Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/359954
www.machinerylubrication.com | July - August 2014 | 37 Choosing the correct sample location can be challenging. When I'm in a plant and am asked where to install a sample port, I look for a single spot where I can gather as much useful data about the entire system. This is called the primary sampling location. At this location, the goal is to be able to draw a single sample that acts as a snapshot of the entire system. In most circulating systems, this will be on the main return line before the reservoir. By sampling from this one spot, you can check the wear debris from the rest of the system as well as the particle count to get an idea of the total contaminants in the system. Although the primary sampling location is a great place to start, it often leaves behind a lot of valuable data. This is why secondary sampling locations should be installed on most systems. The goal of a secondary loca- tion is to be able to pinpoint the cause of any fault seen on an oil analysis report. Unlike the primary port, which provides an overall look at the entire machine, secondary ports enable you to focus on individual compo- nents inside the system. Most circulating and hydraulic systems should have both a primary and secondary sampling location to ensure that any identi- fied failure mechanism can be tracked back to the component causing the problem. Not only can a secondary port be used to help determine the source of wear debris or particles, but by installing sampling ports behind filters, you can monitor how well the filter is removing parti- cles. So while the primary port may get the most use, the secondary port is invaluable once a fault has been detected. In the circulating system shown on page 36, the primary sampling port is on the main return line before the reser voir. This is a great location, as the entire system can be actively monitored from this single port. In looking through the circuit, you will see secondary sampling ports after each component in the system. This can be quite useful. For example, it was deter- mined through research and historical information that whenever the system exceeds 22 parts per million (ppm) of metal at the primary port, there is a problem with the system. The last sample taken indicated 32 ppm metal. Without secondary ports, there would be no way of knowing where the additional metal was originating. However, the engineer was wise and installed secondary ports throughout the system. By sampling at each location, it became apparent that the middle bearing was the one causing the high wear metal count. This illustration provides an excellent case in point for why secondary ports are needed. Remember, even though sampling can be a great predictive maintenance tool, a single sample port may not always be adequate for diagnosing abnormal condi- tions inside a machine. About the Author Wes Cash is a senior technical consultant with Noria Corporation. He is a mechanical engineer who holds a Machine Lubrication Technician (MLT) Level II certification and a Machine Lubricant Analyst (ML A) Level III certification through the International Council for Machinery Lubrication (ICML). Contact Wes at wcash@noria.com. Even though sampling can be a great predictive maintenance tool, a single sample port may not always be adequate for diagnosing abnormal conditions inside a machine. 34% of lubrication professionals have secondary sampling ports installed on equip- ment in their plant, based on a recent survey at machinerylubrication.com