Choosing the right spray nozzle made easy

 

Choosing the wrong spray nozzle can be a costly mistake.

Improper nozzle selection can be expensive if re-spraying is required, performance is reduced or legal issues arise as a result of chemical drift. Take a few minutes to review your spraying requirements, and be prepared to have multiple nozzle sets on hand to meet your needs.

Spray nozzles are highly engineered, precision components.

Even a spray nozzle with only 10% wear may not give you the coverage and performance you require. The cost of replacing nozzles is minor compared to the consequences of poor spraying.

The spray nozzle you select will determine:

• Amount of chemical applied to an area
• Uniformity of the application
• Coverage of the chemical on the target surface
• Amount of potential drift

Three common types of spray nozzles include:

Droplet size is a key factor in nozzle selection:

The ASABE (American Society of Agricultural and Biological Engineers) S572.1 standard uses eight droplet classifications ranging from extremely fine to extremely coarse. Keep in mind that droplet size decreases as your sprayer pressure increases.

• Fine droplet sizes are used for contact fungicides and insecticides or contact herbicides that require adequate retention on leaves.
• Medium droplet sizes are the most widely used and are typically good for systemic herbicides, insecticides and fungicides.
• Coarse droplet sizes are used with systemic, residual and soil-applied herbicides or to minimize spray drift.

How to Identify Spray Nozzles

Nozzles have markings that will identify their performance specifications, including spray angle, flow rate and material. The color will also identify its flow rate at 40 psi. Red nozzles, for example, have a flow rate of 0.4 gallons per minute at 40 psi. These colors are different than the ones used to classify droplet size.

1. What are you spraying?

Read the pesticide label to determine the type of nozzle, its application rate, required droplet size, nozzle spacing and environmental restrictions.

2. How are you spraying?

Different types of nozzles are available for broadcast, banded, directed or mechanical air-assisted spraying.

3. What is your tolerance to drift?

You may need to consider low-drift spray nozzles if there is a chance your application could drift away from its target.

Tips to control drift

• Reduce pressure to increase droplet size
• Use drift reducing nozzles or larger capacity nozzles that produce larger spray droplets
• Lower boom height
• Pay attention to weather conditions and adjust application methods accordingly

4. What is the weight of the spray solution?

Nozzle specifications are based on water, so you may need to use a conversion factor if spraying something that is heavier or lighter.

5. What is the pressure range of the sprayer?

Selecting a nozzle in the middle of your sprayer's operating range will provide flexibility if you need to make adjustments to speed.

6. What is the nozzle spacing on the boom?

Manufacturers recommend optimal nozzle spacing for each nozzle type and spray angle. 20" and 30" spacing are most common.

7. What is the boom height?

Lower boom heights reduce drift and improve coverage. 110° nozzles can typically be used at lower boom heights than 80° nozzles.

8. What is your sprayer speed?

You'll get done spraying faster at higher speeds, but spray drift and canopy penetration improve at lower speeds.

9. Which nozzle material is best?

Nozzle material will depend on the chemical being sprayed and your budget. Materials such as ceramic may be more expensive initially, but cost less in the long run because they wear longer. Never mix different nozzles or materials on your boom.

• Brass is the least durable nozzle material
• Plastic lasts two to six times longer than brass
• Stainless steel lasts four to six times longer than brass
• Ceramic lasts 20 to 50 times longer than brass

Once you pick a nozzle, use its application table to pick a color. Don't see the nozzle you need? Give us a call and we'll help you find it.