Top 10 Pump Questions

Pumps are a lot less complicated than they appear at first glance. Understanding a few basics will go a long way! 
1. What style pump do I need?
For most of the applications that landscape contractors come across, there are two main styles of pumps – centrifugal and submersible. Centrifugal pumps are most often used for turf irrigation and pressure boosting applications, where the pump is used intermittently. Submersibles are usually recommended for water features, dewatering, and applications when the pump can be in constant use. Well pumps, used in domestic water and irrigation applications can be centrifugal (shallow well) or submersible (deep well).
2. What’s the difference between a submersible and a centrifugal? 
These pumps operate just as the names describe. Submersibles are at least partially, and sometimes fully, submerged in the water. The water keeps the pump motor cool, allowing it to operate for long periods of time, sometimes constantly. Centrifugals use the centrifugal force of an impeller to sling the water through the pump, efficiently increasing pressure.
3. Does size really matter?
You bet! Be sure to properly size the pump to the application or you could end up with too much or too little pressure or flow. Imagine sprinklers spraying 15 ft. in the air or a water feature that only drips… both can be the result of an improperly sized pump. Use a pump data calculator or worksheet to determine the proper size pump, for the application.
4. Why is it called self priming?
Centrifugal pumps are made to pump water, not air. Before using a centrifugal pump, we need to “prime” the pump by filling the pump case with water. "Self-priming" refers to a centrifugal pump that is able to create a vacuum to pull water into the pump housing even if the case is not completely full of water (there must be some water in the pump case). A straight centrifugal pump, that is not self-priming, must be fully primed (completely full of water) or it will not function. 
5. My pump doesn’t suck?
It is a common misconception that pumps suck water and spit it back out. Not true.  Instead, a partial vacuum is created as air is expelled from the pump case.  The atmospheric pressure then forces water into the pump to replace the void. The pump increases the velocity of the water, which increases the pressure at which it flows. So, pumps don’t suck… they create a partial vacuum.
6. Why do most pump issues happen on the suction side?
There are many opportunities for disruption to flow before the water reaches the pump. Often there is a small air leak, allowing air to enter the system. Blockages can occur and breakage of pipe or hose is not uncommon. More often than not, investigating the path to the pump will reveal root causes of pump performance issues.  Learn more about troubleshooting centrifugal pumps.
7. Why does pipe size matter?
The size of the pipe plays a huge role in the amount of pressure required to move the water and achieve the appropriate flow rate. It takes more energy to push a lot of water through a small pipe, because the pipe causes friction losses in velocity. However, to operate efficiently, most pumps require some back-pressure, so if the pipe is too big, the pump will be inefficient and probably noisy. The optimal speed at which the water travels through the pipe is 5 velocity feet per second + or – 1.
8. Where should you measure the water level? 
When sizing a pump, one of the important data points to consider is suction lift – the vertical distance between the water level and the pump inlet. In some applications, water level can change dramatically and it is important to take this measurement from the lowest possible water level.
9. Is electrical pump protection necessary?
Pump protection is always a good idea. Pumps are an investment and the shut-off protection provided by a pump control like a Munro SmartBox safeguards that investment in the event of run dry or overheating.
10. Should I cover my pump to protect it from the elements?
Just as electrical pump protection is a good idea, so is physical pump protection. However, sometimes well-meaning homeowners or installers cover pumps with plastic bags, buckets, or other things that do not allow enough ventilation – that can cause the pump to overheat. Pump enclosures specifically designed for pumps, like the Munro Universal PRO Enclosure are the best protection from the elements.