Flat Fan Spray Nozzles
Lechler flat fan nozzles produce a sharply defined, linear spray pattern. Uniform liquid distribution, high impact, and a wide selection of spray angles are characteristic features. Specific industrial applications are met through variations in nozzle design, accounting for liquid flow, spray velocity, spray pattern profile, and spray pattern coverage. Lechler offers two designs of flat fan nozzles: axial and deflector.

Axial flat fan nozzles utilize a straight-through flow design with an elliptical orifice. This design offers the widest selection of spray angle, flow rate and configuration.

Distribution
Flat fan designs fall into two categories: Tapered (a.k.a. parabolic) and even. These terms describe the distribution of liquid across the width of the spray coverage.

Tapered — These designs deliberately make the flow heavier in the center of the width and it tapers off as you approach the edges. This allows you to overlap the nozzles when making headers so that the spray across the whole header will be very even. The diagram shows how the coverage should be overlapped for optimum performance. Tapered distribution nozzle series are indicated by this symbol on the edge of the page:

Even — These designs distribute the liquid evenly across the full width of the spray. This is best when using only one or two nozzles for a specific application. When designing headers, if the overall coverage is critical, the overlap should either be 0% or 50% on each side. Even distribution nozzle series are indicated by this symbol on the edge of the page:

Free Passage
If you are concerned that your liquid supply is contaminated with solids that could clog your nozzles, you can determine the probability of this happening by checking the free passage measurement of the nozzle you are using. The table indicates all the capacities available over all our tapered distribution product lines. (The section labeled “Second Tier” applies to series that change numbers, such as 670’s which become 671’s in the larger capacities.)

You will note that the standard angles are shown for each capacity as you read across the table. The measurement indicates the largest spherical object that will pass through the orifice. (This is roughly the minor axis of the elliptical orifice. Some of these have been rounded and are not meant to indicate an exact measurement of a specific orifice.) If you are trying to decide if you need to add a strainer or filtration, follow the rule of thumb that to ensure clog free operation, you should not have any solids in the line larger than one third the free passage of the nozzle. If you do, an appropriate filtering device is in order.

Spray Angle vs Spray Width
Many of the flat fan catalog pages have charts which indicate “Theoretical Spray Width.” This is to provide a coverage estimate for the width of the spray at a given distance. This is only an estimate, as the trajectory of the droplets will change due to gravity and ambient air movement. Depending on the distance from the orifice, spray direction, droplet size, droplet velocity and air movement, the character of the spray can change substantially. In very critical applications, only an actual test will give reliable data.