Maintenance, Troubleshooting and Repair of Micro-Irrigation Systems
What the exam tests
This domain tests routine maintenance schedules, fault diagnosis from symptoms, and safe repair of drippers, laterals, filters and pumps.
Core rules and concepts
- Routine work includes flushing laterals, cleaning screens, backwashing media filters, checking pressure gauges, inspecting emitters and repairing leaks.
- Chlorination controls organic clogging; acid treatment dissolves carbonate and mineral deposits. Never mix chlorine and acid because toxic chlorine gas can be released.
- Diagnosis should move from the head to the field: check source, pump, filter, main valve, submain, lateral and emitter in that order.
- Low pressure at the head affects the whole system; low flow at the end of one lateral points to that lateral, a valve or clogging.
- Repair methods include replacing damaged lateral sections, cleaning or replacing emitters, reseating connectors and correcting pump suction leaks.
- Records of flushing, chemical treatment and repairs help identify repeating faults.
Worked example
A field has 2.0 bar at the head, 1.8 bar at the first lateral and 1.0 bar at the last lateral. The design requires at least 1.5 bar at the last emitter. The head pressure is adequate, so the pump is not the first suspect. The large drop along the submain or lateral suggests excessive friction, a partly closed valve, a crushed pipe or a long lateral with too many emitters. The correct next step is to check the submain valve and measure pressure at several points, not to replace emitters immediately.
Traps that cost marks
- Replacing emitters without flushing the line.
- Mixing acid and chlorine.
- Over-chlorinating and damaging crops or equipment.
- Assuming one blocked emitter means the whole system is clogged.
- Repairing a leak without checking whether pressure or water hammer caused it.