A November 2017 article by Pumps and Systems points out that many industrial plant maintenance crews have become experts at corrective pump maintenance procedures. Replacing seals and bearings or the entire pump itself often becomes routine for these workers because of sheer repetition.
Plant maintenance teams need to be able to monitor flow rate, temperatures, and pressures and know how to interpret that data to prevent pump problems before they occur. The lack of adequate sensors on many pumps prevents any detection of the potential pump hazards in the system. Even when information is available from sensors, lack of training could cause a failure to recognize a problem in time to take action.
Related Blog: Understanding How to Measure a Pump’s Performance
The Ideal Pump?
The "ideal pump" is carefully selected and matched to anticipated operational demands by engineers for the initial plant design may not continue to be the ideal pump for changing conditions in an aging system. Working environments are always dynamic as wear and tear, or corrosion all take their toll on pumps, control valves, and piping.
Years down the line vibration, cavitation, high-pressure spikes, and overheated motors cause too many pumps to "run to failure". Pump failures can cause spills, fire and chemical hazards, not to mention the potential to shut down the entire plant. If the worst case "run to failure" scenario does not occur, pumps still running under these conditions cause excessive maintenance and use way too much energy.
Fortunately, instrumentation and procedures for plant maintenance personnel can be implemented to optimize pump efficiency and save both time and money by extending the service life of the pump without costly recurring maintenance and shutdowns.
Pump Instrumentation and Software
In his 2018 article at Pumps and Systems, pump expert Jim Elsey notes that 90% of pump problems occur on the suction side of the pump. While most pumps have a flow rate meter to monitor discharge rate, many lack any sensing device to monitor the suction side where most pump problems begin.
Differential Pressure Devices (DP)
EdP transmitters are perfect for monitoring differential pressures of a pump. They monitor suction and discharge pressures, and newer devices can also monitor pump temperature. Too high or low suction or discharge pressures can cause a host of problems which can be avoided with a DP device including:
- loss of flow
- mechanical failure
- vibration issues
- excessive noise
- bearing and sealing wear
Smart Flow Meters and NPSH (Net Positive Suction Head)
Cavitation is caused when the net positive suction head (NPSH) available is less than the NPSH required. NPSH must always be equal to or greater than rated for the pump plus a generous safety margin. NPSH can be affected by changes in supply tank levels or pressures in front of the pump as well as changes to flow rate.
Smart flow meters can monitor and diagnose these conditions having the potential to damage the pump including:
- entrained air
- vibration (possibly caused by pump cavitation)
- a coating
- unsuitable media
Pump Analysis Software
DP devices and smart flow meters can route data to the control systems and pump analysis software. This software compares the monitored pump curve to the performance curve as it should be. The Department of Energy provides The Pumping System Assessment Tool (PSAT). This free online software helps industrial users evaluate the efficiency of their pumping system operations by using data from the Hydraulic Institute and the MotorMaster database.
Walkaround Management and Training
Even with all the enhancements of technology we've discussed above, there still is no substitute for the frequent walkaround inspection. As Jim Elsey points out in his article, "If you do not manage the system, it will manage you."
System knowledge is crucial since we must know how the system is designed to operate in order to know when something has gone wrong. Once pumps or other equipment fail it's too late and we are reduced to "managing from the rear-view mirror." Proper training ensures that engineering and maintenance teams know how to interpret the data provided by DP and smart flow meters.
With rag, flashlight, and camera in hand, a thorough walkaround can uncover wear, corrosion, and unauthorized alterations in time to take preventative measures. Reviewing logs for changes in flow rates and pressures can reveal long-term trends. Proper training ensures that engineering and maintenance teams know how to interpret the data provided by DP and smart flow meters.
At Mader Electric we're committed to keeping your industrial motor, pump, and control systems operating at peak efficiency. We've been keeping businesses running since 1903, so you can count on our expertise for all of your industrial electric needs.