metals concentration and compare the current reading to previous readings to determine wear rate changes. The instrument draws in a small sample of the fluid and “hits” it with a spark of electricity. When the contents of the oil are vaporized, the instrument registers the content of each type of element, and converts the reading to a data value, which is reported in parts per million (PPM). Based on its findings, the computer determines if the components have normal or abnormal wear rates.
Infrared Spectrometer (FTIR)
The IR spectrometer seeks to identify constituents that do not belong, such as contaminants. For example, if it detects water, fuel, potassium and sodium at high levels, it concludes that there may be a glycol gasket leak, because the coolant system is the only place these contaminants should be present. The infrared module features an optical light source, flow-through cell, and detector. Light at wavelengths specific to physical parameters of interest are transmitted through the oil in the flow-through cell onto the detector and measured in absorbance units. The OSA computer also matches that information to the normal information for that specific item. The IR instrument also checks the lubricant for oxidation, nitration, soot and fuel concentrations.
Oxidation is a measure of the aging of the oil, and is a result of the interaction of the hot oil in the component, with oxygen in the air. These values increase with use, and the maximum levels will vary due to stresses on the oil and the component type.
Nitration is the reaction of the oil with combustion by-products of nitrogen. These reactions tend to become more pronounced at higher temperatures. Generally, this parameter is mainly measured for gasoline engine oils, and high levels of nitration are considered undesirable because the materials formed are precursors to oil sludge and varnish formation on metal surfaces. The measurement is sensitive, and is accurate to one unit or less (units used are the same for oxidation, absorbance/cm).
The OSA infrared method measures base numbers (BN) soot and insolubles. BN is reported based on typical base number values (starting values in the range seven to 14) for API SH/SJ and CF service. Soot and insolubles are reported as overall light absorption. The test is relatively sensitive, and an accuracy of approximately 0.2 percent is possible. The actual levels considered to be undesirable varies between engine manufacturers, and it is necessary for the user to know the recommended condemnation limits. Also note that insolubles can include soot, inorganics (such as sulfates) and insoluble oxidation products, all of which are reflected in the instrument reading.
OSA offers an optional dual temperature viscometer, and through an estimate that is derived from other standard IR data inputs. The optional viscometer measures the viscosity at both 40 cSt and 100 cSt and can provide a viscosity index if desired. This method has a precision of ±0.2 cSt (accuracy of better than 1 cSt) over the range of five to 100 cSt. The OSA can also provide estimates of viscosity from the existing IR data. These estimates are based on measured soot, oxidation, nitration and fuel, all of which affect the lubricant relative to its known parameters. A calculated starting viscosity is provided as a standard feature.
A particle counting option is available for industrial and mining applications. The OSA Lab offers a PAMAS particle counter, which is strategically placed within the OSA Lab cabinet. With this option, the OSA can be used in field operations as well as repair shops, manufacturing locations and lab facilities.
Using reporting options of ISO 4406:1999 4 µm, 6 µm and 14 µm based on ISO 11171:1999 calibration and also utilizing the option of ISO 4406:1987 (2 µm), 5 µm, and 15 µm based on ISO 4402 calibration. Particle analysis and sensor cleaning are carried out by background tasks and operate seamlessly with other analyses on the OSA. The operator has the flexibility to enable/disable particle counting system for each analysis.
The OSA lab has many options of reporting the data. With its unique database functionality, the OSA lab can produce numerical data, text data or combined data in the final results. Results may also be exported directly to the online reporting Web site at mylubetrak.com, a separate entity of On-Site Analysis. LubeTrak offers a complete web-program for posting oil analysis data for any size company, for one to 100,000 sites. This allows 24/7 access to reports and requires only Internet access to a personal computer.
Some additional features include the flexibility of automatic e-mail alerts, robust charting, history downloads; and reporting options in Excel outputs, PDF, FlashPaper and Microsoftword formats. LubeTrak offers each industry the flexibility to customize its needs from one piece of equipment to more than 10,000 pieces of equipment, and over as many accounts and locations as needed.
Conforming to Standards
The OSA parallels most of the standard ASTM methods for used oil analysis, and in practice, follows similar procedures as used in the Caterpillar SOS program. The wear metals analysis is performed on the oil directly, without the need for dilution (as required by ASTM D5185) and is comparable to D6595. The spark emission method used on the OSA also provides comparable results to the ICP method described in D5185; however, the values obtained are usually 10 to 30 percent greater than those obtained by the method. The main reason for this is that ICP emission has different particle-size sensitivities.