Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/985736
ML most filters will not have any significant consequences. However, if the water amount rises beyond the saturation point, the negative effects on the lubricant and equipment will increase, impacting the filter's performance. Water's reactive nature also promotes oxidation reactions with the lubricant's molecular structures. As oxidation occurs, water reacts with hydrocarbons to form free radicals and oxygenated compounds. ese new products in the lubricant expose the equipment's lubrication zones to the detrimental effects of organic acids and high-molecular-weight polymeric products. In other words, sludge, tar, varnish, slimes and other resins will form, wreaking havoc anywhere the oil flows. One of the places where the oil will flow is to the filter, where these gummy and sticky substances will quickly saturate the element. In addition, water encourages the growth of microbial organisms. For example, bacterial growth can cause the formation of sulfuric acid, which can become corrosive in the oil and to machine surfaces. When this type of growth goes unnoticed and uncontrolled, it can result in premature lubricant degradation, corrosive wear and shorter filter life. Colder operating temperatures can also create challenges with all aspects of lubrica- tion and equipment operation. In regard to filters, not only is the oil more viscous, but water at subfreezing temperatures in a lubri- cation system can lead to alarming issues. Water droplets will turn into ice crystals, particularly when water is heavily entrained. ese crystals will form a new type of solid contaminant that can lodge in the filter media, causing a rapid decline in the filter's performance. With turbulence and changing temperatures, permanent damage to the filter can also occur as the crystals fluctuate in size and position. In some cases, the filter may rupture when flow is obstructed. Lubricant Filterability Just as contaminants and operating conditions can disrupt or damage a filter, certain oil properties can also cause challenges in the oil's ability to be filtered. Filter- ability is the term used to describe the ease at which oil can be filtered, even in the presence of external contaminants such as water. Many oils are tested for their filterability using the procedure specified by ISO 13357-1:2017. is procedure is based on the premise that lubricating oils may become unfilterable for reasons other than viscosity. Since water is known to impair filtration, the first part of the procedure was designed to establish "a method for assessing the filterability of SAMPLE NO. FILTERABILITY FACTOR FILTERABILITY INDEX 0% H2O 1% H2O 2% H2O 0% H2O 1% H2O 2% H2O Hydraulic Fluids A 31.9 21.4 13.9 B 45.2 66.6 62.1 C 104.2 104.2 104.2 D 8.8. 8.9 10.4 E 47.4 52.1 43.2 F 2.1 0.0 0.0 Automatic Transmission Fluids G 9.4 5.5 2.6 H 104.2 51 36.5 I 5.7 3.6 2.5 Engine Lube Oils J 14.6 21.9 22.9 K 8.9 3.1 2.6 Fire-Resistant Fluids Water-Oil Emulsion A 0.17 0.52 B 3.7 5.6 6.25 10.2 25.8 28.3 C 0.1 0.26 D 0.02 0.05 E 0.0 0.0 0.0 0.0 0.0 0.0 Water Glycol F 48.9 57.3 62.5 58.6 49.8 89.3 G 104.2 119.8 H 104.2 65.1 I 104.2 90.2 J 104.2 93.8 91.2 51.6 46.6 48.0 Synthetic Fluid K 4.2 14.5 16.3 14.0 18.1 19.6 L 104.2 104.2 104.2 576.9 473.6 385.9 M 21.98 25.8 38.5 19.3 13.6 17.1 N 104.2 104.2 104.2 80.2 51.3 34.97 O 20.8 20.1 19.2 26.0 10.2 11.4 P 21.7 34.4 39.2 19.7 15.6 37.3 Fluid filterability spectrum (Ref. Fluid Contamination Control) www . machinerylubrication.com | May - June 2018 | 35