How It Works | Indexing Valves

Let’s break down how the indexing valve works step by step:

• Valve Setup: The indexing valve is a component in an irrigation system designed to water different zones (sections) of a garden or landscape one at a time. It’s placed along the main water supply line and connected to the various irrigation lines that lead to different areas.

• Chamber Arrangement: The indexing valve consists of multiple chambers (4, 6 and 8) that are arranged in a circular pattern within the valve housing. Each chamber corresponds to a specific watering zone.

• Stem and Disc Design: Inside the valve housing, there is a stem and a disc. The stem has wings or tabs that fit into corresponding notches on the disc. These tabs are designed to engage with a pre-set cam.

• Cam Configuration: The cam is a specially shaped component that’s set up according to the desired watering sequence. It has different lobes or indentations, each representing a specific zone. The cam is aligned with the stem and disc.

• Water Flow and Pressure: When water flows into the valve, it enters one of the chambers depending on the position of the stem and disc. The stem and disc are positioned by the previous cycle of the valve. As water enters the chamber, it flows out through the irrigation line connected to that specific zone.

• Depressurization and Indexing: When the water flow is stopped, the valve depressurizes. This allows a spring located at the bottom of the disc to expand. As the spring expands, it pushes against the disc, causing the stem’s wings to rotate and engage with the cam’s next indentation.

• Switching Zones: With the stem now locked into the new position on the cam, the disc also shifts, aligning the openings or ports on the lower half of the valve body with a different chamber. This prepares the valve for the next watering cycle.

• Resumption of Water Flow: When water flow is turned on again, the pressurized water pushes against the disc, causing it to rotate. This rotation directs the water to the new chamber that’s now aligned with the open ports.

• Zone Watering: Water flows out of the newly aligned chamber into the corresponding irrigation line, effectively watering the next zone in the sequence.

• Repeat Cycle: This process repeats each time the water flow is turned on and off. The valve goes through the indexing and switching steps, allowing water to flow through one zone at a time.

The indexing valve works by using a combination of pressure, spring action, and a pre-set cam to rotate the stem and disc. This rotation controls which chamber is connected to the water supply, allowing water to flow through different irrigation zones sequentially. The valve’s design ensures that each zone receives its turn for watering, and the cycle repeats whenever the water flow is controlled.

Imagine the indexing valve as a clever mechanism that controls the flow of water in a garden irrigation system. It’s like a traffic cop for water, allowing it to move through different sections of the system one at a time.

The valve has a special design with a stem and disc, and it works together with a cam that’s designed specifically based on how many different areas (zones) you want to water. The stem and disc can rotate around a central point inside the valve, and they have small openings or ports on their lower halves.

When the water flow stops, the valve releases its pressure, and this lets a spring at the bottom of the disc expand. This spring action makes the wings on the stem move and fit into the cam’s design. It’s like the valve’s way of saying, “Okay, I’m ready for the next zone now.”

As the water starts flowing again, it presses down on the disc, and this action guides the water to the next area that needs watering. It’s like turning a switch to direct the water to a new location.

However, this valve is a bit particular. You need to control the water source carefully, completely turning it on and off, so that the valve can do its job properly. Think of it as starting and stopping the flow of water to the valve in a very specific way, like flicking a light switch just right for it to work correctly.

So, in simpler terms, the indexing valve is like a water traffic controller that lets water flow through different garden zones one by one, and it uses a smart system with a rotating stem and disc to make sure the water goes where it’s needed.

Why are indexing valves inefficient ?

Here’s how indexing valves are less efficient in various aspects:

1. Lack of Zone-Specific Control:
   • Indexing Valves: Indexing valves water zones sequentially, one at a time. This means that all zones are not active simultaneously. As a result, if you have multiple zones with different watering needs, some may receive too much or too little water.
   • Electric Control Valves (e.g., Irritrol 205): Electric control valves allow for individual control of each zone. This means you can customize watering schedules, durations, and frequency for each zone, ensuring that each area receives the precise amount of water it needs.
2. Precise Timing and Scheduling:
   • Indexing Valves: Indexing valves often rely on the duration of water flow to determine how long each zone is watered. This may not offer the precision of electric control valves, which can be programmed to start and stop watering at specific times of the day or night.
   • Electric Control Valves: Electric control valves offer precise timing and scheduling options. You can set watering times to optimize water efficiency, prevent overwatering, and adapt to changing weather conditions.
3. Flexibility and Zone Isolation:
   • Indexing Valves: It can be challenging to isolate or shut off individual zones with indexing valves. If you need to make repairs or adjustments to one zone, you may have to turn off the entire system, affecting other zones.
   • Electric Control Valves: Electric control valves allow you to isolate and control individual zones independently. This flexibility is crucial for maintenance, repairs, and optimizing water distribution.
4. Response to Changing Conditions:
   • Indexing Valves: Indexing valves typically follow a fixed watering sequence. They may not respond to changing weather conditions, such as rain or moisture in the soil, which can lead to overwatering.
   • Electric Control Valves: Electric control valves can be integrated with weather sensors and moisture sensors to adjust watering schedules based on real-time data, improving water efficiency.
5. Ease of Use and Programming:
   • Indexing Valves: Setting up and programming indexing valves, especially for a large number of zones, can be complex for beginners. Calibration may be required for efficient watering.
   • Electric Control Valves: Electric control valves often come with user-friendly controllers that make programming and customization more accessible, even for those with limited experience.
6. Reduced Maintenance Needs:
   • Indexing Valves: Indexing valves have moving parts like the stem, disc, and cam, which may require more frequent maintenance and are susceptible to wear and tear.
   • Electric Control Valves: Electric control valves generally have fewer moving parts and are designed for durability, reducing maintenance requirements and downtime.

In summary, electric control valves like the Irritrol 205 offer superior efficiency and control compared to indexing valves. They provide precise zone-specific control, flexible scheduling, and the ability to adapt to changing conditions, making them a more efficient choice for complex irrigation systems or landscapes with varying watering needs.