FLAT FAN SPRAY NOZZLES
Flat fan spray nozzles are one of the most common nozzles in use today and are available in many materials and numerous spray angles. The pattern generated by this type of nozzle concentrates the fluid in a thin line. Spray nozzle design and precision machining have a significant effect on the stability of the spray pattern and impact achieved. The impact produced is related to the operating pressure, distance to the point of impact, as well as the nozzles spray angle.
There are two basic types of flat spray nozzles defined as axial and deflector configurations. The axial design provides a spray pattern axial to the orifice. The deflector design utilizes a deflector shield/plate to form the flat fan spray pattern which is usually between 20 to 30 degrees offset from the exit orifice. Deflector designs tend to be more clog resistant due to their round orifice versus the axial design which uses a drill/mill operation producing a "cats eye" type orifice. Generally speaking the deflector designs tend to produce less impact at equivalent flows/pressure. The narrower the spray angle, the greater the impact at a given distance. Therefore narrower spray angle nozzles are used for difficult cleaning applications whereas wider angle nozzles are used for less intensive washing and rinsing.
There are two types of axial flat spray patterns, some have tapered (cats eye) patterns and others (flat fan even spray) provide a more uniform distribution. The most popular type has a tapered spray distribution and the diagram above shows overlapping the nozzles by about 30%. This is because the edges of the spray have less flow than the center portion and the overlapping of the spray patterns help equalize the flow distribution across the target. It is suggested that nozzles in a spray header be offset by 5 to 10 degrees so their patterns do not intersect prior to impacting the target.