What is a sprinkler nozzle?
The spray nozzle is a fixed-spray sprinkler, which allows for a fine spray to be applied to a part-circle, a full circle or a square or rectangular surface.
The spray-head consists of two parts: the body and the nozzle.
The body of a spray head is buried, allowing for a telescopic section to emerge (pop up) from the soil with the pressure of the water and a spring allowing it to retract when irrigation stops.
An irrigation nozzle is attached to the body, determining the flow rate and surface area to be irrigated.
The pop-up height indicates the height of the spray above ground level (5 cm, 10 cm…).
The spray radius ranges from 2 or less metres to 5 metres according to the nozzle type.
There are spray head bodies of different heights allowing for the nozzle to rise to a level which is higher or lower, according to its application. For lawns, a height of 5 to 12 cm is used, while the irrigation of flower beds requires a height of 15 to 30 cm to allow the stream of water to pass above the plants. As far as the nozzles are concerned, their very wide range on offer allows the user to make all sorts of configurations in the field. They should be of a perfect quality in order to obtain a good distribution of the irrigation water, as well as an appropriate radius.
Main features of the spray heads:
The pressure: a pressure of 1 to 3.4 bar is required. The nozzles are very sensitive to very high pressure. The use of systems that are regulated by valves or by a pressure regulator has proved to be absolutely vital, because, given the fineness of the droplets, they require a certain inertia to achieve their recommended ranges.
Precipitation rate: a new generation of rotary spray nozzles has appeared on the market. Their average hourly precipitation rate of 25 mm/h is less than 30 to 50% of the precipitation rate of the traditional nozzles, thus preventing the soils from becoming saturated and avoiding losses through run-off.
The flow rate: With their lower flow rate of around 60% of the conventional spray heads, the rotary nozzles allow for a greater number of sprinklers per zone to be installed, thus reducing the complexity and overall cost of the system.
The distance of throw (radius): Optimal distribution of the water through multiple and rotary jets for a distance of throw ranging from 0.6 to 7.4 m.
Spacing: of 2 to 5 metres. The overlap distances are the same as for the rotors and impact sprinklers.
Performance. The pop-up heights are generally of 5, 10, 15 and 30 cm from ground level. The option is chosen according to the heights of the plants, turf-grass or flower beds.
The options: Flow rate reducers or pressure regulators. The valves prevent the sprinklers from draining at the bottom. Then there is an option of adapters for bubblers or microjets, and height extensions.
Spray head nozzles: selection criteria
What are the main criteria to be used when choosing spray heads for a subsurface sprinkler system?
Sturdiness and durability are essential since the sprinkler has to stay in place for a long period of time. A kind of “threaded tie rod” (what is this?); capable of resisting extreme conditions, is used to increase the overall strength.
The throw or radius is always less than 5 metres (otherwise rotors should be used for irrigation). They should be easily adjustable by using a screw or piston plunger.
The spray head body should be compatible with all the threaded nozzles.
The nozzles should be adjustable for irrigating at 5° to 360° or a fixed angle.
An extra orifice is sometimes inserted in order to allow for the foot of the sprinkler to be irrigated and thus avoid dry areas forming around the sprinkler.
Finally, a “dust cap” prevents the sprinkler from becoming blocked at start-up.
Price of a spray head
An individual sprinkler is not expensive (between 10 and 20 €), and it is also preferable to use sprinklers of a known brand, as proof of reliability.