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posted on 11 Dec 20
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Improve Irrigation System Performance with Proper Pump Maintenance and Testing

This article was originally posted on the USGA website

“The squeaky wheel gets the grease” is a proverb that is both literally and figuratively true for golf courses. But with ever-tightening budgets, sometimes it’s the mower with the bad bearings, not the one that’s just squeaking, that gets the grease. When money is tight, an irrigation pump that seems to be working fine is probably not going to get much attention. Unfortunately, there are serious problems that come with neglecting pumps until a catastrophic failure happens – with huge upfront costs and the risk of widespread turf damage being the two biggest potential concerns. The good news is that pump station failure is usually avoidable – or if not avoidable, at least failure can be forecasted.

Irrigation systems have lots of parts and the pumps may be the most neglected and most misunderstood components of them all. The pumps used in golf course irrigation stations, under normal conditions, can last for years if not decades. It is not unheard of for the pumps to outlast multiple superintendents. A common statement from superintendents is “That pump hasn’t been touched since I’ve been here,” which illustrates the room for improvement in pump maintenance.

Every pump motor should have a tag that lists the manufacturer, model number and other specifications that can be used to determine appropriate maintenance intervals. It’s also important to remember that catastrophic failures aren’t the only pump station issues that superintendents should be worried about. The pumps in the pump station were sized to meet the designed volume and pressure of water. As the pumps become less efficient over time, they do not move the same volume at the same pressure. At first, the drop in performance may not be noticeable at the sprinkler head. However, even a slight reduction in performance can result in increased electrical costs which could equate to thousands of dollars wasted over the course of a season.

Preventative Pump Maintenance

Preventative maintenance can prolong the life and efficiency of the pumps. Preventative maintenance on pumps in both the irrigation pump station and the water well can be very cost effective, even when paying a service company. The first step is to determine what the manufacturer suggests for maintenance. Pump system manufacturers will be able to provide you with a specific schedule for service that they recommend for a particular system. If you have a system with components that did not come from only one manufacturer, service information is still available to you but will require some additional legwork on your end.

All pump motors require some basic, periodic maintenance like greasing the bearings and adjusting shaft seals. The shaft seal on vertical turbine pumps is commonly called “packing.” These types of services are typically performed on an interval ranging from every three months to once a year depending on hours of use. For other common service intervals please refer to the table above.

The shaft seal on this vertical turbine pump is compromised and in need of new packing. Neglecting your pumps will lead to premature failure and costly repairs. 

Preventative maintenance also includes diagnostic testing. Performance tests that show the health of the pump and motor are extremely useful. A pump test completed by a service company will allow you to accurately assess your current pump condition.  The process involves isolating each pump from the rest of the system, so that the gallons per minute (GPM) data collected can be plotted on the manufacturer’s pump performance curve. The performance curve is a graph of the ratio between total dynamic head (TDH) and water volume (measured in GPM). The curve produced from the pump test can be compared to the original curve from when the pump was new. Once a drop in performance is quantified, timeframes for repairs and budgeting decisions for replacement can be forecasted. A performance test is also the best way to determine the energy cost implications of an inefficient pump.

Characteristic efficiency curves for a deep-well turbine pump. (source: Hydroflo Pumps USA, Inc.)

The importance of proper pump maintenance applies to water well pumps also. Some golf courses supply their own water pulled from underground sources. Testing the pumps that draw this supply is just as important as testing the ones that distribute water around the course. Pump tests performed on a water well can show the health of the pump and the water well productivity. Pump tests should be run on water wells every one to three years. If the pumps have not been tested recently and a service history is lacking, it may be best to run a pump test in two consecutive years to build a baseline for future comparison.

Pump testing should be completed not only for the irrigation pump station but at each individual water well. 

Another important test that a pump service company can provide is called a vibration test. A vibration test, unlike a pump test, does not measure flow rates but can indicate potential issues like bearing wear, shaft misalignment or unbalanced impellers. The two tests can be combined or performed independently to help assess the current condition of the pumps and motors. If you haven’t had them done recently, it is probably best to reach out to your local pump service provider and arrange for an evaluation.

Pump Types and Longevity

Pump stations and water wells use a variety of pumps. Centrifugal, vertical turbine, submersible, and horizontal split-case pumps are some of the more common types found on golf courses. At first glance, the variation and complexity of pumps can seem overwhelming. Yet, the basics of a pump are all the same. A pump consists of an impeller inside a bowl-shaped housing. The impeller is spun at high RPMs by a motor. Pumps can have more than one impeller and the more impellers a pump has the more water pressure it will build. Some pump maintenance can easily be completed in-house, but some work is best done by a professional pump technician.

An example of a pump that will last for decades if properly maintained is the vertical turbine. Vertical turbines are commonly used to pull water from a lake or a water well. The basic design is the pump sits submerged in the water and a shaft runs to a motor resting above the water. The advantage of this design is the motor is never submerged and can easily be serviced. Regularly greasing the motor bearings is a simple task that can keep that pump running for decades instead of years. Performance tests every three years will allow you to track the health of the pumps. As performance wanes a plan can be put in place to have the pump pulled and rebuilt in the offseason when irrigation demand is minimal.

Dirt, sediment and mineral buildup can degrade pump impellers. As such, every effort should be made to screen water before it enters the suction line.
Causes of Pump Failure

Once you have run pump tests and vibration tests, the results may show that the pump does not perform as well as it did when it was new, which is not unexpected. Pumps, just like any mechanical device, will wear out over time. When the metal fatigues or thins out, the tolerances needed to move water efficiently are lost. A pump test is usually the only way to diagnose this issue unless a major failure occurs. Given the fact that a major failure could result in turf loss, it is good to track performance over time so that issues can be anticipated and prevented.

Some water conditions like high total dissolved solids (TDS), extreme pH levels, or biofouling will prematurely wear and clog pumps. These conditions usually can be treated to help reduce the wear on pumps. However, just because some of these water characteristics are present does not necessarily mean the water will need to be treated. A pump test can be used to determine what degree these conditions are affecting the pump and how long it will last under the current conditions. Depending on the conditions, treatment might be a lower-cost option than complete pump replacement. Bearing wear, shaft alignment and trash on the inlet screen are also things that contribute to pump failures.

Summary

Preventative maintenance is an easy sale when compared to the alternative of unpredictable, premature pump failure. To get started, gather information about the make and models of the pumps in the irrigation pump station and water wells. Turn to the manufacturer for suggested service tasks and frequency. In general, pump motors will require small amounts of grease to be applied one to four times a year. Some motors require oil for lubrication but those that do often do not require frequent attention. Inspection of seals for leaks can be easily performed monthly. Running pump tests and a vibration test once a year can help catch issues before they become major problems. It is usually best to run the test at the end of the growing season. That way, if repairs are needed, they can be performed when water demand is low.

As pumps tests are acquired, the data should be evaluated over time to determine the rate at which pump performance is deteriorating. If the pump has a substantial drop-off in performance, then you may want to bring in outside help to determine the cause. Do not replace a pump without knowing the underlying cause of its failure. Otherwise the new replacement may fail just as quickly. When a pump is replaced or rebuilt, run a pump test on it immediately to know how it performs from day one. These simple steps can save money by making your pumps more energy efficient and helping the equipment last for its full life expectancy.

Derek Nees is a Registered Geologist and Project Manager for Brotcke Well & Pump, Inc.

This article was originally posted on the USGA website
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