Machinery Lubrication

Machinery Lubrication Jan Feb 2014

Machinery Lubrication magazine published by Noria Corporation

Issue link:

Contents of this Issue


Page 44 of 79

40 | January - February 2014 | BeNNett FItCh | NorIA CorPorAtIoN The decision to perform oil sampling can be difficult. You must consider whether to spend the extra time to take a sample and the extra money for oil analysis. Once the decision is made, it is critical to understand how to maximize the data's value and minimize any disturbance that could render the sample useless. No matter how much attention is paid to an oil sample or how effective the laboratory equipment is, the results are meaningless if the sample is not representative of the system's fluid. While this may appear to be common sense, more thought is usually given to the lab or the oil analysis results than the techniques and equip- ment used in the sampling process. This article is the sixth installment of a series of "anatomy" lessons within Machinery Lubrication. In this issue, the importance of oil sample bottles in obtaining a representative sample will be discussed. Subse- quent articles will address proper sampling equipment, selecting a sampling valve and choosing the best sampling location. It has often been said that particles too small to be seen by the unaided eye are the most destructive in three-body abrasive wear. These particles, which are typically in the 5- to 15-micron range, have the capability of getting trapped between surface gaps rather than shooting through the gap or being held outside the gap. For this reason, particle contamination analysis commonly presents data as three range numbers for particles greater than 4, 6 and 14 microns. Given that these "invisible" particles are substantial, it is imper- ative to ensure that they are not present within the sample bottle prior to a sample being obtained. This means that drawing a sample into a washed-out soda bottle will not be good enough. Even a sample bottle purchased with the lid and bottle in separate packages will not be sufficient. Sample Bottle Cleanliness Rather than using the closest "bottle" you can find or purchasing the cheapest sample bottles on the market, consider the cleanliness levels of sample bottles established specifically for this purpose. The required sample bottle cleanliness will be based on the impor- tance of the sample being taken and the sensitivity of the tests being conducted. One method of classifying sample bottle cleanliness provides three categories for specifying the range of particles in a bottle. "Clean" oil sample bottles are defined as having less than 100 parti- cles greater than 10 microns per milliliter of fluid. This cleanliness level is the most common and least expensive. "Superclean" oil sample bottles can be defined as having less than 10 particles greater than 10 microns per milliliter of fluid. "Ultraclean" oil sample bottles are defined as having less than 1 particle greater than 10 microns per milliliter of fluid. ISO 3722 also describes a certification procedure based on randomized testing for cleanliness. ANAtomy of an oIl sAmPle: Part 1 — sample Bottles l u b r i c a n t s a m p l i n g lessoNs IN lUBrICAtIoN Sample bottle cleanliness can be categorized as clean, superclean or ultraclean. Ultraclean Superclean Clean These images show general headspace or ullage recommendations.

Articles in this issue

Links on this page

Archives of this issue

view archives of Machinery Lubrication - Machinery Lubrication Jan Feb 2014