The centrifugal pump is a critical part of your water truck build. When it’s operating at peak efficiency, so are you… but inevitably that’s not always going to be the case. Water pump failure can cost you time, money, and potentially bring your operation to a halt. What should you focus on to prevent it? Are there common points to look out for when troubleshooting an issue with your pump?
The short answer is the Pump Shaft, one of the main points of stress in any centrifugal pump system. There are many factors that can lead to a broken shaft. Continue reading below to learn about the most common issues that can contribute to pump shaft damage, and steps you can take to reduce the probability of failure.
Manufacturing Process & Material Flaws
While it’s not outside the realm of possibility that flaws in material and manufacturing can occur, only a small percentage of failures are due to manufacturing flaws. The most common root cause of system damage is improper operating conditions putting undue strain on the pump and its components. This is good news because it means that you are in control and can take steps to reduce the risk to your investment.
Misalignment & Water Pump Failure
One of the most common causes of pump shaft damage is misalignment of the PTO and the pump. A frequent assumption when installing a new pump is that the pump and the PTO should be perfectly aligned with each other. This may make sense in theory, but in practice it can be a source of strain and eventual failure of your system. Proper installation requires a slight offset between the angled PTO and the pump. The difference in position is then compensated for by the drive-shaft and U-joints used to connect the PTO to the pump.
Vibration is never good for any mechanical system and can put unnecessary strain on your entire pump. Vibration is most commonly caused by cavitation, running at excessive RPM, impeller imbalance due to blunt force, or operating outside the pump’s optimal efficiency range. Continuing to run a vibrating pump eventually leads to pump bearing wear, allowing the shaft to shift laterally from its mounting position causing it to flex and eventually fail.
When operating a fluid dispersal system, there is risk of shock to that system from hydraulic forces exerted by the fluid being pumped. Imagine dropping a stone in a pond – the force applied by the stone sends shock-waves far away from the initial point of impact. This same force can be exerted on your system by a sudden stop in fluid movement, called a Water Hammer. When valves are shut off at high RPM, a shock-wave can be sent back down the pipes to the pump which can exert shearing forces on your shaft and potentially lead to a bend or complete breakage of the pump shaft. You can remedy this by lowering the RPM or disengaging the PTO before shutting off the valves. To further insure against damage from a Water Hammer, you can install a relief valve to vent the excess pressure and prevent it from reaching your pump.
These are only some of the most common factors that can lead to water pump failure, download our Centrifugal Pump Guide for more information on proper maintenance practices. With adequate care and mindful operation, the life of your pump and shaft will be long and fruitful.