Quick answer: Spray angle is the angle formed by the spray pattern as it leaves the nozzle orifice, measured in degrees (common values: 15°, 30°, 65°, 80°, 90°, 110°, 120°). It directly determines how wide the spray spreads at a given distance from the nozzle. A wider angle covers more area at the same mounting height but delivers less impact per unit area; a narrower angle concentrates flow into a smaller area with higher impact.
How Spray Angle Determines Coverage Width
Spray angle and mounting distance together set the coverage diameter (for full/hollow cone) or coverage width (for flat fan). The estimating formula is:
Coverage width = 2 × Distance × tan(Angle ÷ 2)
Worked example: A nozzle rated at 80° is mounted 12 inches from the target.
Coverage width = 2 × 12 × tan(40°) = 2 × 12 × 0.839 = ≈ 20.1 inches
Move the same nozzle to 24 inches, and coverage roughly doubles to about 40 inches — because coverage width scales directly with distance at a fixed angle. This is why header height and spray angle have to be selected together, not independently.
Why the Same Angle Behaves Differently by Nozzle Type
| Nozzle Type | What the Angle Describes | Practical Implication |
|---|---|---|
| Full cone | Cone diameter at the target plane | Wider angle = more area, but coverage density thins toward the edge |
| Flat fan | Width of the flat spray “fan” | Wider angle = wider swath per nozzle, useful for header spacing |
| Hollow cone | Diameter of the ring-shaped pattern | Center of the pattern stays dry; angle sets the ring’s outer diameter |
| Spiral | Cone diameter, similar to full cone | Large free-passage design tolerates angle variation under fluctuating pressure |
Spray Angle Isn’t Fixed — Pressure Changes It
Published spray angle is measured at a specific test pressure. As covered in how flow rate and pressure are related, raising pressure typically widens spray angle up to a point, after which it can plateau. If your actual operating pressure differs significantly from the catalog test pressure, expect the real-world angle — and therefore coverage — to shift somewhat from the published number.
Practical Recommendations
Match spray angle to mounting distance before ordering, not after installation — moving a header a few inches later is far more disruptive than checking the geometry up front. For applications needing uniform coverage across a wide surface (tank cleaning, dust suppression headers), multiple narrower-angle nozzles with overlapping patterns are usually more predictable than a single very wide-angle nozzle, because overlap uniformity is easier to control than edge-of-pattern thinning on one large cone.
Common Mistakes
A frequent error is selecting spray angle based on the coverage needed at the nozzle’s rated test distance without checking the actual mounting height in the application — the same nozzle can look like it covers a target perfectly on a datasheet and fall short (or overshoot) once mounted at a different distance. Another common mistake is assuming angle is fixed regardless of pressure, then being surprised when a pressure change made during commissioning also shifted the coverage pattern.
FAQ
What is the difference between an 80-degree and a 110-degree spray nozzle?
The angle number describes how wide the spray pattern opens. A 110° nozzle produces a wider spray at the same mounting distance than an 80° nozzle, but typically with lower impact per unit area since the same flow is spread over more surface.
How do I calculate spray coverage from angle?
Use Coverage width = 2 × Distance × tan(Angle ÷ 2). Multiply the tangent of half the spray angle by twice the mounting distance to estimate coverage width or diameter.
Does spray angle change with pressure?
Yes, in most nozzle designs. Angle is published at a fixed test pressure; operating at a different pressure can widen or narrow the real-world pattern.
Related reading: full cone nozzles, flat fan nozzles, and Flat Fan vs Full Cone Nozzle guide. Want to plan header spacing next? See nozzle spacing and overlap guidance.