Sprinkler Nozzles

A sprinkler nozzle turns mains or pump pressure into a pattern of droplets spread across a fixed radius. The job looks simple until you try to make every head in a zone throw the same distance on the same pressure, then radius, arc and trajectory stop being catalogue trivia and become the difference between even coverage and a lawn with brown rings.

This is the irrigation and greenscape side of spray nozzles: lower pressure than process duties, larger throw distances, and a pattern chosen for ground coverage rather than surface wetting.

Radius, Arc and Trajectory

Radius is how far the wetted pattern reaches, set by the nozzle orifice and the supply pressure. Two heads on the same zone must throw the same radius or the overlap is wrong and you get dry wedges.

Arc is the sector the head covers, full circle for open areas, fixed or adjustable partial arcs for corners and edges. Mixing arc types without rebalancing flow is the usual cause of a zone that over-waters one spot and starves another.

Trajectory is the launch angle. Low-trajectory nozzles throw under wind and past obstacles; high-trajectory types clear taller crop or shrub but drift more in wind. The choice is set by what is between the head and the ground it has to cover.

Fixed Spray Versus Rotary

Fixed-spray (sometimes called spray) nozzles throw a continuous fan or cone out to a short radius, typically a few metres. They suit small zones and tight layouts but need higher pressure to hold the pattern and lose a lot to evaporation on hot days.

Rotary (rotor) nozzles throw streams that rotate, covering a much larger radius at lower pressure per unit area. They are the right call for larger turf and for water-efficient design, because the slower application rate lets the soil absorb instead of running off.

The mistake is fitting rotary heads into a small zone designed for fixed spray, or vice versa, the radius and precipitation rate no longer match the pipe and the pressure.

Matching to Water Pressure

Sprinkler nozzles are rated at a reference pressure (commonly 2 bar) and radius falls as pressure drops. A zone supplied by a weak pump throws short and develops dry rings; the fix is usually a pressure-regulated header or a smaller-orifice nozzle set, not a bigger pump.

Flow scales with pressure, so a pressure swing also changes how much water each zone draws, relevant wherever the supply is metered or shared with other uses.

Range Walkthrough: What Each Model Is For

The reference table above lists the range in one view; this section says when each model is the right answer.

SK-1 (full circle, 2–4 m): the short-radius end of the range, for small beds, orchard under-tree lines, greenhouse benches and nursery strips where the throw has to stay inside a small planted area. Flow of 0.05–0.3 m³/h at 2 bar keeps the precipitation rate low enough for slow infiltration, and the 1/2“ connection drops straight into both micro and conventional lines. PP/ABS suits clean irrigation water.

SK-2 (full circle, 4–7 m): the mid-radius full-circle head for open patches of lawn, vegetable blocks and row-crop strips where the full 360° pattern is wanted. The 0.15–0.7 m³/h flow band at 2 bar sits where the small-rotor and rotary-stream classes normally work, and the 15–25° trajectory clears low crop without climbing over hedges. The natural step up when SK-1 throws too short.

SK-3 (adjustable arc, 5–9 m): the corner-and-edge head. The adjustable arc lets one model serve full, half and quarter patterns, so a zone with borders, paths and building lines can be matched without stocking three part-circle nozzles. Flow of 0.25–1.2 m³/h at 2 bar with an 18–25° trajectory covers the lawn-size bracket where geometry, not coverage, is the problem.

SK-FC (fixed spray, 1.5–3 m): the classic spray head for tight layouts: small gardens, borders and strips where a rotary would overshoot. The short throw keeps zone pipework and head spacing small. Fixed sprays apply water faster, precipitation rate typically in the 10–15 mm/h band, so run times are short and the pattern is a clean, even fan. PP body, 1/2“ connection.

SK-RB (rotary, 8–12 m at 2 bar): the big-radius head for turf, sports fields, parks and dust-suppression duty. The 3/4“ connection and 0.3–1.8 m³/h flow feed a rotating stream that covers far more ground per head than any fixed spray, at a lower application rate the soil can absorb. Nylon internals give it more wear resistance in gritty water than the PP models.

Application Matrix

Application	Typical duty	Recommended model	Why
Residential lawns	Small to medium turf zones	SK-3 or SK-RB	Adjustable arc fits odd shapes; rotary keeps PR low
Sports fields and parks	Large open turf, even cover	SK-RB	8–12 m radius, few heads, uniform precipitation rate
Row crops	Field and vegetable irrigation	SK-2	Full-circle mid throw, 15–25° clears the crop
Orchard and nursery	Under-tree and bench lines	SK-1	2–4 m throw stays inside the canopy, low flow
Greenhouse	Bench and pot watering	SK-FC or SK-1	Short fixed throw, even fan, easy to keep off walkways
Landscape beds and borders	Shrubs, hedging, narrow strips	SK-FC	1.5–3 m fixed spray fits tight layouts
Dust suppression	Stockpiles, yards, haul roads	SK-RB	Long coarse throw covers the pile; PR precision less critical
Construction and demolition	Damping down dust on site	SK-2 or SK-RB	Mid to long throw onto rough, uneven terrain

Each row is the same decision in miniature: radius to cover the area, flow to match the zone, and a trajectory that clears what stands in the way.

Three-Step Selection

If the full checklist below feels heavy, the decision collapses to three questions:

1. How far? Radius sets the model bracket. Under 3 m → SK-FC or SK-1; 2–4 m → SK-1; 4–7 m → SK-2; 5–9 m with corners and edges → SK-3; over 8 m of open ground → SK-RB. Nothing else matters until the throw is right.
2. How much flow? Match the m³/h at 2 bar to what the zone can supply and to the precipitation rate you want. Fixed sprays apply roughly 10–15 mm/h and run short cycles; the full-circle and rotary models sit around 3–8 mm/h and run longer. If the pressure at the head is weak, stay at the low-flow end of the bracket, a smaller-orifice nozzle throws more reliably than a starved large one.
3. Which trajectory? Low angles (15–20°) for windy sites and low obstacles; the standard 25° band where nothing stands between the head and the ground; the rotary’s 10–25° span covers both. Crop height and wind decide it.

Reference Specifications

Radius and flow below are quoted at 2 bar with clean water. Trajectory is the launch angle class. The 15 m figure on the rotary is the maximum of the envelope and needs 3–4.5 bar, the 2 bar working radius is 8–12 m.

How to Select a Sprinkler Nozzle

• Zone size and shape: sets radius and arc; match every head in the zone to the same radius.
• Supply pressure at the head: not at the pump; friction loss in the pipe matters.
• Fixed spray versus rotary: small tight zones favour fixed spray, large turf favours rotary for efficiency.
• Trajectory versus obstacles: low for wind and clearance, high for taller crop.
• Precipitation rate balance: all heads in a zone should apply water at the same rate or some areas flood while others dry.
• Maintenance reality: screens clog with grit; a dirty screen throws short and creates the dry ring people blame on the nozzle.

Frequently Asked Questions

Why does my sprinkler zone have brown rings? Almost always a radius mismatch or a clogged screen dropping pressure at one head. The pattern is telling you the heads are not throwing the same distance.

Fixed spray or rotary for a small lawn? Fixed spray for small, tightly laid-out zones; rotary for anything large enough that the lower application rate and bigger radius save water.

Why does radius drop on hot afternoons? Evaporation loss on fixed-spray nozzles, plus any pressure sag from simultaneous use. Rotary nozzles suffer less because they apply more slowly.

Can I mix arc types in one zone? Only if you rebalance flow and radius so every head still wets the same area at the same rate. Unbalanced arcs are a common over/under-watering cause.

What pressure do sprinkler nozzles need? Most of the range is rated at 2 bar, that is where the radius and flow figures above are quoted. The rotary is the exception: it reaches 12 m at 2 bar but needs 3–4.5 bar for the full 15 m. Below the rated pressure, radius shrinks and the overlap between heads opens into dry wedges.

How much water does each nozzle use? At 2 bar, the full-circle and fixed-spray models draw 0.05–0.3 m³/h (roughly 1–5 L/min), the mid models 0.15–1.2 m³/h, and the rotary 0.3–1.8 m³/h (5–30 L/min). Flow rises with the square root of pressure, so a pressure swing changes both radius and the zone’s total water use.

Which material should I choose? PP and ABS cover most clean irrigation water. For the rotary on gritty or sandy supply, the nylon internals wear better than the plastic models, a worn orifice enlarges, flow creeps up and the zone over-waters without anyone changing a setting.

What is the difference between full-circle and adjustable-arc models? Full-circle heads (SK-1, SK-2) wet a complete 360° pattern and suit open areas. The adjustable-arc SK-3 lets you set the sector, full, half, quarter or a wedge, so corner and edge heads deliver the same depth as the full-circle heads in the middle of the zone, instead of wasting water against a wall or path.

If you are laying out a new zone or fixing one that floods on one side and browns on the other, the sprinkler nozzle selection guide walks through the precipitation-rate math, and the enquiry form takes your pressure, zone size and layout for a full sizing.