Poor Pump MaintenanceRepair, Rebuild, and Maintenance of Pumps
by Stephanie Eldred
Many companies ignore their pumps until they fail. And when they do fail, the main concern is how to get them up and running - fast. That's why it's so important to ask proactive questions like: How long are pumps supposed to last? How can a pump reach its best efficiency point? How can I prevent a pump from failing again? What is the proper way to repair a pump? Answering these questions can save thousands of dollars a year - maybe even a month. In short, effective pump maintenance will ensure your pumps never leave you high and dry.
The first task in repairing pumps is to note the condition of each component when disassembling the pump. Proper and complete records are one of the most commonly overlooked procedures necessary for maintaining good pump repair. Also often overlooked is the need to keep the surrounding environment clean when reassembling a pump. Bearing contamination introduced during the pump rebuild will shorten the life of the seals, the lubricant and will lead to bearing damage and bearing failure.
During a rebuild, measuring the bearings seats' diameters on the shaft and the housing with a micrometer, rather than callipers, is also advised, as improper sizes are a common cause of pump bearing failures. Ensuring that the shaft is straight is also important. The proper way to do this is to set the bearing seats on the shaft on V blocks. Then, using a dial indicator at several points on the shaft, you can determine if the shaft is bent.
When reassembling the pump bearings be sure the snap ring on the held bearing does not cover any bearing lubrication groove. Also note that the word 'top' in the casting is reassembled on the top to ensure that the bearing is not deprived of lubrication and that the labyrinth seal drain slot is down. After both the motor and pump are reattached to the bedplate (base plate) and before connecting their shafts, ensure that the two shafts are aligned. This can be done with either laser aligning equipment or with a pair of dial indicators and magnetic bases. While some feel that a straight edge will suffice when checking the alignment, this isn't advisable because a straight edge cannot detect less than 0.01".
With your reassembly completed, be sure that all bolts are tightened to the proper torque values and your pump is ready for service! To keep your newly maintained pumps working at peak levels, be sure to maintain proper bearing lubrication: If grease is used to lubricate the bearings, use either a sodium or lithium based grease with an NLGI rating of 2. If temperatures are greater than 200 °F, choose a rating of 3. Bearing grease re-lubrication intervals should be once every 3 months, under normal operating conditions. If the temperature exceeds 200 °F, the intervals should be more frequent. When it comes to ensuring your pumps run longer and more efficiently, think high quality bearings that need less bearing maintenance and increase productivity. Think training and technical service support. Think NSK.
About the author:
NSK Corporation is a world-class producer of ball and roller bearings. Established in 1916, NSK is one of the leaders in the bearing industry due to our intense commitment to engineering research, dedication to modern manufacturing processes and an obsession with quality.