3. Routine Maintenance of System Components

Routine maintenance involves “preventative” practices that all micro-irrigation systems should receive regardless of age. Proper attention to the following will decrease the likelihood of irrigation system failure:

3.1. Pumps

Follow manufacturer's recommendations to maintain submersed turbine or above-ground centrifugal pumps.

Turbine pumps require little maintenance. If failure does occur, repair requires the removal of the pump, which can be complicated and expensive.

  • During the irrigation season, check above-ground pumps at each site visit for:
  • Excessive or unusual noise or vibration.
  • Water leakage.
  • Proper flow rate and pressure.
  • Intake screen obstructions.

3.2. Power units

Electric motor routine maintenance:

Dirt and corrosion
  • Wipe, brush, vacuum, or blow accumulated dirt from the frame and air passages.
  • Feel for air discharge from the cooling air ports. If the flow is weak, internal
  • passages are probably clogged and require cleaning.
  • Check for signs of corrosion and repaint or repair if necessary.
  • Open the conduit box and check for deteriorating insulation or corroded terminals.
Lubrication
  • Lubricate bearings only when scheduled, if they are noisy, or if they are running hot. Do not over-lubricate.
Heat, noise, and vibration
  • Feel the motor frame and bearings for excessive heat or vibration. Listen for abnormal noise. Promptly identify and eliminate the source of these problems.
Winding insulation
  • If records indicate a tendency toward periodic winding failures, check the condition of the insulation with an insulation resistance test.
Diesel engines

During the irrigation season, visually check the engine at each site visit for:

  • Proper oil pressure and coolant temperature.
  • Fluid (oil, fuel, coolant) leaks or stains.
  • Excessive noise or vibration.

Regularly check the engine oil level with the system off.

Change the following based on the manufacturer's recommendation:

  • Engine oil.
  • Engine coolant.
  • Oil and fuel filters.
  • Tune up the engine and take other preventative measures once a year or as the manufacturer recommends.

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3.3. Water Filters

Proper water filter performance is critical to minimize emitter plugging. Filters must be periodically cleaned of accumulated particles and debris.Backwashing is a typical cleaning method. A partially clogged filter may reduce system pressure, resulting in reduced and nonuniform water application. Clogged filters also increase pump pressure head and consume extra energy.

Schedule filter backwashing either manually based on a time interval or automatically based on pressure differential.

  • If possible, use automatic backwashing. Set the automatic backwash to operate on a 5 to 6 psi pressure differential.
  • If backwashing manually, determine cleaning frequency based on the length of time it takes for particles to accumulate.

During irrigation periods, inspect screen and disk filters monthly (or more frequently if needed) by removing the cover and examining the filter element:

  • With screen filters, check for tears or extruded material in the screen.
  • With disk filters, check for accumulated organic material on the outside of the disks, and check for sand or other particles that may have become wedged between disks.

Check sand media filters at least twice a year:

  • Check for appropriate sand level.
  • Look for caked material in the media.
  • Make sure media has not flushed out during backwash.
  • Make sure cavities have not opened up.

Routinely inspect all components related to automatic backwashing:

  • Hydraulic tubing.
  • Pressure regulators.
  • Pressure gauges.
  • Control valves.

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3.4. Chemical injection equipment

Visually inspect injection equipment components each time a chemical is injected into the irrigation system:

  • Hoses.
  • Valves.
  • Pumps.
  • Injector.

Be sure to flush the injection system with water following each chemical injection so corrosive chemicals do not remain in the equipment.

3.5. Automatic valves

Automatic diaphragm valves are relatively reliable but require periodic inspection to assure proper operation. If a valve failure goes undetected, the pump or power unit could be damaged or water could be applied where it is not needed.

Inspect and clean diaphragm valves at least once a year. A valve can usually be cleaned without removing it from the line.

  • Clean deposits that have accumulated on the valve stem.
  • Remove encrustation with a wire brush, a weak acid (like vinegar), or very fine sand paper.

When a valve is opened, inspect the diaphragm, seat, and o-ring seals. Replace any components that are beginning to wear out.

Periodically inspect adjustable pressure regulating valves to ensure correct setting.

If regulating valves are pre-set, check them with a pressure gauge mounted at the regulator, or by attaching a portable pressure gauge to a Schrader valve.

3.6. Pressure gauges and flow meters

Check pressure gauges occasionally to make sure they are working.

  • Use high-quality liquid-filled gauges.
  • Make sure the range of pressure measured by the gauge covers the operating range of the system.
  • Check gauge accuracy by comparing with a new gauge or a standard test gauge.
  • Occasionally observe flow meters while the irrigation system is operating.
  • Make sure the flow rate observed is reasonable for the system.
  • Repair or replace a malfunctioning flow meter as soon as possible.

3.7. Field pipe, tubing, and emitters

Visually check irrigation system field components for leaks each time you visit a running system. Leaks can develop in plastic system parts (often resulting from animal chewing) and in hardware components like pipe fittings, emitters, and hose adapters.

Walk or ride the field, observing or listening for excessive water flow.

When micro-sprinkler stakes are knocked over, the sprinkler pattern becomes grossly distorted. Check for this problem by surveying emitters as they operate.

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