Every time your sprinkler heads pop up and begin to water your lawn to ensure that it stays green and lush, a pump is responsible for supplying them with the water they need. A crucial but sometimes overlooked component of any irrigation system, pumps are available in different designs, allowing you to find the right one for your particular lawn configuration. There are a number of technical features such as capacity, power and efficiency that will play a large role in determining your selection. Consider the following questions as you design your irrigation system to ensure that your pump is primed and ready to go whenever it's called upon:
• How powerful of a motor will you need?
• How can you ensure maximum efficiency?
• What types of pumps are available?
• What performance considerations are most important?
• What features would you like to have available?
Type, Performance and Installation
In addition to providing water for lawn sprinkling applications, pumps can boost water pressure for washing cars, boats, farm equipment and more. Heavy-duty units can be used to irrigate gardens, remove water, protect against fires and for a host of other applications. They may draw on water from a lake, creek, well or municipal water supply. Pumps may be fueled by electricity, gasoline or even propane. Consider how extensive your watering needs are, where you plan to draw water from and how much power you will need when selecting the ideal pump for your irrigation system.
Surface Centrifugal Pumps: Centrifugal pumps installed above the water level are the most commonly used type. They must be filled with water, or primed, prior to operation and can draw water from reservoirs, lakes, streams and wells. Centrifugal units use a rapidly spinning impeller to push water through the pump. Priming is required because they cannot suck air on their own, they can only provide suction for water. Centrifugal pumps offer a wide range of capacities while providing a fairly constant flow rate. They offer an economical choice, though their efficiency and capacity may be somewhat limited compared to other pump types.
• May be installed either horizontally or vertically
• Horizontal installations may allow for easier inspection and maintenance
• Make sure joints and connections are airtight to ensure optimum operation
• May be powered by electricity or diesel fuel
Submersible Pumps: Unlike surface pumps, submersible pumps are installed completely underwater, motor and all. They function in a manner similar to a multistage centrifugal pump. The pump is often cylindrical, making it ideal for placement inside a well. Because they are already underwater, submersible pumps tend to operate with greater efficiency than other pumps. They may feature dry motors, which are constructed to prevent water from getting in, or wet motors, which function even when water is running through them.
• Submersible pumps do not need to be primed and are generally low maintenance
• Sleeves force water up over the surface of the pump to prevent overheating
• If using an electric model, be sure the cord is well-protected
• Submersible pumps operate more quietly than centrifugal pumps
Turbine/Jet Pumps: Turbine pumps are a sort of amalgamation of surface and submersible pumps, featuring a submerged pump and surface motor. They may be used in situations where the surface of the water supply fluctuates, because they can use suction to bring water up, providing installation versatility. With the ability to provide high-capacity performance at low-pressure levels, turbine pumps are useful for an array of functions. Turbine pumps often require a larger up-front investment and may be somewhat difficult and expensive to maintain.
• Turbine/jet pumps do not need to be primed
• Ideal for larger, heavy-duty applications, such as irrigating gardens or golf courses
• Operate quietly and take up little space
• Jet pumps must recycle water, diminishing efficiency
Propeller Pumps: Propeller pumps may be axial or mixed flow and are used in installations where the pump is located fairly close to the surface of the water supply and needs to generate a high flow rate. They do not produce high pressure, but they do provide high flow capacity. Propeller pumps are generally utilized in situations where suction lift is not necessary.
• Portable design opens up use for a range of applications
• Feature simple construction
• Available in a wide range of materials
Points to consider
|Propeller||• Simple construction
• Don't need to be primed
|• Cannot generate suction to lift water
• Provide low energy output
|Submersible||• Enclosed impellers maximize efficiency
• Don't need to be primed
• Easy to install
|• May be less economical
• Ideal for booster applications
• Can only be powered by electricity
• Susceptible to lightning strikes
|Surface Centrifugal||• Economical
• Easy to install
• Constant flow rate
• Offer a wide range of different
|• Need to be primed
• Must be located fairly close to the surface
of water supply
• Losing prime may result in pump damage
|Turbine/Jet||• Operate quietly
• Don't need to be primed
• May be used in wells
• May be used in conditions where water
|• Less economical
• May be more difficult to install, inspect and
• Require periodic impeller adjustments to
Performance and Installation Considerations: There are a number of important factors to consider when choosing an irrigation pump, including capacity. Capacity is measured in gallons per minute (gpm) and is a function of the motor's horsepower (hp), discharge pressure (measured in pounds per square inch, or psi) and the distance above water the pump is located. You'll want to find the proper balance between flow rate and pressure. Keep in mind that as the flow rate increases, pressure decreases, and vice versa. Try to avoid long runs of pipe, as they tend to reduce efficiency. Larger pumps and impellers with smooth finishes tend to operate with greater efficiency. If you live in a climate that experiences freezing temperatures in the winter, you'll need to winterize your irrigation system by disconnecting the suction and discharge lines connected to the pump, emptying water from all of the pipes and storing the pump indoors during the cold season.
• Residential pumps may be either 115 V or 230 V
• Motors usually range in power from 1/2 hp to 2 hp
• Larger motors tend to provide more volume and greater pressure
• Efficiency is lost as water travels through pipe because of friction
• Friction tends to be greater in steel pipes than plastic pipes
• Impellers may be closed, open or some combination of the two states
• Water pressure in municipal water supplies fluctuates throughout the day, so try to irrigate at off-peak
hours to utilize higher water pressure
Corrosion Resistance: Resistance to corrosion is particularly important in submersible pumps, and helps ensure that pumps continue to function properly long after they are installed.
Booster Pumps: In addition to pumping water for a variety of applications, pumps can also be used to increase water pressure to meet the demands of a large irrigation system or for washing cars and other vehicles. Nearly any type of pump can function as a booster pump, though they are often end-suction centrifugal pumps.
Flow Switch: A flow switch may be used in conjunction with a booster pump. If the switch detects water in the pipes, it will activate the pump to bring pressure up to an acceptable level. A flow switch might come in handy if your pump is hooked to your local water company's supply pipes and they don't provide quite enough pressure for your irrigation system.
Self Priming: Centrifugal pumps that are self priming don't require you to manually prime them, making operation more convenient.
Timer: Pumps that run on a timer can be turned on and off at preset times, allowing you to water your lawn during off-peak hours to save money, even if you're not around or awake. Some timers even allow you to connect to the pump from your computer, making it easy to make adjustments when you're at work or away on vacation.
Pressure Switch: A pressure switch turns a pump on when pressure in pipes is too low and off when the pressure is too high, helping to maintain peak operating efficiency. Many are adjustable, allowing you to predetermine an acceptable pressure range.
Dust-Proof Motor Control Protection and Cast-Iron Housing: If you're installing a pump out in the open, dust-proofing will help shield it against dust, dirt and other debris, which can get inside and interfere with proper operation. Cast-iron construction offers increased durability.