The First Steps in Creating an Optimally Designed Irrigation System
Author: Richard Beale, Managing Director of J. Gey van Pittius
Creating an optimally designed irrigation system starts with understanding your water supply’s flow rate and pressure. If your system connects to a mains water supply or any other source with unknown flow vs. pressure, you must conduct a flow vs. delivery test. Ultimately, this crucial step determines how many sprinklers can run optimally on one irrigation zone, ensuring effective operation.
The flow vs. delivery test is a straightforward process but essential to avoid over-designing or under-designing your system. The test involves using a device designed to measure the water flow from your source. This can be done with a flow meter or by using a hose that empties into a container of known volume. By timing how long it takes to fill the container, you can calculate the flow rate at various pressures by throttling the valve, which is critical for designing the irrigation system.
At our company, we provide a unit for clients to borrow and conduct this test. We only ask for a refundable deposit for the equipment. Consequently, completing this test is vital. Without it, you risk designing an inefficient system. An improperly designed system can lead to unnecessary costs. This includes having more zones than required, running the system at too high a pressure, or experiencing poor sprinkler performance due to insufficient pressure.
Understanding the Test Results
After conducting the flow test, your results will resemble the following:
- Static pressure: 6.5 bar
- Container size: 20 liters
| PRESSURE | TIME | FLOW RATE (L/MIN) |
| 0 bar | 10 sec | 120 |
| 1.5 bar | 17 sec | 70.5 |
| 2 bar | 20 sec | 60 |
| 2.5 bar | 25 sec | 48 |
| 3 bar | 32 sec | 37.5 |
| 3.5 bar | 41 sec | 29 |
| 4 bar | 52 sec | 23 |
Overall, these results give you a clear understanding of available pressure and flow. Importantly, sprinklers need an optimum pressure for ideal performance. Excessive pressure can cause misting, which wastes water and reduces coverage. Moreover, misting evaporates quickly, especially in windy conditions, preventing water from reaching the ground. Conversely, too little pressure can lead to poor water distribution. Some areas may receive more water than others, resulting in wet and dry patches.
Installation Considerations
Carry out this test as close to the water meter as possible. Many plumbers install pipes that are too thin, causing excessive friction. Consequently, this reduces the water flow to your sprinklers. As a result, fewer sprinklers can operate simultaneously, which increases system costs and reduces efficiency.
To address these problems, consider installing a separate mainline from your water meter to the irrigation zone manifold. This installation can significantly enhance system performance. A larger pipe reduces friction, allowing more sprinklers to operate at one time. As a result, you will need fewer valves, have a less expensive controller, and enjoy faster irrigation cycles. Ultimately, a more efficient setup lets you water your garden more quickly, saving both water and money.
Choosing the Right Contractor
When hiring a contractor for your irrigation system, it is vital to ensure they start with the flow vs. delivery test. If your contractor skips this crucial first step, they may lack the qualifications or experience needed for a well-designed system. Ultimately, a thorough understanding of your water supply’s capacity is vital for an effective system. Any contractor who does not prioritize this test is likely to leave you with an inefficient and costly system.
At our company, we emphasize completing this test before moving forward with design and installation. Thus, this approach allows us to create systems that perform to the highest standards while being cost-effective.
In summary, the first step in creating a well-designed irrigation system is completing the flow vs. delivery test. This ensures your system operates efficiently, saves water, and avoids unnecessary costs. If you overlook this step, you increase the risks of poor performance, wasted water, and higher expenses. Therefore, always make sure to perform this essential test and design your system based on its result