The Large Terracotta Valve is an unpowered irrigation valve suitable for automatic sprinkler irrigation or drip irrigation. The valve operates in the pressure range 10 kPa to 800 kPa. The valve does not require an irrigation controller. Each valve is self-controlled whereby variations in the irrigation frequency are automatically controlled by the on-site prevailing weather conditions (namely, evaporation and rainfall).
Terracotta is porous and so the water level in the bowl falls as water evaporates from the outside surface of the bowl. A float inside the bowl floats on the water. When the water level reaches the low level, a magnet inside the float activates the valve so that the valve opens and the irrigation starts. During the irrigation event a control dripper drips water into the bowl and the water level rises. When the water level reaches the high level, the magnet inside the float disengages from the valve so that the valve closes and the irrigation stops.
During an irrigation event, the control dripper replaces the net volume of water that has evaporated since the previous irrigation event. This volume is called the control volume. The Small Terrcotta Valve has a control volume between 90 ml and 275 ml. The Large Terracotta Valve has control volume between 400 ml and 2300 ml.
Key features of the Large Terracotta Valve
- Completely automatic
- No electricity required (no batteries, no solar panels, no electronics, no computers, and no WiFi)
- Water in the terracotta bowl is protected from algae, mosquitoes and thirsty animals
- No timer required
- Smart irrigation – the irrigation is controlled by the prevailing weather conditions
- Valve operates in the pressure range 10 kPa to 800 kPa
- Use for both gravity feed and pressurised irrigation
- Use with PC (pressure compensating) drippers and NPC (non pressure compensating) drippers
- Use for sprinkler irrigation, drip irrigation, or porous hose irrigation
- Adjust the water usage by adjusting the control dripper
- Adjust the irrigation frequency by adjusting the float
- Adjusting the water usage does not affect the irrigation frequency, and adjusting the irrigation frequency does not affect the water usage
- The water usage and irrigation frequency are directly proportional to the net evaporation rate (evaporation minus rainfall)
- Responds appropriately when there is an unexpected heat wave
- When it rains, water enters the terracotta bowl and delays the start of the next irrigation
- Uses less water without affecting the yield
- Simple, unpowered, and low tech, and therefore fewer things can go wrong
- Provided you have a continuous water supply, you can leave your irrigation application unattended for months on end