Select an Irrigation Pump

The Pump Curve

There are various types of pumps that are used to perform certain tasks. Many variables need to be considered when selecting the right size and type of pump. Choosing the wrong pump size for your irrigation system can result in a lot of wasted power.

If you choose to select your pump without using a pump dealer, one of the main things you will need to obtain is a pump curve. A pump curve, which is created by the pump manufacturer, shows the pump performance in an illustrated graph. Lower flows results from higher pressures and higher flows results from lower pressures.

The pumps performance is affected by two variables. The horsepower of the motor attached to the pump is the first variable. A pump has two parts the pump which actually moves the water and the motor which moves the pump. Bigger motors results in more volume and pressure giving an advantage if you have a pump that can be attached to different sizes of motors.

Size of the impeller is the second variable. The impeller is responsible for moving the water by spinning and causing a centrifugal action. Higher pressure is created when a larger impeller fits tighter in a case which prevents slippage. If you have higher pressure than what your system requires it may cause your system to waste energy. Determining the proper pump really boils down to selecting a model and size that produces the GPM (the flow amount that the pump is able to produce) and head (measured in feet of head, the amount of pressure the pump is able to produce). Pumps are generally sold with custom impeller sizes. A way to determine the impeller size you need is to draw a impeller curve through the feet head/GPM intersecting point making your curve parallel to the other impeller curves. Ultimately it would probably be easier and time saving to contact a pump dealer and provide them with your GPM and feet head you are looking to pump and they can provide you with the best fit for your irrigation needs.

When choosing an irrigation pump, the ultimate goal is to transfer water to your lawn in themost efficient way possible. An efficient irrigation system is one where the pump matches the needs of the water source, the piping system, and the irrigation equipment. Equipment would include the total length of the sprinkler system's longest pipe run, the pipe diameter, and the collective capacity of the sprinkler heads in gallons per minute. Since many different pump designs are available, you should be able to find one that is just right for your needs.

When making your decision, look at the technical features of each pump type - capacity, power, and efficiency. You need to already know the extent of your watering needs, the source of your water supply, how much power you will need, and the features you would like to have available. Doing so will insure that you will choose the ideal pump.

Pump Type	Benefits	Points to Consider
Propeller	Simple construction Doesn't need to be primed Efficient at pumping very large flow rates at low TDH Can pump some sand Can use electrical or tractor power, as well as internal combustion engine Portable	Cannot generate suction to lift water Provides low (less than 75 feet) energy output Cannot be valved back to reduce flow rate Critical intake submergence depth
Submersible	Compatible with deep wells and crooked wells Enclosed impellers maximize efficiency Doesn't need to be primed Easy to install Can be less expensive than vertical turbines when needing smaller diameters Ideal for booster applications	May be more expensive when using large diameter pumps Can only be powered by electricity More susceptible to lightning strikes Requires water movement past motor
Centrifugal	Simple Highly efficient in many applications Economical and adaptable to a wide range of conditions Easy to install Can use electrical or tractor power, as well as internal combustion engine Constant flow rate Doesn't overload with increased TDH Vertical centrifugal may be submerged with no need for priming	Priming required Must be located within 20 feet of the surface of water supply Losing prime may result in pump damage Motor may overload if the TDH is much lower than the design value
Turbine	Quiet operation Can use electrical power or internal combustion engine High TDH and flow rates provided with high efficiency Doesn't need to be primed Compatible with well use May be used in conditions where water depth fluctuates	May be more difficult to install, inspect, and repair Impellers must be periodically adjusted to maintain high efficiency Cost of initial installation higher than centrifugal pump Repair and maintenance more expensive than centrifugal pump

Select an Irrigation Pump

Propeller

Submersible

Centrifugal

Turbine