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24-11-2022
How to extend the life of your groundwater pump
Once you have installed your pump in the ground, you want it to last as long as possible, as repairs can be inconvenient and costly. There are few things you can do to ensure your pump operates for as long as possible.
Below are five of the most common reasons why a groundwater pump’s life can be reduced and what you can do to limit the impact:
Inconsistent Power Supply
In some parts of the world, power supply voltage is not always steady and constant. This can be dependent on the source of power, so is often out of your control.
Power fluctuations can cause issues like over or under-voltage, phase unbalance or phase loss to groundwater pumps. While you can’t do anything about power fluctuations from the source, you can install a motor protection device for your pump.
A motor protection device (like the Grundfos MP204) can also be installed to protect the motor against voltage fluctuations. If the voltage is over or under the tolerance, the motor protection device will automatically turn the pump off.
Motor Overheating
Insufficient cooling of the motor can jeopardise your pump’s performance. For groundwater pumps, it is the water in the bore that cools the motor during operation. There are two key factors that ensure a groundwater pump’s motor is cooled sufficiently:
Ambient Temperature
The ambient temperature of the water cannot exceed the pump’s temperature tolerance. If the ambient temperature is higher, you can either increase the water flow or derate the motor. If you have concerns about the ambient temperature in your well, discuss this with your authorised pump dealer.
Water Flow
For the motor to be efficiently cooled when operating, the flow rate must be a minimum of 0.15m/sec. The faster the water flow, the more efficiently the motor is cooled.
If you can’t get the required flow, you can install a flow sleeve to the bore, which can improve the flow rate. If you have concerns about the water flow in your well, discuss this with your authorised pump dealer.
A motor protection device (like the Grundfos MP204) can also be installed to protect the motor from overheating. When the motor reaches a set temperature, the motor protection device will automatically turn the pump off.
Sand
Sand is an expected part of a groundwater pump installation. Installing a sand gravel filter in your bore will ensure there is a sufficient barrier to sand entering the pump.
If the bore has not been designed or installed correctly, the sand gravel pack filter won’t work as well . This means sand will continue to enter your well and eventually ruin your pump. It is also recommended to flush your bore before installing the pumps into it.
When selecting a groundwater pump, look for those with a higher sand handling capability, like the Grundfos SP which can handle up to 150 grams/cubic metre (SP 7 to SP 14).
Water Hammer
Water Hammer can occur when the pump starts or stops quickly and the stored energy in the water comes to an abrupt stop. If you hear a loud banging noise when your pump is in operation or the pipework shudders when your pump is in operation (starts/stops), it’s possible you have water hammer.
Over time, water hammer can damage pumps, pipework and valves and should be rectified as soon as possible. You can reduce the impact of water hammer by installing a pump with a soft start and stop functionality (like the Grundfos SQ/SQE) or alternatively you can install a pressure tank on the outlet, which will help absorb the impact of water hammer.
Pipework sizing can also be a major contributing cause, so correctly sizing pipes is critical in reducing water hammer. If you suspect your pump is causing water hammer, contact your authorised pump dealer.
Cavitation
Cavitation can occur when there is a drop in the water level and a high water temperature. Warmer water temperature can also make this problem worse. When the water level drops, the inlet pressure will drop too.
When this is combined with too high flow/velocity, it may cause the water to effectively boil, which can be devastating to the pump and should be remedied as soon as possible. Cavitation can normally be heard as a loud noise or vibration, which occurs when the vapour bubbles implode.
Alternatively, when you open up the pump, you may notice that the impeller has a lot of pitting. To prevent cavitation it is important that the pump has been properly sized (NPSHA is > NPSHR) and suits the application.
Other recommendations for preventing cavitation include removing as many bends / valves as possible (to reduce the friction loss), lower the pump inlet and increase the inlet pressure. If you have concerns that your pump may be experiencing cavitation, contact your authorised pump dealer.
You Can Trust Grundfos
Grundfos groundwater pumps are industrial quality, reliable pumps that, with the right maintenance and care, will have a long life. If you’re now ready to take the next step and purchase a groundwater pump, we can help connect you to a true pump professional. Click HERE to find your closest Authorised Grundfos Dealer.
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