Used Oil Analysis

Oil and machine condition detection and trend tracking systems for predictive and preventive maintenance operations

The importance of oil analysis in maintenance applications

Predictive or preventive maintenance concepts help to determine the assessment and planning activities of repair and maintenance activities by gathering periodic data on machinery and equipment health.

We can refer to oils and other lubricating liquids as life-forms of machines. Analyzes of these lubricants provide information on the wear status, contamination and suitability of the oil for use within the machine / equipment. Based on the results and trend reports from these analyzes, the maintenance engineers are able to stop, repair, maintenance, Ensure that important decisions are taken in advance and prevent possible failures and stops.

With oil analysis, contamination control, error analysis, machine-dependent maintenance and different oil mixes are prevented.

Attachment of Wear, Pollution and Additive Elements by Elemental Analysis

The display of elements is an important part of fat analysis and status monitoring programs. The most common technique used for elemental analysis in used oils is optical spectroscopy. The spectroscopy systems allow the determination of the wear and contamination elements, which are formed in the machine over time and which are mixed into the oil, at the ppm level.

Wear metals (iron, aluminum, chromium, copper, tin, lead, silver, titanium, nickel, etc.), oil additives (calcium, barium, zinc, phosphorus, magnesium, boron, molybdenum etc.) Certain contaminants (silicon, sodium, potassium, etc.) are detected periodically. Trend graphs derived from the changes in these elements are used to determine system health, control of oil additives, leak and / or filter status.

Several different types of spectrometer systems are used for displaying elements. These are Rotational Disc Electrode (RDE) Atomic Absorption (AAS), X-Ray Fluorescence (XRF) and Inductively Coupled Plasma (ICP) emission spectrometers.

Particle Counting, Imaging, Classification and Ferrous Content

Oil pollution is a very important parameter especially in industrial machinery and it is an element that defines both the oil life and the life span of the work machine and the frequency of failure. The most important factor affecting the quality of hydraulic and gear oils used in construction machinery is particle pollution. Because particle pollution affects the chemistry of the oil with the elements it contains, it causes erosion with its tribological and rheological properties. It is difficult to set a general rule on pollution. However, limit values for ISO4406 14/11 (NAS 6 or 7) for hydraulic oils and ISO4406 18/15 (NAS 9) for gear oils are used. In fact, these limit values may vary depending on the machine type. In particular, hydraulic oil used in servo-valves has been searched for 12/9 times. In terms of pollution, a number of particles of a certain average micron size are usually used on a milliliter oil sample. The ISO4406 standard for pollution monitoring was last updated in 1999. In this standard, the R “Number of Ranges” used in R1 / R2 / R3 varies from 1 to 30 and there is a ~ 2R link between the number of particles in the 1 mL oil sample. This analysis in our laboratory is based on the dimensions of the particle in the oil using the laser system in the vacuum and pressure system and in accordance with ISO 4406 / SAE AS 4059 – NAS 1638 methods.

Monitoring Oil Status with Infrared Analysis

Another aim of oil analysis programs is to monitor the status of the oils. Deterioration and contamination of lubricating oils should be checked periodically by maintenance engineers and the remaining life and suitability of the oil should be determined. The data obtained from the analyzes allow to obtain a lot of critical information such as leakage in the machine, removal of the risk of corrosion due to oil health, or determination of the quality of combustion.

There are many different analysis systems for fat condition monitoring. The need to use different systems for the detection of each parameter makes use of Infrared spectrometer technology for these analyzes. The number of acids, the number of bases, the amount of oxidation, the amount of water, the amount of water, the nitration, the sulphation etc. related to the oil condition with the infrared systems. To be obtained in a single analysis given, time consuming and consuming laboratory devices that require the use of this area prevents.

By infrared analysis and 30 second analysis, the chemical condition of the oil used and the deterioration data of the additives are determined to prevent possible failures. At the same time, the reduction of the damage caused by the widespread unnecessary oil changes is a significant advantage of the oil condition monitoring.


Viscosity determination is the most important analysis in terms of determining the physical state of the oil, especially the oil. Determination of load carrying capacity and flow characteristics of the oil is determined by this analysis. The manual viscosity measuring tubes are economical and are suitable for use with low sample quantities. Automatic viscosity measuring devices provide automation at different levels and measure without any intervention.

Since significant changes in oil viscosity directly affect the ability to lubricate, the viscosity value should be constantly monitored and controlled. As stated in the ASTM D445 standard, which is most commonly used for viscosity determination, the viscosity of multigrade engine oils must be changed from 30% in terms of viscosity to 10% in hydraulic oils.

Fuel Dilution: Control of Oil Fuel Mix

Burning inefficiency that occurs over time in internal combustion engines and worn outs at bearing ends cause unburned fuel to leak into the oil. These fuels, which are quite low compared to the flash point and viscosity value oil, cause oil viscosity and oil viscosity and reduction in flash point levels. Uncontrolled fuel dilution in an engine primarily reduces viscosity and increases engine inefficiency and wear; At the same time the critical point of the flash point is reduced and the glare inside the engine creates huge financial and human damages. This is why fuel dilution has an important place in the concept of maintenance.

GC-MS, FTIR, Flash Point, etc. for fuel dilution detection. Methods can be used. Given the cost of these systems and the time and space required for analysis, a compact and fast system is required. For this reason, chemical micro-sensor technologies have begun to be widely used. These systems, which have reached the level of speed and detection capability requested by NATO Orders, have begun to be widely used in military and heavy machinery industries.

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