833104 5 Mercury GEAR, Driven

Corrosive Gaseous Fuels
Corrosive gases may contain high levels of sulfur compounds, halide compounds, and ammonia compounds. Your Cat dealer has specific guidelines for these corrosive compounds. Consult your Cat dealer regarding the best methods for measuring and controlling these compounds in your gaseous fuel supply.When these corrosive compounds are present in gaseous fuels, perform additional tests on used gas engine oils. These additional tests may also be used if an oil related issue cannot be resolved through the standard set of S O S Services tests.Some gaseous fuels may contain significant amounts of corrosive compounds. These corrosive compounds can form highly corrosive acids in the engine oil. The S O S Services tests for Oxidation, Nitration, and Viscosity will indicate that these acids have degraded the oil. In many applications, these tests are sufficient to alert the customer regarding problems with oil deterioration. However, TAN and TBN are recommended in addition to the standard S O S Services tests.There are two ASTM test methods for the TBN test: "D2896" and "D4739". The "D2896" method is run to establish the TBN of new oils. "D2896" is best used when sulfur compounds are present. "D2896" does not always show a consistent decrease in base number with oil deterioration. The "D4739" method is more effective when monitoring the deterioration of used engine oils. "D4739" usually shows a consistent decrease in base number, as an oil deteriorates. "D4739" responds to sulfuric acids and formic acids. A trained analyst, in the S O S Services program, should be utilized to interpret TBN results. The S O S analyst understands the correlation of TBN results to: corrosive wear, oil oxidation, and oil nitration.Another test that is sometimes used to evaluate oil condition is Total Acid Number (TAN). The preferred method for TAN testing is ASTM "D664". The TAN test is a measure of the acids that are formed in the used oil. TAN values will increase as oil deteriorates. Like the TBN tests, the TAN test has limitations. Sometimes, the TAN test does not measure all of the acids that are present in the oil. A trained analyst, in the S O S Services program, should be utilized to interpret TAN results. The S O S analyst understands the correlation of TAN results to: corrosive wear, oil oxidation, and oil nitration.Because of the specialized nature, all S O S Services laboratories may not be equipped to run TBN and TAN tests. If your S O S Services lab cannot run these tests, your dealership can make arrangements to run these tests at another laboratory.TAN and TBN results combined with the normal S O S data can be helpful in trending the oil condition.Note: S O S Services oil analysis for all bio gas sites and any site that may have corrosive compounds in the gaseous fuel should include: Oxidation, Nitration, Viscosity, Wear Metal, TAN, and TBN test results.Silicon Containing Gases
Cat gas engines that operate on landfill gases may experience high levels of silicon in the lubricating oil. One possible source of this silicon is from a family of gases called siloxanes. Siloxanes are organic compounds composed of silicon, oxygen, and methyl groups. After combustion, this type of silicon enters the oil through the blow-by gasses and the oil film on the cylinder liners.The silicon compounds from siloxane gases are much less abrasive than silicon compounds found in dirt. Gas engines can operate with silicon levels up to 125 ppm when the source of the silicon is siloxane gases. A trained analyst should be utilized to determine the safe level of silicon and the source of the silicon. Elevated silicon levels caused by dirt entry will severely damage internal engine components. Refer to the Special Publication, LEBW4977, "Gaseous Fuels - Application and Installation Guide" for more information on siloxane gases and other contaminants.S O S Services Oil Analysis Guidelines
A trained analyst, at your Cat dealership, interprets the results of these oil analysis tests. S O S Services oil interpretation is built on a system of trend analysis, correlating data, and historical guidelines. The S O S Services analyst understands the interactions of each test. Analysts use this information to make an accurate interpretation of the oil analysis test results.The table below lists the guidelines that are used to evaluate used engine oils.
Table 1
Oil Analysis Guidelines for non-corrosive(1), low silicon(1), gaseous fuels
Test Parameter S O S Services Oil Analysis General Oil Analysis
Water 0.5% Maximum 0.5% Maximum
Glycol 0.1% Maximum 0.1% Maximum
Viscosity "ASTM D445", at 100° C (212° F) +3 centistoke (cSt) change from new oil viscosity +3 centistoke (cSt) change from new oil viscosity
Elemental Analysis Cat statistical norms and trend analysis(2) Trend Analysis and statistical limits established by the testing laboratory(3)
Oxidation Caterpillar SOS uses the UFM method for measuring Oxidation. The general guideline is 30 UFM for condemning the oil.(4) 0.25 absorbance / cm-1 based on "ASTM D7418" differential scan method, and trend analysis
Nitration Cat guidelines and trend analysis 0.25 absorbance / cm-1 based on "ASTM D7418" differential scan method, and trend analysis
Additional Oil Analysis Guidelines for corrosive(1), high silicon(1), gaseous fuels
Total Acid Number (TAN) by "ASTM D664" 3.0 maximum or 2.0 greater TAN than the new oil 3.0 maximum or 2.0 greater TAN than the new oil
Total Base Number (TBN) by "ASTM D2896" 50% of new oil TBN 50% of new oil TBN