Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1487844
Among the most common, we find inductive, capacitive, optical and ultrasonic sensors. Real-time sensing in critical machinery fluids brings the benefit of timely detection of a problem associated with lubrication, contam- ination or operational conditions. e timely detection allows for prompt actions, such as planned inspection, validation through other predictive techniques or starting a filtration or water removal process. What follows is a summary of current lubricant cleanliness moni- toring technologies. During the past two decades, there have been different developments and improvements in the principles of oil cleanliness devices and sensors. Portability, accuracy, interface experi- ence and on-line capacities provide the lubricant teams with an easier-to-use and flexible tool. Automatic particle counters based on light extinction are still the most common method used by the industry for particle contamination analysis. (Fig 1) As a particle passes through a light beam, the light intensity received by a photo-detector is reduced in proportion to the size of the particle. Special care should be taken to mitigate inaccuracies due to air and water bubbles, which are very common in lubrication circuits of the machinery. Mesh blockage devices are an effective alternative to light extinction, especially in conditions where the fluid is opaque or where free water or air bubbles are present. (Fig 2) Mesh blockage devices determine particulate contamination levels by passing a specified flow of sample fluid through a series of calibrated mesh screens in a specified sequence. Pressure drop build-up (or flow degradation) is depen- dent on particulate contamination levels. e mesh is cleaned by backflushing. New technologies are emerging from the development of digital high-resolution image processing. (Fig 3) In this type of cutting-edge sensor, the particle passes between a light and a lens, and an integrated Complimentary Metal Oxide Semiconductor (CMOS) Sensor and processor acquires and automatically processes microscopic images of fluid contamination, detecting, quantifying and classifying the particles by size. en, computing logarithms and artificial intelligence transform the images obtained into technical data. It is possible to get the on-line cleanliness ISO4406 code with portable monitors or sensors connected to the machines. Depending on the type of application and the character- istics of the fluid, a particle monitor can be connected to a representative point of the system and display the data through a local screen, printer, USB memory or by extracting the data through a cable. In many cases, for critical machines, a sensor connected directly to a live turbulent pipe allows monitoring of the condition of contamination and wear downstream of the mechanical components, thus obtaining real-time readings on a computer or smart device. e advances in air and water bubble detec- tion should not be overlooked to avoid false readings, especially when there are low pres- sures, like in cases when sampling is needed in return point lines and external filter carts. Particularly interesting are the innovations to permanently quantify the lubricant color in Table 1. On-line Oil Cleanliness Technologies. RAMGUZ Figure 1. Light Extinction Principle. Pall Corporation Figure 2. Mesh Blockage Principle. Pall Corporation www.machinerylubrication.com | November - December 2022 | 15 ML ML ML