Recent Developments in Online Oil Condition Monitoring Sensors and Alignment with ASTM Methods and Practices

Abstract

Oil condition monitoring is a vital part of integrated asset health management. With an increasing impetus toward real-time decision making, delays incurred in offline laboratory oil analysis are becoming less acceptable. At present, several oil quality parameters can be monitored by commercially available sensors, and active research and development programmes are being pursued by both academic and industrial researchers to develop robust, cost effective sensors for the remaining key parameters. Published (active) ASTM methods or practices do not yet cover the sensor technologies employed or under development, although work is in progress to address this deficit. This paper presents an overview of currently available oil condition sensors and looks at some recent developments, particularly in the following three areas: contamination by metallic wear debris, measurement of total water content, and determination of in-service oil viscosity. In each case, quite different technological solutions have been adopted. Where applicable, alignment and overlap with existing ASTM methods and practices will be reviewed and future directions indicated. Recent improvements in the sensitivity of inductive particle counters have enabled the detection of individual ferrous particles down to the sub-100 μm diameter regime and close to the 100 μm diameter mark for non-ferrous metals. Experiences of particle counters in wind turbine applications have shown the potential for enormous benefits in failure prevention. One standard practice covering the installation, operation, and requirements of such devices is published and a second is currently in draft mode. Online sensors utilising infrared transmission measurements recently have been developed by two independent companies. The systems are targeted primarily at marine diesel engine installations, although the method is not restricted solely to these applications. Maximum water content measurable depends on both the optical path length and the cleanliness of the oil. For marine applications a practical upper measurement limit of 1 % by volume has been adopted. In the system described here, a correction methodology, correlating to an accepted Deutsches Institut fu¨r Normung-Fourier transform infrared standard, has been adopted to cope with oils contaminated by soot. Soot loading increases the opacity of the oil, causing a concomitant reduction in the maximum water content measurable. The correction procedure increases the accuracy of the water content measurement and additionally provides a determination of the soot content. Commercially available viscosity sensors include both the oscillating piston type and high frequency oscillating crystal designs; however, a cost effective device employing a low amplitude, mid-frequency vibrating sensor element has been developed recently. Key features include accurate measurements over a very wide viscosity range and an operating range that covers combustion engine oil temperatures and pressures. Correlation with existing ASTM methods and practices is presently limited to calibration aspects only.

Study of on-line condition monitoring and fault feature extraction for marine diesel engines based on tribological information

“…In the previous work 6–10 on the fault diagnosis using oil analysis, the relationships between typical parameters of the wear debris and the wear mechanisms of machinery faults have been investigated. Based on this knowledge and other research experience reported in Lunt 11 and Yan et al, 19 this article has further developed a remote on-line fault diagnosis system using the tribological information for the industrial application on the marine diesel engines.…”

“…10 However, traditional off-line laboratory oil analysis delays the decision-making, and hence, it has limited practical application. 11 With an increasing demand for real-time execution of oil analysis, the on-line oil monitoring sensors and detection systems have attracted great interest for both academic and industrial researchers. Markova et al 12 investigated an on-line monitoring of oil viscosity using a novel vibration method.…”

“…Some other recent developments in on-line OCM sensors have been reviewed by Lunt. 11 As for the detection systems, Hu et al 16 reported a new development of the on-line state monitoring and fault diagnosis system for the power transformer. The General Packet Radio Service (GPRS) was adopted to realize remote communication of the on-line monitoring system.…”

Improving hydraulic excavator performance through in line hydraulic oil contamination monitoring

“…In addition, the interval periods are often too lengthy to capture the critical moment just before failure [16]. Furthermore, Lunt claims that offline laboratory oil analysis is becoming less acceptable, as maintenance strategies are developing more towards real-time decision making [63]. Hence, there is an arguably a need for OEMs to improve CBM programmes by addressing these concerns.…”