Sprinkler Heads and Nozzles
The sprinkler head is the outlet of an irrigation system. The nozzle is the topmost part of the sprinkler head. The nozzle is the device that creates the spray pattern and establishes its direction. Nozzles come in many different configurations, each of which has a specific application.
A fixed spray head emits a fan of water in a fixed pattern over a section of a circle. Many of the fixed spray heads use interchangeable nozzles that determine the pattern – quarter circle, half circle, full circle – and the radius of the water throw.
Bubbler irrigation is a low-pressure, localized system that produces a flow of water that floods into a basin around a tree to soak the soil and reach the tree roots.
Drip irrigation is, as the name implies, the slow application of water to the root system of multiple plants such as is found in flowerbeds. The water is delivered either onto the soil surface above the roots or directly to the root zone, referred to respectively as surface drip irrigation and subsurface drip irrigation. Drip irrigation can also be used in grassy areas that are too small to spray, such as the strip between the municipal sidewalk and the road. The drip irrigation method helps reduce water evaporation and runoff.
Misting nozzles deliver water in a mist so fine that it’s almost like smoke. In these systems, the water barely touches the ground. Misting systems are used most often in greenhouses and also a popular choice for deck and patio cooling.
The difference between rotor heads and rotary nozzles
Rotor heads are high volume sprinklers that cover very large areas using a single stream of water over a radius of up to 100 feet. The shortest distance you can set a rotor head for is roughly 20 feet, so they’re used to irrigate places such as golf courses, parks, and some commercial properties. They can be set in an adjustable arc from 40o through to 360o. Some of the large turf rotors, called impact rotors, have a swinging arm that is repeatedly pushed into the water stream. These are the sprinklers that generate that familiar sputtering “shhh-tik-tik-tik” sound. The striking action scatters the stream and helps to establish a uniform watering area around the sprinkler.
Rotary nozzles, on the other hand, are used for smaller areas, as little as 5 feet. They deliver multiple streams of water in a circular pattern. Rotary nozzles generally deliver the water at a lower rate to increase absorption rates.
Many rotary nozzles incorporate an interesting feature called MPR which stands for “matched precipitation rate”. In an irrigation system, the precipitation over each area or zone should be the same, regardless of the degree of arc of the spray. MPR nozzles allow sprinklers with various arcs to be mixed in the same zone while maintaining even water distribution rates.
The idea of MPR becomes a little easier to follow if you envision three different sprinkler heads covering different degrees of a circle:
Each of the quartered sections of the circle would have water distributed at the same rate of inches per hour so the precipitation is matched. MPR nozzles were first introduced in 2003 and have become very popular over the last 15 years as they achieve uniform coverage while preventing water from being wasted.
Pop-up sprinkler heads are those that retract into the ground when not in use. This protects the heads from lawn mowers and also eliminates the tripping hazard that fixed-in-place heads can present. Pop-up heads are most often used in residential and small commercial applications in zones with plant materials of similar watering needs. They can be fitted with various nozzles to match the contour of the landscape. Pop-up spray heads are generally designed for small areas with a spray radius of between 3 and 15 feet, although some manufacturers have developed nozzles to convert a pop-up spray head to a rotor for covering greater distances. Many of the pop-up heads have covers that protect them from dirt and other debris that can clog them. The standard height for a pop-up head is four inches but they are available in heights up to 12 inches. Many of the pop-up heads have a self-cleaning feature that purges dirt and debris from the nozzle after each use.
Shrub style heads are fixed above ground on top of a section of pipe but because of the tripping hazard they present, it’s probably best to avoid this type unless a very tall riser is needed to raise the spray over the tops of tall shrubs. They are not recommended for areas with sidewalks or patios, or where children play.
Sprinkler heads can be made of a variety of metals including brass and zinc. There are those who still think that metal equals durability, and in previous years they might have been right. Today’s plastics, however, are engineered to perform just as well as, if not better than, metal sprinklers and have the added advantage of being resistant to minerals contained in hard water. Metal attracts such minerals, as anyone who lives in a hard water area can confirm. Those minerals are not attracted to plastic and they do not stick to it. And to cap it off, replacing plastic heads and nozzles costs less than metal ones.
One important thing to remember about head and nozzle selection is that mixing head types on a single circuit will defeat the efficiency of your sprinkler system. Each type has a different precipitation rate so that one type of head may put out an inch per hour while a different type may put out twice that amount. The result of mixing types is that one of those areas on the circuit is going to be either over- or under-watered. Professional irrigators have irrigation system design capability and fully understand the different types of heads and nozzles. They will help you ensure that your lawn and garden receives the right amount of water every place it’s needed.
For sprinkler system maintenance and repair you can count on, call Smart Earth Sprinklers today at (512) 694-1147.