Table of Contents
What are Sprinkler Systems
The sprinkler systems are similar irrigation systems to rainfall that typically make use of pressurized water and liquidized fertilizers from a pipe or rubber hose that is forced through a valve and in some instances a riser pipe (a vertical connecting pipe) into a dispensing device that applies the water to an area by uniform spraying.
The dispensing device usually consists of a rotating contraption made up of small perforated closed-off pipes or various other types of device heads with small holes to spray on crops or cultivated land. However, some systems use perforated closed-off pipes that sprinkle water from the holes along their length with the absence of a sprinkler head.
The rotating device can usually either be set to rotate slow (shorter distances), fast (longer distances), or to squirt or spray without rotating at all and has a head or a gun with a nozzle, small hole, or holes from which jets or sprayed water is dispersed over the crops or land in a uniform pattern at a rate lower than the intake rate of the soil to avoid oversaturation.
In the past, water pressure was crucial in enabling the system to squirt the water to reach other plants that are beyond the end of the hose. However, now there is a range of modern systems that use different means to achieve the required pressure. These include the use of mechanical and electric pumps, hydraulics, gravity-based systems, etc.
Types of Sprinkler Systems
There are several types of sprinkler systems for agricultural irrigation and they can be categorized based on their delivery nozzles as follows:
- Rotating head
- Fixed Head
- Perforated pipe
Rotating Head Sprinkler Systems
The rotating head of the sprinkler system consists of a device that can be a pipe or a set of stout pipes that are closed off at the ends except for the small holes or nozzles. It can also be any one of various shapes of a head with nozzles that are attached to a vane or some form of rotatable pivot that spins around when pushed by pressurized water which also shoots out of the nozzles due to the pressure.
Rotating sprinkler heads have the top end nozzle-bearing component fixed to a swiveling bit like a frame on a center pivot that is designed to swivel or spin when pushed by pressurized water or driven by a system like hydraulics. It may alternatively use a ball as the pivot.
It can be attached to the ends of the water pipes or hoses but can also be fastened to riser pipes at given intervals along the length of the lateral pipes or hoses. The sprinkler heads are sometimes mounted on riser pipes whose height is above or below that of the crops and may be able to rotate 90° or 360°. Other types have pipes that run over the crops.
The intensity of pressure required Pascal (Pa) (standard SI unit for pressure measurement) for sufficiently effective sprinkling that will have the necessary reach ranges between 2.0 to 4.0 kg-cm −2 with the application rate being between 4.0 to 20.0 mm /hr −1 depending on factors like furrow spacing and nozzle size.
Rotating heads can be applied to a wide range of application rates and plant spacing due to the varying rates and range of applications possible with the rotating head. The effective range for dispersal is the pressure that will yield between 10 meters to about 70 meters per head. A range between 16 meters and 40 meters per head is considered to be the most practical for normal operations.
Fixed Heads Sprinkler Systems
Fixed sprinkler heads have a top-end nozzle-bearing component but do not have the swiveling, rotating, or spinning facility so cannot dispense water outside of their fixed radius or line of dispersal.
The rotating heads require additional pressure to spin their heads therefore the fixed heads require less pressure to function and can be used even with low water pressure. For this reason, they are sometimes used to irrigate small lawns and gardens. Perforated lateral lines are sometimes used as fixed sprinklers.
Fixed head sprinklers generally apply more water per unit area than rotating sprinklers and are therefore more suitable for use on soils that have higher intake rates as oversaturation may rapidly occur in soils that have lower intake rates.
Pop up Sprinkler System
The pop-up sprinkler or spray system is a type of fixed head irrigator with a retractable dispensing head that briskly emerges and retracts from a small housing chamber in the ground just below the surface where it is connected to the subsurface pipe network.
The pop-up or spray sprinkler system does not typically rotate and therefore usually has a fixed radius of water dispensary that covers a relatively restricted area and as such is used mainly for smaller sizes of lawns.
Emergence and retraction of the pop-up sprinkler head are usually achieved by a system that uses water pressure from the movement of water through the supply pipes that pushes the head upwards opening the valve and exposing the nozzles with the aid of a sliding or rolling function built into the shaft and housing.
Once the pressure drops when the supply is shut off, the pop-up sprinkler head slides back down into its housing level with the ground’s surface as only the water pressure keeps it extended upwards.
Perforated Pipe Sprinkler System
The perforated pipe system is a simpler system that uses a series of pipes that typically includes a main supply pipe, sub pipes, and the lateral pipes that run between the furrows.
Nozzles or simple holes are made at equidistant intervals along the length of the lateral pipes or hoses through which the pressurized water is sprayed uniformly over the cultivated land or developing crops. This system utilizes relatively low pressure roughly 1kg-cm −2 with an application rate ranging between 1.25 to 5cm per hour depending on factors like spacing and water pressure.
Types of Sprinkler Systems Designs
Sprinkler systems can also be classified based on their designs and portability; they have the same fundamental method of irrigation of crops or land by spraying pressurized water and sometimes liquidized fertilizer through a system of pipes or hoses. The only difference is the specific type of design of the system used to deliver the water. They are as follows:
- Permanent system
- Semi-permanent system
- Portable system
- Semi-portable system
- Solid set system
- Set-move system
Permanent Sprinkler Irrigation System
Permanent systems as the name suggests is one whose major components are installed to be reused repeatedly in the same fixed position on the land without moving or removing.
The pumping station or plant is secured in a fixed position to be fed from a fixed body of water that is presumably renewable so that it can continue to provide water to run the system.
The main, sub-mains, and lateral lines are all buried in predetermined fixed positions on the agricultural land where they cater for repeated agricultural cycles. The sprinkler heads and nozzles are permanently attached to the risers located at given intervals either on surface systems or overhead structures.
Lawn Sprinkler Systems
Lawn sprinkler irrigation systems are a type of permanent sprinkler system that is specifically designed for the irrigation of different kinds of lawns. It typically utilizes subsurface piping networks that are concealed to preserve the aesthetic value of the lawn landscape.
The entire expanse is divided into zones where the subsurface pipes that are run throughout the area have one or more outlets where the lawn sprinklers are attached. Each sprinkler caters to a specific radius that it moisturizes within the zone or encompassing the whole zone. Other types of irrigation devices and methods besides sprinklers like bubblers and drip systems can also be used with the subsurface piping for lawn irrigation.
Lawn irrigation systems are used in a wide range of lawn types from expansive golf courses to small domestic turf lawns. Two basic lawn sprinklers are usually deployed for lawn irrigation namely pop-up sprinkler/spray heads and rotor sprinkler heads.
The semi-permanent system is similar to the permanent system due to its also having a fixed pumping station, subsurface mainlines, and sub-main lines although some may have these lines on the surface or even in overhead structures.
The lateral lines in the semi-permanent sprinkler irrigation systems are portable and not permanently fixed and can be removed for use in other areas where they are attached to risers that are arranged at intervals along the sub-main lines.
Portable Design System
The portable system of sprinkler irrigation is designed for the entire system to be movable so that it can be effectively used at different locations. There is a complete absence of permanently laid piping in portable systems.
The pumping system, sprinklers, riser pipes, other piping, main lines, sub-lines, and lateral lines are all set up so that they can all be disassembled and moved to any other location with an accessible source of water where the components can be reassembled.
The center pivot sprinkler irrigation system is a portable system that uses several segments of usually galvanized steel or aluminum piping that are assembled according to the supply system and supported by a self-supporting structure of beams or trusses.
The entire structure housing the pipes is usually mounted on a supporting wheeled platform or frame so that it is mobile. The sprinklers are positioned strategically along its frame and the system dispenses water in a circular motion and receives water through the main supply that runs through the center of the structure.
Crops that are to be irrigated with this system are sometimes planted in a circular configuration to correspond with the center pivot’s pattern of water delivery. This type of application system is referred to as a LEPA (low energy precision application) method. Though this method was originally strictly water-driven, it is now used with hydraulic and electric motor systems.
The hose end sprinkler system is a simple and portable watering method that uses a single hose or pipe with a sprinkler attached to the end. The sprinkler is usually a smaller version of larger types that cater to larger areas and sometimes have a spike that can be thrust in the ground, or wheels/sled skis to enable pulling them across the ground to other locations.
The semi-portable irrigation system uses very similar equipment to the portable one. Most of it is the main, sub-main, lateral lines, riser pipes, piping components, hoses, and sprinklers all detachable for disassembly. The only difference is the fixed pumping plant and water source which are permanent.
Solid Set System
The solid set sprinkler system is slightly similar to the semi-permanent system in terms of the whole system being permanently fixed except for the lateral lines which are detachable.
The main difference is that in the semi-permanent setup, the lateral lines are moved frequently and as needed whereas, in the solid set system, the lateral lines are left in their position for the whole season from the very beginning till the end.
The set-move sprinkler irrigation system is a portable design that dispenses water while in a fixed position. Water is fed to the system through the main supply line pumping from the source.
When sufficient water has been applied, the water is shut off, the lateral sprinkler lines are drained and moved to other either riser pipe positions or directly onto outlets with valves and housing where they can be screwed on while the entire system is manually or mechanically moved to the next area for irrigation.
Set-move systems typically have one mainline with one or two lateral lines on either side though there are several different configurations and designs that may have structural and operational differences. There are four basic ways of moving the set-move sprinkler irrigation systems currently in use which are as follows:
The hand-move method of relocating or moving a set-move sprinkler system involves the manual uncoupling of the lateral pipes and hoses and carrying them to the next location where they are reassembled and reconnected all by hand.
Older hand-move sprinkler lateral lines were made from aluminum of different diameter for quite some time but modern versions have since been developed and are now made from HDPE (High-Density Polyethylene ) a far more durable and flexible material which are available in 50mm to 150mm (2inches to 6inches) in diameter and six, nine, or twelve meters long.
The tow-move method of moving set-move sprinkler systems uses a towing line attached to the mainline end of the lateral lines to the next area to be irrigated. The towing is typically done with a tractor and the problem of friction and greater crop damage is surmounted by adapting the lateral lines and attaching skis or wheels to aid movement. This method requires great care to be taken while dragging the lines to avoid damaging the crops. The tow-move method is suitable for forage and row crops.
The side-roll or wheel-move sprinkler system is a mechanically operated apparatus that consists of a sectionalized lateral pipe that acts as an axle for wheels that are fastened to the middle of each section suspending the lateral pipe above the ground.
Sprinklers are attached to short risers on one end of each section of piping. These sprinklers sometimes have self-leveling designs to tilt the risers when the water pressure drops and drainage valves located opposite each riser automatically open for the quick drainage of the lateral pipe for the quick redeployment of the system.
The side-roll system is powered by a gasoline engine and transmission at the center or sometimes at the end of the lateral pipe with a reverse gear that enables the easy locomotion of the system across the agricultural field.
Sizes and dimensions of side-roll sprinklers may vary but industrial-scale systems may have lateral lines that are up to 800 meters (roughly half a mile) long and between 100mm and 125mm (4 – 5 inches) in diameter. Each lateral section on this size of the system is usually about 12.2 meters or forty feet long. Spacing along the mainline can be up to sixty feet apart.
The gun-type apparatus for the set-move sprinkler irrigation system consists of a high volume and capacity sprinkler which is usually a larger single unit that can shoot jets or streams of water further than average. It is typically mounted on a wheeled cart or trailer and can be moved by tractor or manually.
The gun sprinkler or sprinklers that are used in this system can have capacities that are up to 4700 L min−2 roughly 1250 GPM (gallons per minute) and the diameter of the effective reach of the dispersed water being up to 180 meters roughly 600 feet. The recommended operating pressure is between 70 to 130 psi (pound per square inch).
Parts of a Sprinkler System
The sprinkler irrigation system is made up of several parts that all play important roles that must all be functional for their successful and efficient operation. The components are outlined below:
- Pumping unit/Pumps for sprinklers
- Fertilizer application units
- Piping network
- Sprinkler heads
- Couplers and fixing accessories
Pumping Unit or Pumps For Sprinklers
The pumping unit of a sprinkler irrigation system is basically a water pump which is a mechanical device with typically an electric motor or internal combustion engine that runs on fuel or other energy sources to generate suction power to move water from its source to selected irrigation zones.
Selecting Sprinkler Pumps
Sprinkler irrigation systems are designed for efficient delivery while conserving resources. Selecting and installing a suitable sprinkler pumping system is determined by a few important factors.
- The Size
- The Height
- The Distance
- The Power Needed
- Type of Plants
- Type of Soil
- Type of Climate
The dimensions of the area that is intended for irrigation. The land size, crop type, and soil type will determine the number of sprinkler heads and necessary pumping and suction sprinkler pump engine capacity needed in terms of GPM (gallons per minute) and PSI (pounds per square inch). Sprinklers are generally rated based on GPM and PSI.
The altitude of the area intended for irrigation and the total distance the water must be lifted. The suction head (the height the water travels between its source and the pump) is a very important factor when selecting a sprinkler pump and should not exceed twenty-five feet (25ft) from sea level. The discharge head (the height the water travels between the pump and the irrigation zone) is as crucial as the suction head and together they constitute the total head.
The total distance the water must travel to reach the irrigation zones is an important factor when selecting an irrigation pump including those for sprinklers. This is mainly due to decreased pressure with increased distance. The total distance must be established along with the total head to determine the capacity of the pump and pipes required.
When the distance between the pump and the furthest sprinkler is less than one hundred feet (100ft), the standard 1-1/2 inch discharge pipe will suffice. However, if the distance to the furthest sprinkler on the system is between one hundred and three hundred feet (100-300ft), then a 2″ inch discharge pipe will be needed.
Similarly, a three to six hundred feet (300-600ft) distance will require an increment in the diameter of the discharge pipe to 2-1/2 inches. There is a discharge pipe diameter single size increase for every three hundred feet of horizontal piping for sprinkler pump irrigation systems. This generally applies to the suction side as well when used over significant distances.
The Power needed
The sum of the overall power requirements must be analyzed and incorporated into the overall establishment plan. The engine capacity of the pump, its energy output requirements, and that of any backup systems have to be established.
Most average pumps are dual-voltage rated operating between one hundred and fifteen and two hundred and thirty volts. (115volts and 230volts) Larger pumps that are 2-1/2HP (horsepower), 3HP, and more operate at 230volts or 208/230/460 3 phase. Gas-powered pumps are also available.
The Type of Crop
The type of crop or turf to be irrigated, their average height, and their moisture requirement will determine the volume of water and frequency of application necessary which will, in turn, determine the type of pumping system required.
The Soil Type
The specific soil type and general topography present at the irrigation zones is another factor that influences the type of crops and degree of irrigation that is suitable and therefore what types of pumps are needed.
The specific climate statistics for the region in which the agricultural or other-purpose area of sprinkler-based irrigation is to be established is important so that it will work in synchrony with the environment. This will help eliminate waste of resources and damage to crops from either oversaturation, undersaturation, or creating an environment that promotes the spread of disease.
Fertilizer Application Unit
The fertilizer application unit is basically a sealed fertilizer tank with various connecting appendages, tubes, and pipes that enable it to be connected to the already existing sprinkler system where the water is substituted for the fertilizer which is poured into the tank and attached to the sprinkler system.
The piping network refers to all the various pipes and hoses that are components of the sprinkler system. They may start right from the pipes or hoses that are submerged in water to suck it up to the pump for instances where surface pumps are used and include the main lines which convey water directly from the source through the pump to the sub-mains or secondary pipes.
From here, it moves to the lateral pipes or hoses that in turn feed the sprinklers through the riser pipes or other pipe appendages like joints or valve housings. All these parts are generally now made from different materials.
Portable systems are mainly manufactured using aluminum, PVC (polyvinyl chloride; a commonly produced synthetic plastic polymer), or HDPE (high-density polyethylene; a durable petroleum-derived thermoplastic polymer).
Galvanized steel or aluminum pipes are generally used for center-pivot systems or in some instances just for the laterals. Buried laterals and main lines are typically made of wrapped steel, cement, asbestos, and PVC.
A water meter is used to measure the approximate water volume used in the system to know the system requirement and to know when too much or an insufficient volume is used. It also aids in the early detection of unnoticed leakages.
An electricity meter is used to monitor and regulate the use of electricity either from a commercial power supply or farmyard generation plant. It is important to supply the correct voltage to the pumping system to avoid damage from a wrong voltage or surges of voltage from the periodic unregulated power supply.
A functioning pressure gauge is an important accessory in any pressurized irrigation system because it shows the pressure necessary for the efficient and uniform operation of the system and shows when the pressure is either insufficient or too much. The pressure gauge can also enable the early detection of leaks that cause a pressure drop.
A water gauge is important for water storage facilities like reservoirs and water tanks. It is used to know the volume of water contained in the receptacle. This helps to monitor the volume of water to know when the receptacle is filled to its maximum capacity to avoid overflow, or when the water level has dropped to a depth that may require additional water before the next irrigation.
A sprinkler timer is an electronic device very similar to an irrigation controller that is used to automatically and remotely engage and disengage (switching on and off) sprinkler irrigation systems.
The timing or controlling device can be set to start and stop the watering action of sprinklers and other irrigation systems as needed. Some advanced types are equipped with sensors that are installed in the soil and can detect low water content and switch on the sprinklers automatically to moisturize the soil and shut them off when sufficient saturation has been reached.
The controller/timer consists of a central control unit that is usually digitalized and can be pre-set for numerous calibrations. This unit is connected by wiring, wifi, or infrared technology to sensors, digitally controlled switches, and a system of gears that operate and monitor the system.
A projecting flat collar-like rim is sometimes built with screws or rivets around its circumference on a pipe or other irrigation system accessory for strengthening or additional attachment and for maintaining the stability of the pipe. It also acts as a point of access to the pipe as it can be uncoupled for cleaning or some other form of maintenance.
The heads of the sprinkler systems as described above under the types of sprinkler systems are the main dispensing unit of the apparatus; the sprinkler heads are often located at the top of the device and bearing holes or nozzles through which the water is forced out at high pressure in jets, pulses, pouring, splashing, or more commonly, sprinkling or spraying. There are two basic types of sprinkler heads which are fixed and rotating heads.
Couplers and Fixing Accessories
Components of the sprinkler irrigation system assembly that aid in connecting individual sections of the piping network with other sections of pipes and other parts of the system like valves, joints, input and output of the pumping plant, storage tanks, or reservoirs, fertilizers application units, etc.
They aid in the coupling and uncoupling of the system and ease of component replacement. Some of the main and important couplers and other accessories are outlined below:
Coupling devices or components are system appendages that typically have provision for the efficient attachment of two or more shafts, pipes, or other components of a system at their endpoints for the uniform and unhindered transmission of fluid.
The air-tight attachment is usually achieved with the aid of screw-threading on the coupling unit which is termed to be male or female, that corresponds to threading on the shaft or pipe that screws into place on one end and permits the flow of water from the attached pipe or hose through the coupler and the next pipe coupled to the coupling unit on the other end.
The main coupling components that are commonly used in sprinkler irrigation systems that aid in effective water dispersal, assembly, and disassembly of the system are:
Union in plumbing: Nipples
Union nipples in plumbing are small coupling accessories typically consisting of a short pipe with a thick hexagonal ring in the middle for tightening or loosening with a wrench or spanner and male pipe threads on either end to facilitate coupling or screwing into place with pipes at both ends that are usually fitted with female threading.
A bend in plumbing is a generic term for any of the coupling joints of a water system that diverts or changes the direction of the flow of water or fluid that the system is carrying. Elbows joints are also a type of bend that diverts the water to one side of its original tangent of flow and is shaped like an elbow. A tee joint is also a type of bend joint that diverts the water flow from a central supply to two lateral outlets at right angles to different directions and is shaped like the letter T and fitted with female threading to enable coupling with male-threaded piping.
Reducers in Piping
Reducers in piping and sprinkler systems are short pipe joints that have the standard circumference of the pipe size bore being used on one end and a smaller bore on the other end. This is to reduce or increase the hydraulic flow rate of a system depending on the particular requirement or to adapt a system to a piping network with different pipe sizes.
A hydrant in an irrigation system is a major water dispensing device that is connected to the main water supply strategically located at a fixed point away from the water source but closer to the agricultural fields. It has a provision for the attachment of a main pipe or hose and supplies pressurized water that can feed into the sprinkler irrigation system.
Butterfly valves are a series of plumbing devices that are designed to regulate the flow of liquid in an irrigation system. They utilize the quarter-turn rotation of a wheel regulator that controls a disc and seal centrally located within the valve housing that is the same size as the pipe bore. The disc moves parallel to the flow of water when opened allowing a steady flow but increasingly obstructs the flow the more it is rotated against the flow and completely shuts off the flow once it rotates fully aligning with the circumference of the pipe.
Plugs in plumbing are small appendages of hydraulic or pneumatic tubing or piping that are used to close off the open ends of pipes or hoses. They typically have male threading that screws into place and seals off the open end or appendage boring on pipes.
Repairing Sprinkler Systems
How to Repair a Sprinkler Head
Adjustments of sprinkler heads are often necessary to either increase or reduce the reach (distance covered) of the water’s trajectory or the direction of the spray and radius covered to suit the specific dimensions of the area intended for irrigation.
The adjustment of most sprinklers and sprinkler heads is easy and only requires the loosening or tightening of a small screw located on the sprinkler head. Turning the screw clockwise with a small screwdriver will usually reduce the pressure with which the water will be thrust from the nozzle or nozzles. Screwing anticlockwise will increase the pressure and the reach of the spray.
A screw can also be loosened or tightened to change the direction of the spray. Simple and clear instructions are stated in bold writing on the sprinkler heads.
How To Adjust Rainbird Sprinkler Heads
Rainbird sprinklers are a relatively reliable type of irrigation sprinkler that is commonly used. However, there seem to be many who have difficulty adjusting these particular sprinklers to suit their specific requirements. The following is an outline of the adjustment procedure:
Changing The Nozzle Head
- Remove the previous nozzle head by turning it anticlockwise by hand.
- Take out the filter screen below the nozzle.
- Insert a new replacement filter screen in the same position as the previous one.
- Gently screw on the new nozzle by turning the head clockwise until it can’t turn any further.
Adjusting The Watering Direction
The water spraying direction can be adjusted manually by rotating the stem by hand to aim the slots where the pressurized water is squirted towards the desired direction for irrigation.
Adjusting The Spray Distance
Changing the squirting distance is done by adjusting a screw located at the center of the sprinkler head with a flat screwdriver. Turning the screw clockwise will reduce the pressure and distance sprayed. While turning the screw anticlockwise will increase the pressure and distance of the spray.
Adjusting The Spray Pattern
Adjusting the spray pattern can only be done on certain models with this option like the 12/15/18, and 2SA, 42SA, 42SA+, or 52SA series. The adjustable spray radius ranges from 0° to 360°.
To adjust the spray pattern, twist the threaded collar to the right or left while the system is turned on to see and produce the desired spraying patterns.
Water sprayed reaches a shorter distance than required.
The spray head does not pop up completely. (Partially emerged)
The spray is not in the desired pattern even after adjustment.
Water is only dribbling out of the popped-up head and won’t spray.
Water slowly seeps from the sprinkler even after the valve that regulates the flow is shut off.