Essential pieces for irrigation flow

Features - Irrigation

Pumps and valves may seem like two smaller pieces of one large irrigation system, but their functions are key to the performance of the system.

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March 8, 2018
Lauren Rathmell
Photo courtesy of Munro

The nuts and bolts of any system keep things running smoothly and efficiently, and while they may be two small parts of one huge system, pumps and valves can make or break an irrigation system. There are endless options with pumps and valves, and it’s often hard to identify problems right away when the parts aren’t in plain sight.

Valve functions.

Ron Wolfarth, product manager for Rain Bird, says valves are the main thing that every contractor wants working without fail in an irrigation system. They act as the on/off switch for water and they can be challenging to replace.

“Ideally, you’d want a (contractor) to install the valve and never have to look at it again,” Wolfarth says.

Valves communicate with the controller, which sends a signal along, alerting the valve to operate and telling it how long to stay on. “It’s a relatively simple concept,” Wolfarth says. “But you want it to do its job the first time, for a long time.”

Valve selection.

There are many valve choices on the market, all designed for different applications. When selecting a valve, Wolfarth says installers need to consider the size of the site and what kind of flow is expected.

“You may need valves offered in different sizes for one zone,” he says. “So picking a brand that offers multiple sizes of the same type of valve might be important.”

Globe valves are a more common type of valve. These valves have the inlet on one side, and the outlet directly on the other side. Wolfarth says angle valves are more popular in regions that experience deep freezes. These valves have inlets on the bottom and outlets on the side because systems in colder regions are buried deep beneath the ground. There are valves that even allow the installer to move the inlet and outlet to suit their needs.

For average-sized residential systems, Wolfarth says installers can use smaller valves. These are less costly and the water pressure isn’t as high – usually a pressure rating to 150 psi will do the trick. In larger commercial systems, there are often long runs of main line so a higher-pressure valve around 200 psi is needed.

Valve repairs.

To avoid labor-intensive repairs, installers should be mindful of debris when installing a valve. Wolfarth says one of the most common reasons for a valve malfunction is debris getting stuck. “During installation or after a repair had been made upstream, debris gets stuck in the valve,” he says. “Especially if the system is operating at a low flow rate.”

Lower flow rates mean the valve doesn’t have to open very wide, making it easier for debris to get stuck. When debris is stuck in the valve, it may be lodged between the diaphragm. “When the diaphragm can’t seal closed, you’re going to get a leak or too much water,” he says. Malfunctioning valves can lead to an increase in water costs and property damage.

Since the valves may not be in plain sight, pools of water at the lowest point in the system might indicate something is wrong. For repairs, it may be as simple as turning the bleed screw to fully open the valve. “The next level would be to turn off the water, completely dismantle the valve and reassemble it,” Wolfarth says. “But, the diaphragm is made up of a soft rubber material and can be relatively easy to fix.”

Pump functions.

In an irrigation system, the pumps are designed to deliver a certain amount pressure to the system. Like valves, pumps come in various sizes to fit specific needs. “Basically, it comes down to pressure and flow,” says James Nelson, pump product manager for Rain Bird in Florida. “You need to figure out how much pressure you need from your critical zones, then work backwards from there.”

The function of a pump can differ depending on the type of system being installed. In boost systems, the pump provides pressure to flow the water because there is already enough volume. In a lift situation, the pump needs to provide volume and pressure. “If you have a water source that is shallow, like a cistern or well, you need the pump to lift that water out,” he says.

Pump selection.

Deciding what pump to use is a challenge. Nelson says pressure and flow are the basic factors to take into consideration and from there the installer will need to determine size. “Talking with someone who is really an expert is the best thing you can do,” he says. Nelson recommends consulting an irrigation system designer for selection. “It often comes down to budget and irrigation system design,” Nelson says.

Pump selection is also influenced by region and water source. For a source with a deep water table, submersible pumps can be useful because they can sit under the surface of the water.

Justin McDaniel, senior project manager with Munro Systems Integration, says pump selection includes what type of start the installer or customer wants. Pumps can be set up to start with a clock or when a certain pressure level is reached along with the ability to be controlled remotely. “The No. 1 thing to consider is being cautious of what the pump can lift. The pump needs to be able to lift the water,” McDaniel says.

Also, Nelson says there is demand for remote control access in irrigation systems such as the ability to monitor pumps remotely. “(Installers) want that option to be able to see how the pump is performing at any given time,” he says. “So we’re seeing a preference for (compatible) pumps.

pump repairs.

There aren’t many moving parts on an irrigation pump, so repairs can be simple. “A lot of pump failures are purely related to the motor,” Nelson says. “The motor will usually go before the pump station itself.”

Malfunctions can be prevented if the installer is diligent when performing that first installation. Problems with pumps can often be the result of a neglected intake line. “If the intake line is built incorrectly, that’s where we see most of the problems,” he says. “The problems usually lie on the suction end of the pump.”

Because some pumps – like the submersible kind – aren’t always in view, Nelson says to take some time and just listen to the pump to make sure it sounds like it’s running.

An installer will notice problems downstream from the pump station first, he says. Regular monthly inspections will help identify issues sooner and prevent serious property damage. “Sometimes it’s not until the grass is browning that people realize there is an issue,” Nelson says. “They’ll go check the pump and realize it hasn’t even been running.”