Verifying the correct functioning of the drip irrigation system is a fundamental step to ensure its proper operation over time.
In order to diagnose any problems with the drip irrigation system, it is necessary to take some basic readings of the pressure gauges and flow meters, as a considerable part of the irrigation system is often buried underground. These are taken after verifying the proper functioning of the system components and allow specific problems to be identified and resolved promptly.
To take basic readings of the entire system, it is necessary to record the values of all pressure gauges and flow meters upstream downstream of pumps, pipe control valves on the surface, inlet and outlet from drip tapes or drip lines.
The main parameters to analyse are:
1. Flow rate of the drip irrigation system: knowing the flow rate of the system allows us to make decisions regarding the correct zoning of the irrigation system. The range of values in which the drip irrigation system flow rate must be included is between 30 l/min and 200 l/min depending on the characteristics of the system and the water requirements of the irrigated area. Moreover, knowing the flow rate allows, considering the diameter of the pipes, to calculate the speed of the water in the system (expressed in m/sec): the higher the speed of the water inside the pipe system, the higher the pressure drops that can compromise the correct functioning of the system. In this regard, it is advisable to maintain a water speed below 3.5 m/sec;
2. Pump pressure: ensures the movement of water within the system. The most used pumps in drip irrigation systems have a pressure between 3 and 6 bar;
3. Filter inlet pressure: provides an important indication of the force with which the water to be filtered is pushed into the filtration system. Verifying that the inlet pressure to the filter conforms to the specifications provided by the system designer allows us to verify the correct operation of the filtration system;
4. Filter outlet pressure: allows you to check the pressure losses suffered by the water when crossing the filter. When the difference between filter inlet pressure and outlet pressure is too marked, it is necessary to arrange appropriate backwashing operations in order not to affect the operation of the system;
5. Main control valve outlet pressure: provides an average indication of the systemic water pressure values of the entire system.
An advice to overcome these problems is to follow the specifications given by the system designer in order to avoid pressure drops.
An important indication of the correct basic functioning of the system is given by the appearance of the purging water coming out of the filter. If the water is clean and has no sand or soil residue it means that both the filtration system and the backwash valve are working properly.
Once the above basic readings have been taken, it will be necessary to check the operation of all other components by measuring the pressure at the inlet and outlet of the valves, the hose and the appearance of the purging water from the lines. In conclusion, the stabilization time of the system to reach the correct pressure and flow rate will be determined.