Machinery Lubrication India Jan Feb 14 10 | Page 30

Sampling Procedures during an Oil Drain level in the gearbox from the sight gauge Always use clean, lubricant-compatible sample will be used to determine bulk plastic or glass sample bottles and or from direct measurements. This oil properties that are more caps, and keep all sampling equipment representative of the in-service oil thoroughly clean. Prior to sampling, fill properties. out the label and attach it to the sample bottle. Be sure to record the sample point and the date. Third Oil Sample Take the third oil sample near the end of the drain. This sample might capture A lubricant contaminated with water produced corrosion on this helical gear. be determined. This method has an outstanding sensitivity for larger particles. tells the same story as particle counting a hydraulic system or pump application — that of cleanliness. When establishing an oil analysis program that is less dense contaminant fluids. draining and sampling includes: • Clean containers for holding the drain oil When all the calculations and tests are completed, form one or more • A wire-mesh screen Particle counting in industrial gearboxes in The equipment needed for proper proactive in controlling contamination, particle counting is a vital component to the routine test slate. hypotheses for the probable cause of • Four or more clean laboratory failure and then determine if the bottles (clear plastic) for taking samples • A large bottle for capturing excess water First Oil Sample Drain the oil through the screen to capture any large wear debris or fracture fragments that might be entrained in the drain oil. Take the first oil sample at the start of the drain. Be prepared to capture any free water that may have settled in the gearbox. If there is a large quantity of water, fill a sample bottle and then capture the remaining water in the large bottle. Once the water stops flowing, take a sample of the oil. This is an example of point-surfaceorigin (PSO) macropitting caused by tip-to-root interference. Second Oil Sample Take the second oil sample near the middle of the drain. Estimate the oil Is the Oil Representative of the Service Oil? In this example, abrasion and scuffing have been caused by tip-to-root interference. evidence supports or disproves the hypotheses. While similar procedures apply to any failure analysis, the specific approach can vary depending on the nature of the failure and time constraints. So whether you perform tests on-site or send oil samples to a laboratory for further analysis, be sure to select the If the oil appears very clean, it might appropriate test to help you correctly have been changed after the failure determine the probable cause of a occurred. Therefore, check maintenance failed gearbox. records and interview maintenance About the Author personnel to determine whether the oil is representative of the oil that was in service when the failure took place. A lubricant contaminated by sand resulted in abrasion on this spur pinion. 28| January-February 2014 | www.machinerylubricationindia.com Robert Errichello is a gear consultant with GearTech. Contact him at [email protected].