FT-IR equipment, which is up to date, is constantly being used in the OELCHECK laboratory. For every lubricant sample examined by OELCHECK, an IR analysis is part of the mandatory program. It provides important information about the condition of the oil and possible impurities. New and current devices are faster and provide even more precise values, especially for synthetic oils, which are being analyzed more and more frequently.
New IR instruments are also geared toward a fully automated sample changer with powerful processors and increased memory capacity. Up to 60 lubricant samples per hour can easily be analyzed. This will enable us to meet the constantly increasing number of analyses in the OELCHECK laboratory in the future as well.
In contrast to older instruments, where each sample is still applied individually to a crystal, the ATR cell, in modern instruments the oil flows into a 0.1 mm thick cuvette designed as a flow cell. Clustered infrared light is beamed through the cuvette. A detector records the vibrations of the electromagnetic bonds of the molecules present in the sample, which are altered by the IR light. The result is an IR spectrum.
The IR device compares the spectrum of the current sample with the data of an assigned fresh oil. If information on the oil type is missing, the program selects the oil whose "fingerprint" best matches the spectrum of the sample from thousands of possible fresh oils in the library created by OELCHECK. In most cases, the used oil spectrum deviates from the fresh oil spectrum at certain wavenumbers. From the band intensity or the area under a band in a given wavenumber range, the type and amount of contaminants in the oil such as water, glycol, fuel and soot, or the amount of oxidation, nitration and sulfation can be calculated using the mathematical method of the "Fourier Transform" (hence FT-IR).
With constantly updated equipment, faster searching, finer resolution of curves, and easier programming of algorithms to convert IR units of length or area become possible. By storing the spectra in the network, OELCHECK engineers can very easily make a comparison with another fresh oil or with an oil blend when creating the comment. With their experience in the field of mineral and synthetic oil IR spectroscopy, they are able to interpret the spectra accurately.