There are many types of spray nozzles and the shape of their spray pattern is the most basic distinguishing characteristic. Nozzle selection typically begins by determining the type of spray pattern required for a particular operation.
Nozzles are classified by the shape of their spray pattern, but also by application or by their specific benefit, such as drift control.
Flat Fan Pattern Nozzles
The orifice of flat fan nozzles is elliptical in shape and forms a triangular fan-like spray. The spray volume is highest at the center of the pattern and drops off towards the edges. Thus, the spray pattern should be overlapped a minimum of 30% to ensure even coverage. Also, setting the nozzles at a 10-15° angle to the boom will allow the fan patterns to bypass each other.
Drift can be reduced by using a wider spray angle thereby allowing the boom to be set lower to the target. The lower boom setting also helps uniform spray distribution over the entire length of the boom.
Regular flat fan or tapered spay tips are ideal for broadcast spraying of herbicides and insecticides.
Flat Fan nozzles include :
- Wide pressure range flat fan spray nozzles :provide a very good spray distribution over a wide range of pressures
- At low pressure (below 30 psi / 2 bar) and higher flow rates : for low volume applications, often used for soil applications and spraydrift reduction – bigger droplets more resistant to drift.
- At higher pressure (above 40 psi / 2.5 bar) : used in foliar applications to improve target coverage – finer droplets more prone to drift.
- Even flat fan spray nozzles : non-tapered spray patterns provide even spray with the volume at the center the same as at the edge. Thus, the spray pattern does not need to be overlapped. Even flat fan spray tips are used for band spraying.
- Deflector or Flood or Anvil flat spray nozzles produce a wide angled flat fan pattern. Change of pressure affects the width of the spray pattern, more than with widepressure range flat fan nozzles.
- At low pressures flooding nozzles produce large droplets in an even spray. Compared to wide range pressure flat fan nozzles, drift can be reduced up to 50%. Best results are achieved at low pressure with a double -100%- overlap.
- At high pressures they produce smaller droplets, even smaller than other flat fan nozzles at the same flow rate.
- Flood nozzles are best suited for herbicides, liquid fertilizer and a mix of both applications. Ceramic flood nozzles thanks to the exceptional wear resistance can be used to spray suspension fertilizers.
Cone Pattern Nozzles
- Full Cone Nozzles produce drift prone, fine sized droplets in a circular shaped pattern that fills an entire circle. They are ideal for spot spraying and are mainly used when applying high volumes of pesticides. A greater output can be produced with a two piece, Disc & Core, rather than one piece solid cone nozzle. Two piece nozzles can be used at higher pressures (10 to 500 psi) while one piece are used at lower pressures (20 to 60 psi). Full cone nozzles have spray angles ranging from 30° to 120° with narrower angles offering the best foliage penetration. However, wider spray angles operated closer help reduce drift.
- Hollow Cone Nozzles also produce a circular pattern, but the spray is concentrated at the outside of the circle with none in the center. Hollow cone nozzles are designed to swirl the spray around in a cone shape. This is obtained through the use of two parts, a core or swirl/whirl plate, and the nozzle tip or orifice disc. The core has 2 or 3 holes or slots that are cut at an angle. As the liquid is forced through the whirl plate/disc it causes the liquid to rotate or swirl. The rotating liquid then flows through the nozzle orifice and forming a hollow liquid cone. The thickness of the sheet of liquid gradually decreases as the cone shape spreads out, and individual droplets are eventually formed when the surface etnsion of the liquid is broken. Traditionally, hollow cone nozzles are sold as a two piece version : Disc & Core. However, newer one piece designs incorporate both parts into one sealed piece which is easier to use and less likely to break.
Hollow cones produces a finely atomized spray, generally finer and more uniform than full cone nozzles. This unique pattern provides complete coverage.
Hollow cone nozzles can be used with wettable powders, flowables, and suspensions, and are best suited for applications that need good coverage like contact insecticides, fungicides and growth regulators.