Rock Products

SEP 2018

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Page 42 of 61 ROCK products • September 2018 • 41 EQUIPMENT & TECHNOLOGY PUMPS & MOTORS When you install a new submersible pump, you expect con- sistent operation that will last for several years. But, chances are, the submersible pump will be performing in rugged con- ditions that can eventually take a toll on a pump. Proper preventive maintenance can help prolong the service life of your submersible pump, allowing smooth operation at optimal levels. Upon installation of your new submersible pump, your tech- nician will test it and provide a start-up report. The report compares the data sheet specifications to your actual oper- ational performance at the time of pump startup. If you experience performance changes with your pump over time, you can refer back to the start-up report and compare the current measured performance data with the original per- formance data. Routine preventive maintenance inspections can help address possible issues before they become major or even catastrophic problems. Preventative maintenance also helps you troubleshoot or identify root causes of issues and helps drive corrective action to resolve and prevent these events from occurring in the future. There are four key areas to be sure to include in your maintenance checklist. 1. Electrical Check Your submersible pump is powered by electricity. Moni- toring the electrical use can help identify a problem with your pump's operation. The amperage load is the amount of current (amps) the pump motor draws from the electrical system. With submersible centrifugal pumps, the increase in current flow (measured in amperage) corresponds to an increase in flow or solids loading. The amp draw will be less when there is no flow, while maximum flow should increase the amperage draw to the rated amperage or Full Load Amp draw (FLA) found on the product nameplate and data sheet specifications. Most sub- mersible pump motors have a service factor that will allow safe operation to a slightly higher level as needed for higher pump loading. Two critical electrical attributes that should always be mea- sured on a submersible pump electric motor are the input voltage and the output current draw. The input voltage should match the nameplate specifications by +/- 10 percent. The voltage measured during the initial starting should not drop by more than 5 percent of the measured line voltage with no loading. The voltage supplied to each leg of a three- phase motor design should show no more than a 2 percent variation. The measured amp draw of the motor should not see a vari- ation more than 5 percent on each leg and should be within the nameplate specifications of the pump. As part of a good preventative maintenance program, the voltage and amper- age draw are periodically measured and compared to the original start-up data. 2. Alarm Monitoring A submersible pumping system can be setup with monitoring devices that will alarm if a potential failure threshold has been reached. One of the most important criteria to monitor on a submersible pump is the mechanical seal chamber. Many submersible pumps incorporate a seal failure control circuit in the controls that works in conjunction with a seal minder Inspection Guidelines for Maximum Pump Life and Output Performance

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