Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/572212
28 September - October 2015 | www.machinerylubrication.com account. A variety of factors play a role here, including the engine manufacturer, the engine type, the type of fuel used, the oil volume, the motor oil type, the service life of the motor oil, and any top-up quantities (makeup oil). The operating conditions can also vary markedly from one situation to the next. After all, the engine of a heavy construction machine oper- ates under different conditions than the same engine of a truck traveling long distances on a highway at uniform speed. However, all of these engines have one thing in common: their motor oil contains a lot of valuable information about the oil itself as well as the state of the engine. For example, the microscopic particles suspended in the oil provide an indication of the amount of wear of the corresponding parts or components. Elements such as sodium, potassium or silicon indicate contamination by road salt, hard water, glycol antifreeze or dust. Comparing the amount of organometallic additive elements (such as calcium, magnesium, phosphorus, zinc, sulfur or boron) in the used oil to fresh oil provides an indication of changes to the oil, such as additive depletion or possibly the mixing of different types of oils. Inductively coupled plasma (ICP) elemental analysis can be used to determine more than 30 different elements in motor oils. In addition to the presence of the elements, atomic emis- sion spectroscopy (AES) by ICP can be used to determine the concentrations of the elements. Laboratories routinely determine the following elements and values as part of motor oil testing and list them in the lab report: iron, chromium, tin, aluminum, nickel, copper, lead, calcium, magnesium, boron, zinc, phosphorus, barium, molyb- denum, sulfur, silicon, sodium and potassium. In some cases, other elements are also determined, such as silver, vana- dium, tungsten or ceramic elements like cerium and ber yllium, which are rarely present in motor oils. They are only listed in the lab report if they are actually proven to be present or if the customer specifically requests this. Tables 1-3 show the possible causes for the presence of the elements found in oil, i.e., whether they are related to contaminants, wear or additives. Various factors must be taken into account when interpreting a lab report and the values of the elements found in the oil. Naturally, it is not sufficient to simply report the elements and OIL ANALYSIS ELEMENT UPPER WARNING LEVEL ORIGIN Silicon (Si) 15–30 Up to 15 in fresh oil Intake air dust, anti-foam additive in motor oil, worn seals containing silicone, residues of silicone greases (also in oil sampling syringes), worn aluminum alloys (aluminum engines) Potassium (K) 2–30 Additive in aqueous media such as glycol antifreeze or cooling water; mineral salt in road salt or tap water Sodium (Na) 5–30 Up to 800 in fresh oil Additive in glycol antifreeze or cooling water; road salt, tap water, wastewater or salty air; additive components in some motor oils as a substitute for calcium or magnesium compounds; thickener in lubricating greases Lithium (Li) 2–10 Constituent of multi-purpose greases (thickener); indication of contamination by grease or assembly pastes Antimony (Sb) 1–3 Present in some lubricating greases as an EP additive in the form of antimony oxide; in connection with lead or tin in bearing alloys of plain bearings Silver (Ag) 1–3 Silver-plated running surfaces of highly loaded plain bear- ings, such as in locomotive engines; silver solder residues; silver is attacked by additive systems containing zinc Tungsten (W) 1–2 Rare in engine construction; alloy constituent for increasing hardness and corrosion resistance Titanium (Ti) 1–3 Oil level indicator (float); alloy constituent in springs and valves; from ceramic components; as white titanium oxide in plastics and paints; marker additive in motor oils Vanadium (V) 1–3 As a constituent of chrome-vanadium steel alloys in valves and valve springs; like nickel, it is a constituent of petroleum; blow-by product when ship engines are operated with heavy oil fuels Beryllium (Be) 1–3 Cube valves and valve seats; sintered bearings, constituents of sintered ceramic components or in jet engine oils; prohibited in F-1 engines Cadmium (Cd) 1–3 Components of plain bearings exposed to corrosion; sometimes also deep red pigments in plastics and paints Cobalt (Co) 1–3 Possibly from components of turbines or from roller bearing alloys in connection with iron Manganese (Mn) 1–3 Alloying element, usually with iron; steel used in valves, roller bearings, gears or shafts; contaminant in manganese mines (with Si); very rarely additives containing manganese Tantalum (Ta) Only found in oil as a constituent of ceramic components Cerium (Ce) Only found in oil as a constituent of ceramic components Zirconium (Zr) Only found in oil as a constituent of ceramic components Table 2. Contaminants