Used lubricating oils

The analysis of used lubricating oils is accepted as an effective and practical means of monitoring engine wear. It allows preventative maintenance to be carried out at convenient times when needed and avoids the expense of major breakdowns and excessive lay-offs. Navies, air-forces, air-lines, rail companies and many companies with large truck fleets make use of this diagnostic aid. 

Because of the nature of the metallic constituents in the oil, suspended particles of metal or alloy, agreement between laboratories and individual instrumentation is often poor. However it is not the absolute concentration level of an element which is important but the change in concentration with time. A history of the particular engine being monitored is required, and a sudden change in wear metal content is indicative of excessive wear and indicates that maintenance is required. It is therefore useful if the same instrumentation is used for a particular analytical procedure such that values obtained may be compared over a period of time. 

In used lubricating oils the wear metals are normally present in an extremely finely divided form and thus flame chemistry, similar to that for metals in true solution, is normally found. However, in some oils, such as those from heavy duty equipment or where excessive dust has been accumulated, larger particles may be present. In these cases more accurate results may be obtained by employing an ashing procedure to ensure proper dissolution of the metals (see Section II.D). 

Finally, in order to obtain representative samples of used lubricating oil for analysis it is necessary to run the engine for some time prior to sampling. This is of prime importance since all subsequent operations will be invalidated by poor sampling techniques. 

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Oil whose characteristics have changed since original manufacture and which is suitable for recycling. This is an umbrella category that includes used lubricating oils of all types as well as dirty or contaminated fuel or other oils that can be economically recycled. 

Most rotary screw compressors use lubricating oil within the compression space. This oil is injected into the compression space and recovered, cooled, and recirculated. The lubricating oil has several functions... 

Air reservoirs are designed to receive and store pressurized air. Pressure regulating devices are installed to maintain the pressure within operational limits. When the air reservoir is pressurized to the maximum pressure set-point, the pressure regulator causes the air compressor to off-load compression by initiating an electrical solenoid valve to use lubricating oil to hydraulically hold open the low pressure suction valve on the compressor. 

Reconditioning is the removal of contaminants and oxidation products (at least in part) but not previously incorporated additives. It may also involve the addition of new oil and/or additives to adjust the viscosity and/or performance level. This process is sometimes referred to as laundering or reclamation . The method treats used lubricating oil to render it suitable for further service, either in the original or a downgraded application. Two types of treatment are generally employed. 

Sec-Feed A process for converting used lubricating oils into feeds for catalytic crackers. Essentially it removes water, light hydrocarbons, phosphoms and silicon compounds, and heavy metals. Developed by Chemical Engineering Partners in 1997. Installations in Southern California and North Wales were planned for late 1998. 

Thus, one test (ASTM D893) covers the determination of pentane- and toluene-insoluble constituents in used lubricating oils using pentane dilution and centrifugation as the method of separation. The other test (ASTM D4055) uses pentane dilution followed by membrane filtration to remove insoluble constituents larger than 0.8 p,m. 

Energy from Used Lubricating Oils, API Pub. No. 1588, American Petroleum Institute, Washington, D.C., Oct. 1975. 

Stubbs, Overbeck and Associates, "Engineering Design of a Solvent Treatment / Distillation Used Lubrication Oil Re-Refinery," DOE /... 

ASTM D-893. Standard Test Method for Insolubles in Used Lubricating Oils. 

The corrosive activity on copper/lead bearings for typical carboxylic acids, such as decanoic, lauric, palmitic, stearic, and oleic acids, as 1 % w/w solutions in a lubricating oil base stock with excess of hard-core RMs, measured by infrared spectroscopy, supports the observation for the corrosive activity of used lubricating oils. An increase in total acidic number (TAN) is generally either an indication of contamination with acidic combustion products or the result of oil oxidation. Corrosion of bearing metals by used lubricating oils requires the presence of both acids and peroxides and probably takes place by a two-step mechanism. In the first step, the peroxide reacts with the metal to form a metal... 

D 5293 in Used Lubricating Oils and Determination of Selected Elements in Base Oils by ICP-AES Apparent Viscosity of Engine Oils Between -5 and -30 °C Using the Cold-Cracking Simulator... 

Petroleum oils often contain suspended or colloidal inorganic materials. In the case of used lubricating oils small particles of metals are present. In many cases these suspended solids are of sufficiently small particle size that efficient breakdown occurs in the flame and a simple dilution procedure may be used. However, where it is suspected that this is not the case then it is recommended that an ashing technique is used to prepare the sample. 

The determination of wear metals in used lubricating oils... 

The method is applicable to the determination of Al, Ag, Cr, Cu, Fe, Ni, Si, Sn, Mg, Pb and Zn in used lubricating oils and may also be applicable to other elements of interest. Samples are diluted with MIBK and compared with organometallic standards in MIBK. Limits of detection will range from approximately 0.1/igml-1 for elements such as Zn and Cu, approximately 1 pgml-1 for elements such as Sn and Al and greater for Si. 

Pipette 5 ml of the used lubricating oil, which has been previously agitated, into a 25 ml volumetric flask and make up to the mark with MIBK. Shake well to dissolve and homogenise. 

Hylube A process for recovering used lubricating oil. The oil is first volatilized the volatile fraction is then catalytically hydrogenated. Developed by UOP and first operated in Germany in 2000. 

Turina, N. Rapid determination of lead in used lubricating oils on thin-layer chromatograms. 1. Chromatogr. 93, 211 (1974)... 

Use Lubricating-oil additives, polymer modifiers, antioxidants, dyes. 

Use Lubricating-oil additive, hot-melt adhesives, sealing tapes, special sealants, cable insulation, polymer modifier, viscosity index improvers, films, and coatings. 

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