Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/985736
34 | May - June 2018 | www . machinerylubrication.com LESSONS IN LUBRICATION A Little History Some of the first known filters were created to remove unwanted contaminants from water. is process was pioneered by the Romans, but it has also been cited as having other origins. e word "filter" actually comes from the Latin word "filtrum" or "feltrum," which is related to felt or compressed wool, providing a means to filter contaminants when water passes through it. e development of filters for oil cleanliness did not occur until the early 1900s through the progression of crude oil refining and the automobile industry. Water-induced Filter Failures A filtration system generally is sized and configured to handle the expected types and amounts of contaminants to which the system will be exposed. It is also important to select components for the filtration system that will allow for infrequent filter maintenance. The differential pressure gauge should change gradually as the filter element becomes saturated. After several cycles of normal filter changes, the maintenance schedule will become predictable. However, when unexpected water is exposed to the system, it can clog the filter and cause a drastic change in the differ- ential pressure, putting sudden strain on the filter element. If this continues for days or weeks, the element can form a bypass gap in the damaged media, enabling oil to flow through unfiltered. So, while these types of filters can absorb a certain amount of undesirable water, if water-saturated filters are ignored for long periods of time, the filtration system will become compromised. Another way water can damage filters is through oxidation. Small amounts of water in oil, typically in the dissolved state, are not unusual and in some cases unavoidable. If the water remains in small quantities, Filterability vs. Percent Water and Membrane Pore Size 2 20 40 60 80 100 FILTRATION VOLUME, mL TIME, min. 120 140 0% H 2 O 0% H 2 O 0.1% H 2 O 0.1% H 2 O 5 μm 1.2 μm 4 6 8 10 12 14 B-83-701 Water Bath 47 mm 3.0 Test Membrane Sample Non-Aerating Stirrer Peristaltic Pump 20 mL/min. Graduated Receiver Water Bath Controlled to 62.5°C Filterability Factor = Volume of filtered fluid (ml) Area of membrane (cm 2 ) Terminal ∆P = 1.7 Bar μm