1.3.1 Sprinkler Nozzle Application Patterns

A good sprinkler distribution profile will have a greater depth of application near the sprinkler head and the profile will decrease in a reasonably uniform rate to the most distance point of throw. Well spaced overlapping sprinklers will place the high application rate of sprinkler A about at the point of the lowest application rate of sprinkler B. An overlap of 40% to 60% as described previously gives this pattern. Summing up the contribution of all sprinklers will show a profile of a uniform total application.

A poor sprinkler distribution profile will have, for example, a high application rate both close to the sprinkler head and at its outer radius and a low application rate in between. This profile makes it difficult to overlap sprinkler profiles to get a uniform pattern.

Figure 1.3.1a Nozzle application patterns are subject to the water pressure at the nozzle. Illustrated here are typical patterns for a range of pressures. Each nozzle has a recommended pressure range at which it should be operated so overlapping nozzles give a fairly uniform application pattern.

 

Pressure has a major influence on the distribution pattern. As shown in Figure 1.3.1a, too high a pressure causes the water stream to break up into very fine droplets or mist that falls close to the sprinkler head. Too low a pressure causes the water stream to flow out without breaking up very much so it forms a donut-shaped ring around the sprinkler head of higher water application.