Selecting and maintaining your spray nozzles

Although nozzles are some of the least expensive components of a sprayer, they hold a high value in their ability to influence your sprayer performance. Nozzles meter the amount of liquid sprayed per unit area, thus controlling application rate. Nozzles also influence droplet size, affecting both target coverage and spray drift risk.

Whether you are treating a cockroach, mosquito, flea, ant, or any other pest infestation, the way you spray makes a signification difference. Spray nozzles give you the flexibility to treat specific areas, while also creating an effective, long-lasting solution. Nozzles come in a wide variety of types and sizes. The best nozzle for a given application will maximize efficacy, minimize spray drift, and allow compliance with label requirements.

NOZZLE TYPE

Each nozzle type is designed for a specific type of target and application. For example, a nozzle designed for broadcast spraying through a boom sprayer is not effective for spraying pesticides over a narrow band.

Spray Pattern.

This is the actual pattern of the liquid as it is applied to the surface. The most common spray patterns used in professional pest control to treat surfaces are fan, cone, and pin stream. It is critical to use a proper spray pattern to ensure optimum distribution.

Fan Spray.

This spray pattern is used most commonly in pest control applications because it provides the best distribution of the liquid on the substrate. The flat fan spray pattern is best suited for treating flat surfaces, both horizontal and vertical; the width of the spray pattern can be 18-24 inches depending on the spray angle of the orifice. Because the majority of the liquid is delivered in the centre of the pattern, overlapping the swath by about one third will result in optimum coverage of the surface.

Cone Spray.

There are basically two types of cone spray nozzles in common use. One has a fixed out-put volume and spray pattern, the other is an adjustable cone nozzle. In the latter the spray pattern can be adjusted from a cone pattern to solid stream. Cone spray nozzles were originally designed for agricultural use, to spray over the top of plants to get complete coverage. They are generally not suitable for treating flat surfaces, and their use can result in over-application of insecticide.

• Fixed capacity cone nozzle – Most commonly used when a small droplet size and low application rate is required. The benefit of this type of nozzle is that the spray pattern and delivery rate are fixed and cannot be changed by the operator.
• Adjustable cone nozzle – This is most commonly found on inexpensive hand and backpack sprayers. These nozzles can be adjusted from a cone spray to pin stream; however, the result of small adjustments can be a large change in delivery rate and spray pattern.

Pin Stream.

This type of spray tip is typically used for crack and crevice applications where a concentrated stream of insecticide is directed at a specific area, such as a harbourage for cockroaches or ants. The delivery rate for pin-stream orifices can be nearly equal to that of a fine fan or half the rate of a coarse fan orifice. The crack and crevice straw is the modern equivalent of the classic pin stream orifice. These plastic straws extend the pin stream opening several inches so that the inside of a crevice can be treated with precision and without the splash and waste of insecticide. These may also be referred to as solid stream nozzles.

Just like any other part of the sprayer that comes in contact with spray solutions, nozzles along with filters should be cleaned regularly. The best way to do that is to dilute any residues via a series of rinses in clean water. For a more rigorous cleaning, one of the intermediate rinses should include a detergent or equipment cleaner, and soaking during this step is an excellent practice.

The orifice of any nozzle is delicate, either machined or moulded to exacting standards. Even small changes to the orifice shape results in distorted spray, a change to the rate and a change in the droplet size. If foreign objects or residues remain in the tips, the subsequent spray job may be less accurate and even damage the tips.
Take the opportunity over the quieter months to clean and inspect your spray tips for damage so the sprayer is ready for use when business picks up.

Here’s a step-by-step guide to cleaning nozzles:

• Wearing gloves, remove all nozzles, strainers, rubber gaskets and tips from the sprayer.
• Put them in a large plastic pail and cover them in warm water. Leave them to soak.
• Drain the pail, but be aware that the rinsate will have pesticide residue.
• Re-fill the pail with a solution of detergent or equipment cleaner.
• With a soft toothbrush, scrub the caps, gaskets, strainers and nozzles to remove any residue. Some nozzles can be pulled apart to expose the mixing chamber.
• After scrubbing, leave all the parts to soak in the detergent solution.
• Drain the solution, which will contain trace amounts of pesticide, rinse the parts with water and reassemble the nozzles.

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