The discussion of maintenance, when related to pumping equipment, involves many different and varying opinions. The correct opinions will resolve themselves into simple basic engineering fundamentals. To reduce the cost of maintenance on pumping equipment, the previous topics of purchasing and installation can be used as guides to help determine existing problems in those areas and what should be done to correct them. If problems in those areas exist, proper maintenance and repairs alone will not solve them.
When repairing a pump, it is always good practice to follow instructions in the manufacturer's maintenance manual. There are, however, some basic rules of thumb that can help in the process of pump repair.
Determine the "root cause" of the problem. For example, a bearing failure may not have been because the bearing has reached the end of its expected life. It may have failed, and most probably did, because of some other reason. That reason could be a multitude of things, from lack of lubrication to improper installation. If this is the case, the bearing failure is only a symptom of the real problem. To prevent future failures, the root cause of the problem must be determined and corrected.
Document your repairs. This can help identify problem pumps and aid in diagnosing pump failures. By documenting pump repairs, a pump requiring frequent repairs can more easily be identified. When identified, a "problem" pump can be flagged as one needing closer inspection of the installation, piping, repair procedures and operation. The closer inspection will assist in determining the "root cause" of the failures (see above).
One lubricant may not be satisfactory for all applications. Always refer to the lubricating instructions in the manufacturer's maintenance manual. If your application has some unique circumstances, contact your local distributor or the pump manufacturer for additional assistance. Your lubricant supplier may also be a good source for recommendations on the proper lubricant to use.
Before disassembling the pump, inspect the lubricant. If it appears to be contaminated, have it analyzed to determine what type of contaminants are causing the problems. Once the type of contamination has been determined, take corrective action to prevent its reoccurrence.
Don't over-lubricate pumps. Over-lubrication can be as damaging as under-lubrication.
Dimensional checks should be performed on the pump during disassembly and assembly. Document your measurements for future reference and to determine if parts are within the manufacturer's standard limits. This can be extremely important to the life of bearings and mechanical seals.
Set the proper operating clearances. Many pumps have operating clearances that must be set at different tolerances for various operating conditions. Determine the clearances required for your application. This can often be determined from the instructions in the manufacturers maintenance manual. If the manufacturer's maintenance manual does not provide you with the necessary information. contact the distributor or manufacturer for assistance.
The illustrations on the following pages can be used to help establish some general inspections and checks of pumps during repair and assembly.