Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/359954
36 | July - August 2014 | www.machinerylubrication.com The starting point of any great oil analysis program begins with obtaining representative samples. The goal of sampling is to maximize data density while minimizing data disturbance. You maximize data density by sampling in the right location with the right equipment at the right time. Often, the right location is a "live zone" within the machine where oil is flowing in a turbulent manner. This allows you to capture a sample containing all the useful information needed for trending without losing any data via particle fly-by or settling. The right equipment includes the use of minimess sampling valves, vacuum sampling pumps, disposable tubing and other accessories for taking samples as cleanly as possible. Depending on the criti- cality of the machine or how poorly it is operating, the sampling frequency may be very long (every six months) or very short (every two weeks). Drawing consistent samples helps to trend wear debris, contamination levels and lubricant health. Minimizing data disturbance depends on how well the sample extraction process is designed. A common mistake is failing to flush the sample equipment as part of the procedure for drawing a sample. If you are using disposable tubing and a vacuum sampling device, the tubing must be flushed to get a true representative sample. Flushing between five to 10 times the dead volume from all sampling equipment is recom- mended. This ensures that any contaminants inside the tubing are cleared out and that the sample will be representa- tive of the conditions inside the machine. Using the proper cleanliness specifica- tions on the sample bottles will also help reduce the signal-to-noise ratio that can skew particle counting efforts. If you put oil into a dirty sample bottle, the results will show that the oil in the system is dirty when that isn't necessarily true. Make certain that sample bottles are cleaned to the specifica- tions required to hit your target cleanliness goals. If you receive sample bottles from a laboratory, call them and ask what quali- ty-control process they have in place for the bottles and if they are certified to a specific cleanliness standard. IN the treNChes l u b r i c a n t s a m p l i n g Primary vs. Secondary Sampling Ports whY oNe oIl sampling PoINt Isn't AlwAYs enough wes CAsh NorIA CorPorAtIoN 17 ppm 62 ppm 17 ppm +5 +50 +5 12 ppm +2 10 ppm 100 ppm 5 ppm 1 ppm 10 ppm 32 ppm P S S S S S S S Breather Off-line Filtration P Primary Sampling Port S Secondary Sampling Port Primary samPling Ports/valvEs should be properly located and installed at the factory, and provide an overall look at the entire machine. sEcondary samPling Ports/valvEs should be installed on many circulating systems and enable you to focus on individual components inside a system. Examples of primary and secondary sampling port locations in a circulating oil system