We are operating a 1MW steam turbine with a plant factor of 0.95. Oil analysis is done only once in a year. A kidney type oil purification system is fixed to clean oil. Appearance of oil also good. Is the period of oil analysis is two long. What are the most important parameters to be checked. What is the acceptable regions of each parameter.

We test our turbine oil every quarter. We choose to test for water, particle count, RBOT, Viscosity, Acid Number, demulsibility, FTIR Oxidation, plus some others. These are all very important to check. Your turbine manufacturer should have some recommendations on water limits. We get very nervous once we get 500ppm. Particle counts usually run about 16/14/11. Even with an kidney filtration loop, you need to check this to make sure you are getting what you think you are. RBOT is, generically, the oxidation life of the oil. 1/2 the original value is usually the bogey point. you want to trend acid number to watch if it begins to rise. Once it does trend upwards, it can rise very quickly, indicating oxidation.