Types of Spray Nozzles and How to Choose the Right One

FBN Network

May 10, 2024

Selecting the right sprayer nozzle for your needs involves considering several factors to ensure effective and efficient application of liquids, such as pesticides, herbicides, and fertilizers. The right nozzle will help you achieve your desired application rate, droplet size, and coverage while minimizing spray drift and waste. 

Here's how to choose the right nozzle based on your specific needs.

1. Plan the Application Rate

Start by determining the desired application rate, usually expressed in gallons per acre (GPA). This rate depends on the product being applied and its label recommendations.

How to Read a Chemical Label

2. Select the Nozzle Size

Next, use the following formula to calculate the nozzle size needed to achieve the desired application rate you planned above.  

Nozzle manufacturers provide detailed charts that show the output (GPM) for their nozzles at various pressures. Once you have calculated the required GPM for your upcoming spray, consult these charts to select a nozzle size that meets your needs at an operational pressure that is within the recommended range for the nozzle.

If a specific nozzle size is not available, try changing the travel speed and determine the new flow rate needed.

Nozzle Size Charts

Click on the links below to download a high-quality PDF of each nozzle size chart.

How to Calculate Your Nozzle Size

If you’re not using a manufacturer-provided chart, you’ll need to review a few factors to determine the right nozzle size. Start by determining the nozzle flow rate at gallons per minute (GPM). To find that figure, use the formula below: 

GPM = [GPA x MPH x W] / 5940

  1. Start with your application rate in gallons per acre (GPA). 

  2. Find an efficient and safe ground speed in miles per hour (MPH). 

  3. Determine the spray width per nozzle (W), keeping in mind that different types of spray methods will require different spray widths (W):  

  • Band spraying: W = band width in inches

  • Broadcast applications: W = nozzle spacing (distance between two nozzles on the boom) in inches

  • Directed spraying: W = row spacing in inches (or band width) divided by the number of nozzles per row (or band)

The constant 5940 is used to convert the units appropriately (1 acre = 43,560 square feet, and there are 60 minutes in an hour).

Spray Width 

Spray width per nozzle is determined by the: 

  • Spacing of the nozzles on the boom 

  • Spray angle

Nozzle Spacing on the Boom

The spacing of the nozzles on the boom is an important consideration for achieving uniform coverage by ensuring that the spray pattern from each nozzle overlaps sufficiently, minimizing gaps and avoiding areas of under- or over-application. 

Here's how to determine the spacing of the nozzles on the boom:

  • Determine your desired overlap, which is based on the type of application and the product being sprayed. Common overlap percentages range from 30% to 50%. For example, let's assume a desired overlap of 40%.

  • Calculate the effective spray width per nozzle by dividing the actual spray width per nozzle by the overlap percentage. For example, if the actual spray width per nozzle is 20 feet, the effective spray width per nozzle would be 20 feet / 0.4 (40% overlap) = 50 feet.

  • Determine the desired spacing between nozzles on the boom based on the effective spray width per nozzle. For example, if the desired effective spray width per nozzle is 50 feet, and you want to achieve a 20-inch spacing between nozzles, divide the effective spray width per nozzle by the desired spacing: 50 feet / (20 inches / 12 inches/foot) = 30 nozzles.

  • Consider boom height above the target surface — higher boom heights may require narrower nozzle spacing to maintain the desired coverage — and adjustable mounting options. Some nozzle bodies allow for adjustable spacing, allowing you to fine-tune the nozzle spacing based on your specific needs.

  • Adjust for specific conditions as needed. For example, applications in dense crop canopies, such as row crops, you should consider using narrower nozzle spacing to ensure better coverage and penetration. Wider spray angles may require wider nozzle spacing, while narrower spray angles may require narrower spacing.

Spray Angle

The spray angle determines the width of the coverage area. Wider angles cover more area with a single pass, which can reduce the time and fuel needed for application. Smaller spray angles produce larger droplets that are less prone to drift but may provide less coverage and canopy penetration.

The spray angle affects how nozzles should be spaced on the boom and the optimal height of the boom above the target. Proper overlap between passes is essential for uniform application. 

When to Use Different Spray Angles
  • Wide Angles (e.g., 110° to 120°): Ideal for herbicide application where broad coverage is needed. These angles allow for lower boom heights, reducing drift risk.

  • Narrow Angles (e.g., 80° to 95°): Better for targeted applications, such as in row crops where you want to minimize off-target deposition. They are also useful when higher boom heights are necessary, although they may increase the risk of drift.

4. Select Droplet Size and Spray Pattern

Next, consider the recommended droplet size for the product being applied. When selecting sprayer nozzles, understanding the relationship between droplet size and the nozzle's characteristics is essential for achieving optimal application results. 

Droplet Size Categories

Droplet sizes are generally categorized as follows:

  • Ultra Fine (<100 microns): Prone to drift, often used for fogging applications.

  • Fine (100-200 microns): Higher drift potential, but good for systemic herbicides where coverage is less critical.

  • Medium (200-300 microns): Balanced between drift management and coverage, suitable for most contact herbicides.

  • Coarse (300-400 microns): Lower drift potential, good for soil-applied herbicides and when drift needs to be minimized.

  • Ultra Coarse (>400 microns): Very low drift, used for applications where drift control is paramount.

Droplet Impact on Nozzle Selection

When selecting nozzles, consider the following aspects related to droplet size:

  • Application Type: The type of chemical being applied (e.g., herbicide, fungicide, insecticide) often dictates the desired droplet size. Contact fungicides and insecticides often require finer droplets for better coverage, while systemic herbicides may work better with coarser droplets to minimize drift.

  • Drift Management: In areas where sensitive crops or habitats are nearby, choosing nozzles that produce larger droplets can help minimize drift and protect non-target areas.

  • Pressure: The pressure at which the nozzle operates also affects droplet size. Higher pressures generally produce smaller droplets, while lower pressures produce larger droplets. However, each nozzle type has an optimal pressure range for desired droplet size and application efficiency.

  • Weather Conditions: Wind speed and temperature can influence droplet evaporation and drift. On windy days or when applying volatile substances, larger droplets may be preferable to reduce off-target movement.

Regular calibration of your sprayer and nozzles is essential to ensure that the desired droplet size is being achieved consistently.

Additionally, new technologies, such as pulse width modulation (PWM) systems, allow for more precise control over droplet size and application rates, even at varying speeds and conditions.

Different nozzle types, which create different spray patterns and associated shapes, produce different droplet sizes. Once you have calculated the required nozzle output, select a nozzle type that provides the desired spray shape and droplet size at that output.

Shape of the Spray Pattern

The spray shape affects how uniformly the spray is distributed across the target area. Even distribution is crucial for avoiding areas of under- or over-application. The spray pattern can influence droplet size, with certain shapes producing finer droplets that are more susceptible to drift and evaporation.

Certain shapes are also better suited for specific targets. For example, a flat fan pattern is ideal for surface applications, while a cone pattern may be better for foliar applications where canopy penetration is important.

Types of Spray Nozzles

Though there are many spray nozzles types and sizes, there are three basic types of spray nozzles:

Flat Fan

Flat fan nozzles are recognized by their mountain-shaped spray pattern and even distribution. They are good for:

  • Spraying water or chemicals

  • Cleaning

  • Cooling

Hollow Cone

Hollow cone nozzles are recognized by their donut-shaped spraying pattern. They are good for:

  • Spraying water or chemicals

  • Cooling and washing gases

  • Humidifying and chemical reactions

Full Cone

Full cone nozzles are recognized by their cone-shaped spraying pattern. They are good for:

  • Spraying water or chemicals

  • Cleaning

  • Cooling

Each one has specific characteristics and applications.

When to Use Different Shapes:

  • Flat Fan: Most common for herbicide application, providing good coverage and uniformity on the ground or plant surfaces.

  • Even Flat Fan: Designed for uniform application of chemicals across the spray width, minimizing overlap errors.

  • Cone (Full Cone and Hollow Cone): Useful for insecticides and fungicides where canopy penetration is necessary. Full cone patterns provide denser coverage, while hollow cone patterns are better for penetrating dense foliage.

  • Stream: Used for direct application of fertilizers to the soil or for systemic treatments that need to reach the plant base without foliar contact.

Common Nozzle Patterns

5. Adjust for Specific Conditions

In areas prone to wind, consider using nozzles that produce larger, less drift-prone droplets or include drift-reducing technology.

For applications requiring canopy penetration, such as fungicides in dense foliage, select nozzles that produce smaller droplets and have a spray pattern designed for penetration.

6. Conduct Field Testing

After selecting nozzles, conduct field tests to verify that the application rate and coverage meet your expectations. Adjust nozzle selection or operating parameters as necessary.

By carefully considering these factors and performing calculations based on the specific conditions and requirements of your application, you can select the appropriate nozzle size for your agricultural use case. 

Selecting the right nozzle based on spray angle and pattern shape is essential for effective pest and disease management, optimal plant growth, and minimizing environmental impact. It's also important to consider other factors such as the type of chemical being applied, the target crop or pest, environmental conditions (e.g., wind speed), and equipment capabilities when choosing nozzles. 

Stock Up for Spraying Season with FBN®

FBN Direct offers a wide range of products to support your upcoming spray needs. Learn more by exploring available crop protection products or use the interactive AcrePlan tool to customize your ag chem volumes to your specific application needs. 

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FBN Network

May 10, 2024