As previously highlighted almost 50 percent of center pivot irrigation systems in New Zealand are now over 10 years old. This means they are beyond half their serviceable life and issues are starting to occur.

Water Strategies continues to undertake much infrastructure assessment work for clients, providing each with a detailed report on the remaining serviceable life alongside an associated 5-year capital expenditure plan. The following are the key points we’ve noted around sprinklers and pump sheds:

Sprinklers: Unfortunately, it’s unusual to find a center pivot irrigation system over 10 years old that has all its sprinklers of the right type and in the right place. Given this, we strongly recommend every irrigation system is checked annually with the sprinkler chart in hand. It doesn’t take long to do this as sprinklers are colour coded, and if you don’t have the sprinkler chart, then ask your design company for it.

In systems over 10 years old our testing also always finds sprinklers not working – rotating too slowly, blocked or excessively leaking water. The lifespan of a sprinkler is typically 10 years, but it is highly recommended they are tested at least every 5. Our testing shows for most surface water users the lifespan is 5 years, but for sediment free groundwater it can be well over 10. Sprinklers are one of the most important parts of an irrigation system, so it’s important they are working correctly.

Regulators: Regulators are an integral part of a pivot sprinkler system, particularly in undulating paddocks, as they ensure the right pressure is delivered to each sprinkler. They have a similar lifespan to sprinklers and are regarded as faulty once their outlet pressure varies by more than 10% from their rating. Water Strategies has developed a test procedure for regulators so we can provide our clients with a good understanding of their condition and remaining life.

A new sprinkler and regulator pack costs around $6,000 and as a rule of thumb this should be scheduled into the maintenance plan at least every 10 years.

Pump Shed: The three common faults we find with pumping systems are: misalignment; cavitation; and motor overload.

Misalignment is usually the result of a faulty install or poor repair job, but over time the bolts that fix the pump can loosen so need to be checked at least annually.

Cavitation occurs from poor design or installation on the suction side and can dramatically decrease pump life and increase energy costs. Pipework that is undersized or too long in length and suction lifts that are too high are the common causes.

Motor overload is also the result of poor design and can be recognised through excessive current draw and motor overheating. It can significantly decrease motor life and increase energy costs. Wrongly specified motors (undersized) are the cause.

Water Strategies assessment work demonstrates that it makes much sense to have your pumping equipment assessed by a specialist at least every 5 years, alongside ensuring a visual and noise inspection is carried out annually.

There’s much to consider when assessing the condition of your irrigation system, so if you’ve any questions the specialist team at Water Strategies is available to help.


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