Glossary
Spray pattern
Definition
Distribution of the fuel inside the spray cone — solid, hollow, or adapted to the character of the combustion head.
The spray pattern describes how the fuel is distributed inside the cone. A solid pattern fills the cone evenly; a hollow pattern concentrates the fuel at the outer edge and leaves the centre thin. Which one is wanted is decided by the flame shape the burner needs.
The pattern is not independent of the angle or of the flow rate. A nozzle that produces a clean hollow cone at its rated output may show a partly solid cone at low output. That is why the burners in the Fluid Control Instruments Ltd range are matched to the combustion head rather than to a generic pattern.
On the simplex atomizer the pattern is set by the swirl chamber and by the orifice length. On the spill-back, disc and air/steam atomizers the pattern is adapted to the character of the combustion head, so the flame fills the flame tube without impinging on the walls.