Lubricant condition monitoring

Lubricant condition monitoring is best accomplished by the analysis of numerical data that are associated with the various fluid failure modes [2]. Numerical data can be analysed by statistical methods to determine the relationship between the various test parameters and their respective fluid and machinery failure modes. In addition, the statistical analysis can be used to determine potential data interference sources, the various alarm limits for each parameter and other criteria to be used in the daily evaluation of used oil. Note that it is important to determine all of the causes for variability in parametric data, just as it is necessary to separate changes due to interfering causes from changes with its associated relevant failure modes. 

Toms, A., A Preliminary Report on the Evaluation of FTIR for Lubricant Condition and Contamination Determination in Support of Machinery Condition Monitoring. I. Synthetic Lubricants , Condition Monitoring 94, Ed. M. Jones, Pineridge Press, Swansea, pp. 520-531, 1994. 

Smolenski DJ, Schwartz SE (1994) Automotive engine-lubricant condition monitoring. In Booser ER (ed) CRC handbook of lubrication and tribology, vol 3., pp 17-32... 

The gas turbine is a complex system. A typical control system with hierarchic levels of automation is shown in Figure 19-3. The control system at the plant level consists of a D-CS system, which in many new installations is connected to a condition monitoring system and an optimization system. The D-CS system is what is considered to be a plant level system and is connected to the three machine level systems. It can, in some cases, also be connected to functional level systems such as lubrication systems and fuel handling systems. In those cases, it would give a signal of readiness from those systems to the machine level systems. The condition monitoring system... 

Condition monitoring is an established technique which has been used by capital-intensive or high-risk industries to protect their investment. The concept has developed radically in recent years largely due to advances in computerization, which offer greater scope for sophisticated techniques. These fall into three types of monitoring vibration, performance and wear debris. The last monitors particulate debris in a fluid such as lubricating oil, caused by the deterioration of a component. 

Infrared spectroscopy is one of the most fundamental tools for the study of lubricant degradation and for condition monitoring of oils during service. 

Tests selected for routine condition monitoring vary between lubricant types and machine application tests. However, numerous tests are almost always performed (viscometry and elemental spectroscopy for instance) while others are optional or exception tests. An example oil analysis test scheme for a particular lubricant is illustrated in Fig. 5. The following are the types of tests commonly performed in laboratories ... 

Fig. 6 illustrates a list of recommended inspection items. Not all the items listed will be appropriate for all plants, and some additional items might need to be added to meet special needs. Also, some of the items listed are not routine, such as the evaluation of used filters and failed parts hence, the work will need to be appropriately divided among operators, lubricant technicians, condition-monitoring technicians, and plant engineering. 

Lubricant Sampling and Analysis The routine analysis of lubricants is a vital condition-monitoring program element, providing information on the health of the lubricant, contaminant ingression, and machine condition. 

Fitch, J.C. Jaggernauth, S. Moisture—the second most destructive lubricant contaminant, Part I— Its effects on bearing life. Proceedings of the JOAP Condition Monitoring International Conference, November, 1994. 

Brown, K. (November 2002) Condition-monitoring of phosphate ester hydraulic fluids. Machinery Lubrication Magazine. 

Traditionally, lubricant property (performance) test methods were used to determine in-service fluid condition. A variety of industrial organizations have standardized a number of physical test methods for this purpose. Utilizing lubricant property tests for condition monitoring introduces several physical and economic problems ... 

One of the most critical and often overlooked problems in oil condition monitoring is the introduction of an incorrect lubricant into machinery lubrication systems. Incorrect oil addition ranges from the introduction of foreign materials such as glycol or different base stock fluids to the introduction of similar oil of a different type or viscosity grade. Whilst incorrect oil is not a lubricant failure mode per se, it can be the root cause of real lubrication problems. 

Van Dam, W., Measuring Reserve Alkahnity , Practicing Oil Analysis, pp. 34-37, Jul 2002. International ASTM Book of Standards Volume 03.06, E2412-04 Standard Practice for Condition Monitoring of Used Lubricants by Trend Analysis Using Fourier Transform Infrared (ET-IR) Spectrometry. 

Ferrography provides the maintenance manager with two critical sets of decision support information condition monitoring, which prevents unnecessary maintenance, and precise trend information, which allows maintenance to initiate repairs before equipment faUute. This is accomplished by the analysis of wear particles in lubricants to determine their size, distribution, quantities, composition, and morphology (form and structure). 

Whether careful conditioning monitoring programme was followed dming run-tring of the items and was preventive mainterrance, including lubrication, was done... 

A programme to prevent business interruption can include planned lubrication, planned preventive maintenance, condition monitoring, statutory inspections, machinery replacement programmes, availability of key spares, identification of key machines, processes, areas, personnel etc. within the organisation, continued supply of raw materials, minimisation of production bottlenecks, and highlighting dependencies on specific items of plant, suppliers, customers, personnel, and/or public utilities (e.g. gas, electricity). 

Hence any form of planned maintenance - whether it be planned lubrication at one end of the scale, or sophisticated techniques such as condition monitoring at the other end - will improve both safety and plant integrity/reliability. 

The film thickness has been determined for a range of steady state bearing operating conditions and the results compared, qualitatively, with published numerical solutions. The method has been shown to be robust and flexible and demonstrates the potential of an ultrasonic based lubricant film monitoring device. 

Tasbaz et al [1] have investigated the use of electrostatic sensors for early detection of scuffing in oil lubricated metal/metal contacts. Electrostatic events were detected prior to severe scuffing and this work demonstrated the potential of using electrostatic detection technology as an on-line machinery condition monitoring system. 

Tasbaz, O.D., Powrie, H.E.G. and Wood, R.J.K., Electrostatic Monitoring of Oil lubricated contacts for early detection of wear. International Conference on Condition Monitoring, 12-15 April 1999. 

Newell G.E., (1999) Oil Analysis Cost-effective Machine Condition Monitoring , Industrial Lubrication and Tribology, Vol. 51, No. 3, pp. 119-124. 

The first method used for wear particle analysis is routine monitoring and trending of the solids content of machine lubricant. In simple terms the quantity, composition and size of particulate matter in the lubricating oil is indicative of the mechanical condition of the machine. A normal machine will contain low levels of solids with a size less than 10 microns. As the machine s condition degrades, the number and size of particulate matter will increase. 

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