Spray Head Performance Charts

The “Spray Head Performance Charts” page provides essential information to help you calculate the Gallons Per Minute (GPM) for your pop-up spray heads, giving you a clear baseline for your irrigation system’s water usage.

To ensure accurate results, it’s critical to verify that all spray heads in a zone have a matched precipitation rate, which can be achieved by using nozzles from the same manufacturer, such as RainBird or Hunter. Manufacturer-specific nozzle charts are a valuable resource, offering precise data for different nozzle lines.

This guide empowers you to optimize your irrigation setup for even and efficient water distribution.

How to Use the Spray Head Performance Chart

Identify the Spray Nozzle Series: Select the spray nozzle series based on the radius of coverage needed (e.g., 5-foot, 8-foot, or 15-foot). This information is typically marked on the nozzle or available in the manufacturer’s documentation.
Determine Optimal Pressure (PSI): Check the chart for the recommended operating pressure (usually 30 PSI for most spray nozzles) to ensure proper function and water distribution.
Measure the Radius of Coverage: Match the desired spray radius to the corresponding nozzle in the chart. This ensures that the spray head delivers water to the intended area without overshooting.
Calculate GPM Flow Rate: Find the GPM for the selected nozzle and radius under the optimal PSI. This value represents the water flow rate for one spray head.
Account for Matched Precipitation Rate: Ensure all nozzles in the zone are from the same manufacturer and nozzle line to maintain a matched precipitation rate, meaning the entire zone receives uniform water distribution.
Determine Total GPM for the Zone: Multiply the GPM of a single spray head by the total number of spray heads in the irrigation zone. This helps in selecting the right pipe size and pressure regulator for the system.

FAQs About Spray Head Performance Charts

1. What is a matched precipitation rate, and why is it important?
Matched precipitation rate means all nozzles in the zone deliver water at the same rate, regardless of their spray radius or arc. This ensures even watering across the landscape, preventing dry spots or water pooling.

2. Can I mix nozzles from different manufacturers in the same zone?
No. Mixing nozzles from different manufacturers can result in mismatched precipitation rates and uneven water distribution. Stick to nozzles from the same brand and nozzle line.

3. How do I calculate the precipitation rate (PR) for my zone?
Use the formula: PR $= (96.3 \times Total GPM)/ Zone Area in Square Feet$

This gives you the precipitation rate in inches per hour, which is crucial for scheduling run times.

4. What do I do if my system has inconsistent pressure?
Install a pressure regulator to ensure consistent pressure across the system. Inconsistent pressure can cause uneven spray patterns and reduce the efficiency of your irrigation.

5. How often should I inspect my spray heads?
Inspect your spray heads monthly during the irrigation season to check for clogs, leaks, or misaligned nozzles. Regular maintenance ensures optimal performance.

6. Can spray heads work on sloped areas?
Yes, but use pressure-regulated heads and check valves to prevent water from pooling at the base of the slope. Adjust nozzle settings to account for elevation changes.

7. What do the strip nozzles in the chart cover?
Strip nozzles are designed for narrow, rectangular areas such as medians or flower beds. Their dimensions (e.g., 4×15 or 4×30) indicate the width and length of coverage.

Additional Tips for Spray Head Performance

Test Coverage Before Final Installation: Temporarily install spray heads and run the system to check for uniform coverage and make adjustments as needed.
Adjust Arc and Radius Settings: Many spray nozzles allow adjustments to the arc and radius to tailor coverage to your specific landscape.
Maintain Clean Nozzles: Dirt and debris can clog spray heads, leading to uneven watering. Remove and clean nozzles regularly to maintain performance.
Account for Wind Conditions: In windy areas, use low-angle nozzles to minimize spray drift and ensure water reaches the intended target.
Upgrade to High-Efficiency Nozzles: Consider nozzles designed to reduce water runoff and increase efficiency, especially in areas with water restrictions.

By leveraging the Spray Head Performance Chart and adhering to best practices for irrigation system design and maintenance, you can achieve optimal water use and a thriving landscape. For more detailed calculations or specific system requirements, consult an irrigation professional.