Trickle System Layout
Typical trickle system layout showing the many compontents that make up the system.
The main components of a trickle irrigation system are identified in the figure (numbers in parentheses match numbers in the figure). A pump usually provides the pressure and flow rate.
Pressure gauges (4) are the main devices showing the system is working properly. A clogged filter or a major break in the system results in pressure drops. A flow meter (6) shows the flow past its location in the system, but an accumulating flow meter is more useful. An accumulating flow meter helps the operator keep records of the amount of water used. In some areas, water permits require record-keeping.
AlI trickle irrigation systems need a filter (5) to remove any small particles that would clog the small emitters. The water then flows to the main lines (7) and submains or headers (14) where the trickle laterals (tubing) (13) provide the final distribution of the water. Different types of lateral connection devices (10) and lateral closure devices (12) are available.
At each zone or section of the irrigation system, a control valve (8) turns the water on or off. Often, in a small system this valve is a manual gate valve. Later, an electric solenoid valve frequently replaces the manual valve. An electric time clock (controller) controls the electric solenoid valve. A trickle irrigation system operates at a low pressure of 10 to 15 psi so a pressure regulator (9) reduces the pressure at each zone. Pressure regulation is a more important design consideration where there are elevation changes in the system.
When fertilizers or other chemicals are added to the irrigation system, there will be a chemical injection unit (2) in the system. It will have a check valve or other backflow prevention device (1) installed between it and the water source.
Finally, a good system also includes pressure relief valves (11) and air vents at appropriate locations. The pressure relief valve opens to discharge water to prevent excessive pressures in the system. The air vents allow air to escape at high points where it would accumulate. They are also placed at the ends of mains to release air as the pipes fill with water. The air vent also allows air to enter the pipeline as water drains out when the system is turned off. They prevent vacuums that might cause a backflow.
These components are not found on all systems, but note where they are placed and what their functions are. A well-designed irrigation system with pressure gauges in the right places gives a grower peace of mind. A quick check of the pressure gauge indicates if everything is working properly.