Machinery Lubrication magazine published by Noria Corporation
Issue link: http://www.e-digitaleditions.com/i/290460
6 | March - April 2014 | www.machinerylubrication.com JeremY wrIGht | NorIA CorPorAtIoN o i l A n a l y s i s From the FIeld Is oIl Analysis a wAste of tIme? How confident are you in your oil analysis data? Are you using it to make critical decisions about machine mainte- nance, production or shutdown schedules and machine rebuilds? How can you be sure you are getting the best information to make these decisions? As I travel around the world helping companies design, imple- ment and improve their oil analysis programs, I can't help but question the validity of their past results. There are several funda- mentals that must be performed correctly to get the maximum value from an oil analysis program. These concepts are fairly simple once you consider the effects each one could potentially have on the overall program. Selecting Machines At what point do you deem an asset important enough to the company's mission to warrant spending extra time, money and energy to ensure the reliability of that asset? When I am designing an oil analysis program, I use two main criteria for determining which machines require sampling: sump size and criticality. These two factors are somewhat related. Imagine a machine that is not critical to the plant's process yet holds several thousand gallons of fluid. You would want to conduct testing on this oil to ensure you are getting the most useful life from it and not throwing it away prematurely based on a calendar change-out (condition-based vs. interval-based change). Likewise, if a machine is critical but holds very little oil, you would also sample the oil even if it meant taking a large percentage of the oil from the housing and having to top-up. This sample is not to test the oil quality, age or properties but to obtain information about the machine's health. Sampling Frequency Sampling frequency is influenced by several variables, including the economic penalty of failure, fluid environment severity, machine age, oil age and target tightness. Economic Penalty of Failure The higher the penalty of failure, the more often a sample should be taken. The penalty of failure must take into account the cost of downtime, the cost of repair or rebuild, the overall interruption to business and the impact on product quality or output. Fluid Environment Severity Fluid environment severity includes more than just the opportu- nity for particulate, process chemical and moisture contamination but also takes into account the demands placed on the lubricant by the machine. This includes the pressure, speed and load as well as the duty cycle. The greater the risk of lubricant damage, the more frequent the sampling. Machine Age The likelihood of machine failure can be tied to machine age. A machine has the likeliest possibility of failure when it is brand new