Figure 1. Belhaven Focused IR Module
Infrared spectroscopy has long been accepted as an integral part of many oil analysis strategies. The data obtained from infrared spectra can provide insights not readily available from other sources, particularly on specific organic constituents of concern. In addition, the water molecule can be quantified during IR analysis, providing essential monitoring and management information. The basic laboratory technique, Fourier Transform IR spectroscopy, is so widely used that many people use “FTIR” as synonymous with infrared sensing. FTIR has an important limitation, though. Its delicately balanced optics require a controlled laboratory setting, and attempts to use FTIR techniques in real time in the field have not been rewarding. In addition, FTIR measurements are not sensitive to water concentrations below 1000 ppm.
However, there’s another way to perform infrared analysis, and thanks to Belhaven Applied Technologies, Inc. of Kennewick, WA, a new look at in-line infrared data is becoming commercially available for the first time. Belhaven concentrated on the problem of how to obtain IR spectral data in the working environment, directly on a machine lubrication system. Their solution is the patent-pending Focused Infrared Module, or “FIRM” for short (Figure 1).
Each FIRM module is specifically tailored to look at a narrow segment of the IR spectrum. In other words, the module is focused on the well-known unique spectral signature of one constituent of concern rather than producing the familiar broad-band IR spectum. To accomplish this, the FIRM employs a closely-coupled and matched set of IR source, filter and detector. The onboard software controls the unit to produce synchronized stroboscopic pulses in a unique manner that greatly reduces power consumption and heat generation when compared to traditional IR sensor systems. There are no moving parts at all in the FIRM (only the liquid sample flowing through) and no critical optical paths, so it is particularly robust and is unaffected by vibrations and shocks that would invalidate most FTIR tests. Initial test results indicate that the FIRM is sensitive to very small changes in water content of the sample - as low as 50 ppm (Figure 3).
The compact FIRM module is housed in a tough, machined-aluminum frame and is about the size of a coffee cup, making it versatile for many kinds of in-line deployment. The module can be used alone or in sets, depending on the specific data needed. For example, in one version developed for a shipboard turbine monitor, four modules are employed in tandem (see accompanying photograph). One module is focused on the signature wavelength of water in synthetic lubricants, two are dedicated to detecting oxidation by- products, and the fourth channel looks at the oil’s unique infrared baseline. For diesel engines, the selection of FIRM modules might instead include water (in mineral oil base), soot, sulfation and signature TBN indicator wavelengths. Output data are reported in absorbance units, and each individual test takes only a few seconds.
Numerous alternate configurations can be provided, again depending on the specific data needed. The basic idea is to only collect data on those exact portions of the IR spectrum that will yield the needed information. By achieving small size and robust field performance, the FIRM provides a new and unique tool for real-time oil analysis.
Belhaven Applied Technologies is a Washington State corporation that has specialized in engineering, design and advanced product development since 1989. The privately-held corporation provides instrument-related technology, including calibration to NIST standards. The FIRM, which is Belhaven’s first entry into the field of oil analysis, will be available for demonstration at Noria’s Practicing Oil Analysis Conference in October.
For More Information Contact:
Belhaven Applied Technologies, Inc.
415 North Quay Street, Building B
Kennewick, WA 99336
TEL: (509) 735-9446
FAX: (509) 735-3733