Irrigation contractors must grasp the concepts behind the proper installation and maintenance of irrigation valves. Those who possess a deep understanding of these tenets are more capable of delivering reliable, efficient and sustainable irrigation systems, ultimately boosting client satisfaction and solidifying their professional reputations in their respective markets.
Simply put, valves in an irrigation system are like the beefy doormen outside a posh nightclub. They’re gatekeepers who open and close the velvet ropes, controlling water flow and pressure within the irrigation system and ensuring the heads at the end of the line receive the right amount of water at the appropriate time to function correctly.
Too little pressure and sprays will miss their marks. Too much pressure can have damaging consequences. Both scenarios result in inefficient and wasteful water use.
According to the pros, valves are an irrigation system’s most straightforward yet most complex components. As a result, their function and role within a system are often misunderstood by irrigation contractors.
Daniel Martinez, technical service and training manager at Fresno, California-based Rivulis North America, owned by Temasek and Jain Irrigation Systems, says it’s not uncommon for contractors to overlook valves when troubleshooting issues or responding to an alert.
For example, he was once called to a site for an irrigation system service call to address a mainline break. The system’s smart controller had been issuing numerous flow issue alerts, but they were repeatedly ignored because it was believed the controller was broken and the messages were being sent in error. After some sleuthing, it turned out that a previous irrigation contractor who was no longer servicing the system had switched out the existing rotors and spray heads for water-saving retrofits. However, the contractor didn’t adjust or switch out the valves to compensate for the reduced flow.
“There wasn’t enough flow [for the valves] to stay open … they just pulsed on and off, on and off,” Martinez says. “When the sprinklers were on, they looked like they were working, but if you looked closely, you could see they were pulsating and not working properly. If [the previous contractor] had just downsized the valve and the master valve, then the whole issue could have been resolved.
“They thought the controller was at fault, but it was just doing its job … alerting that there was a flow issue [in the system] that needed to be addressed,” he adds. “But it was the valve that had broken the main line.”
Size matters
Proper valve sourcing and placement significantly impact water flow and pressure distribution. Failing to understand the hydraulic principles behind their roles in an irrigation system leads to inefficient energy expenditures and excessive and wasteful water distribution.
For example, what are the criteria for choosing a 3/4-inch valve versus a 3-inch valve in the system? Craig Borland, CIC, CID, CIT, CLIA, CLWM, a frequent Irrigation Association educator, and Toro Irrigation sales team member, says the decision is based on the number of heads and the gallons per minute required for that specific zone.
“For example, I have a requirement of 80 gallons per minute on a particular zone,” he says. “I’m not going to use a 1-inch valve because that’s too small, and I’m going to lose a lot of pressure and risk creating a water hammer. That’ll make the valve slam shut and make a bunch of noise in the pipes and place [unnecessary] stress on the valve’s rubber parts and fittings.”
Instead, a larger version — maybe a 2-inch valve — will meet the minimum requirements with the least amount of pressure loss and alleviate the need for an additional pump to compensate for that loss, Borland says.
But a valve can also be too large for the flow. It’s recommended to follow the manufacturer guidelines and stay within outlined performance ranges, says Kurt Thompson, CIC, CGIA, CID, CIT, CLIA, CLWM, managing partner at IrriTech Training.
A general rule of thumb is that all valves need about two to three pounds of pressure loss to close promptly, Thompson says. Valves that don’t close correctly create critical problems in the system.
“If I get a valve and it’s too large, it may take a really long time for that force to build on top of the bonnet (the upper part of the valve body that protects the internal components and ensures water pressure containment within the valve), and before it can fill enough to start closing, the next valve in the sequence turns on and steals some flow out of the mainline,” he says. “So, instead of just one valve in the main line being open, now there’s two,” he adds. “And maybe the hydraulics in that system are such that the first valve will never shut as long as the second valve is open. When the third [valve] in the sequence opens, the first two haven’t shut yet either, and now you have three valves open. Now, nothing is running other than water out all over the place.”
So, valves must close promptly for the system to function correctly, Thompson says. He cautions, though, that if the valve closes too fast, it causes a water hammer, or a sudden intense shockwave that creates a loud banging noise and could compromise the system.
To mitigate this, Thompson advises contractors to always use valves with a flow control option to fine-tune the flow.
“All valves with flow control must be set properly upon installation and adjusted after spring startup,” he says. “With the water off, turn the flow control all the way off, till it stops turning. Then, open it two full revolutions, turn the water on, and watch the sprinklers perform. If they’re underperforming, open the valve slowly until you see them reach as far as they’re supposed to throw. When you see that, close [the valve] a quarter turn. Now, you have a properly tuned valve.”
If there are questions about correct valve sizing, the pros recommend contractors discuss the matter with their vendors, who can best advise them on the proper valve choice for the irrigation system in question.
Installation troubleshooting
Contractors will run into many common issues when installing, servicing or maintaining valves. One of the most common mishaps happens during installation. A properly functioning valve flows one way, and it’s not uncommon for a contractor to install it incorrectly. “There’s an arrow on [the valve], so make sure you find that arrow and make sure it’s pointed in the right direction with the flow,” says Paul Todd, CIC, CID, CLIA, general manager at Milwaukee Lawn Sprinkler Corp.
Another installation issue centers on correct valve wiring and the importance of being thorough in mitigating future electrical issues and shorts. The experts recommend using proper underground wire splicing techniques. This starts with avoiding generic wire nuts, which will rust and corrode when exposed to moisture, leading to weak connections and eventual failure. Grease-filled wire nuts contain a special sealant or grease that fills the gap between the wires and the connector. This sealant prevents water infiltration, prohibits corrosion and keeps the connections from loosening.
“With two-wire systems on a conventional 24-volt system, if there are any sort of splits or water gets into those places, [the valve] is prone to fail,” Todd says. “This can take years to show up, but they will show up.”
In a two-wire system that handles milliamps of current, Todd advises contractors to bend the wires together before securing them into the nuts. “It’s vital to make good connections,” he says. “I teach all my guys to spin all the wires together. This ensures good cooper-to-copper contact before the wires go into the nut.”
“It’s vital to make good connections. I teach all my guys to spin all the wires together. This ensures good cooper-to-copper contact before the wires go into the nut.”
– Paul Todd, Milwaukee Lawn Sprinkler Corp.
Lastly, ensure all debris has been flushed and cleared out of the mainline before the system is engaged. Failure to do so leaves a valve’s internal diaphragm and seat, which work together to control water flow precisely, vulnerable to sticking and not closing correctly or even not closing at all.
Contractors are also encouraged to make maintenance points accessible via an appropriately sized valve box for future maintenance and repairs.
To conveniently service valves, Thompson recommends installing them in no smaller than 10-inch round valve boxes. In addition, never overload valves into standard rectangular 14 x 19-inch valve boxes, he says. “So, for a 1-inch valve, you place no more than three or four valves in a standard rectangular valve box. Otherwise, you’ll never get your hands in to service them.”
Critical Partnerships
Meet your equipment vendor, your best friend, when troubleshooting installation and maintenance issues. They possess deep product knowledge and troubleshooting know-how and have access to technical resources that are an invaluable extension of the professional irrigation contractor’s expertise. Consider these factors, echoed by our irrigation experts, the next time you’re stymied attempting to diagnose and resolve installation and maintenance issues with pumps and valves.
Rich in knowledge. Vendors have an intimate understanding of the pumps and valve models they sell, including their design, functionalities, troubleshooting procedures and common failure points. Often, this knowledge is a rich resource because it goes beyond the basic understanding held by most irrigation contractors.
Technical know-how. In a pinch, the best vendors can tap into the manufacturer’s support network to troubleshoot an irrigation contractor’s problem that exceeds their knowledge and experience. This may be in the form of detailed service manuals or even a direct line to a product engineer.
Insider information. Good vendors have their ears to the ground and are current on industry trends, new industry tech and emerging issues with existing pump and valve models. They can share valuable insights that allow irrigation contractors to mitigate potential system issues before they become problems.
