Valves & Valve Boxes
|By Adam Whelan|
If you think of an irrigation system as somewhat similar to the human circulatory system, it may be a little easier to understand how it works. Although there are other components that make up an irrigation system, for purposes of this article we will address only valves and valve boxes, taking into consideration that the valves being installed are underground.
So, to continue our analogy, picture an irrigation system, like the circulatory system in the human body, precisely pumping fluids through lines to where their nutrients and life sustaining abilities are needed most. Here, the pipes are obviously akin to the arteries and veins. The controller is like the brain, and the valves are the heart. Without the heart, nothing gets where it needs to go, when it needs to get there, and in the desired quantity. The same is true for the valves in an irrigation system.
The valves/heart gets all the attention, but there’s another essential part that’s often taken for granted. If the valves are the heart of the operation, then let’s say their valve box is like the ribcage. The heart gets all the love songs written about it, but if it wasn’t for the ribcage, nobody would be able to get past the second chorus before a moderate bump to the chest triggered a massive coronary—and a dead country western star.
As with the human heart, we’ve developed techniques to improve/ repair the valves in an irrigation system; they’ve undergone a significant electronic evolution. Originally, they were completely mechanical, requiring manual opening and closing. Then, they were controlled by hydraulic tubes that pressurized the valve to open or close. After that came electromechanical, putting a solenoid on the valve and using electrical current to open and close the valves.
Now, valves have joined the rest of the world in the digital revolution of the 21st century. Properly set up systems use electronically-controlled sensors and timers. These timers and sensors efficiently, accurately, and dependably dispense water to the proper places at the proper times.
These valves use solenoids that work in tandem with an electronic or solid-state digital controller, to give the contractor complete control over the system. When the controller decides it’s time to water an area, it sends an electrical impulse to the solenoid of the appropriate valve, which then activates the valve. Water can then flow through the valve from the inlet to the outlet.
“It’s really a bit of a science and an art,” said Robert Hickey, sales manager of Highline Products, based in Lexington, Massachusetts. “It requires trained professionals to size everything for the area being covered, and to design it so that it runs with maximum efficiency.”
Part of that art is knowing what valves work best for different applications. Factors such as flow rate, materials, and valve type all go into what makes the perfect valve for a job.
According to Todd Polderman, product marketing manager of Hunter Industries, “It’s also worth keeping in mind that the city will deliver water to the main connection at a certain pressure. The farther you get from that, the more the pressure will degrade.” For this reason, it’s best to place the valve box closer to the city line.
For valves that will be installed in an underground valve box, a globe valve is typically used. This is because globe valves can handle more water flow and pressure. In some residential markets, above-ground anti-siphon valves are used.
“Different valve models each have their own flow rate,” says Shepersky. “A larger valve will have a higher flow rate, and the size of the valve is determined by how much flow you need.”
Anti-siphon valves are limited to ¾-inch and one-inch diameters, which makes their maximum water flow more limited. However, for residential properties, in areas where they meet the backflow prevention requirements, anti-siphon valves are probably more cost-efficient and appropriate.
Despite their high-tech status, just burying the valves on their own doesn’t do much good. According to Shepersky, “Originally, in some old systems, the valves were not in boxes, they were backfilled in the trenches along with the pipe. But when the valves couldn’t be found for servicing and maintenance, people realized they needed access. Popping open a valve box lid is a lot easier than having to dig.”
At the end of the day, a valve box is what keeps all of your equipment clean, organized, easy to find and, for the most part, dry. Considering that a valve box can commonly be picked up for less than $50, it will easily pay for itself in maintenance costs, serviceability, and peace of mind. Unless there is a an extenuating reason to keep a system’s valves above-ground, a valve box or boxes should be considered a mandatory component of modern landscape irrigation systems.
At one time, valve boxes were made of concrete. They were heavy and expensive. Today, valve boxes are made out of a polyplastic that’s relatively universal. Some models use a solid-injection method for the mold, while others use a less expensive foaming agent that is slightly less structurally sound. The biggest difference between models is usually size, though some are made to house valves that are themselves above ground.
You should know before you begin a project how many and what type of valves you want to put in a box. When you dig the hole for the box, make sure the hole is big enough for the box to easily fit into.
The hole should be about four inches deeper than the box, in order to make room for a crushed rock base underneath. Gravel can also be used, but rock is more stable. This base will allow for better drainage and act as a barrier against rodents, such as gophers digging into the box from underneath.
You do not want to cram too many valves into a box; then you end up with insufficient hand space to service them properly. After digging and preparing the rock base, lay out and connect the pipes on the spot. Note where the pipes will be exiting the box and cut it accordingly, so that it can be placed over the valves and sit on the rock base. From here, you will need to backfill the hole around the box with a hand shovel. Keep in mind that the soil can compact and it might become preferable to add more at a later date if the box’s lip rises above ground level.
When it comes to installing valves and their boxes, there are no shortcuts. “Shortcuts are typically the thing that will mess up a project,” said Hickey. For example, while it may be tempting to save work by cramming as many valves into a box as possible, it’s a shortcut that’s sure to come back and bite you. It may seem like efficiency—using only one box puts everything in the same place. It uses fewer materials, and can drastically cut down on installation time. But when it comes time to service the valves inside that box, those benefits are going to be paid back.
You may find that the valve placement you completed during the installation has made it impossible to find the hand space necessary to service a malfunctioning valve. Piping and valves can easily end up obstructing the removal of bolts and/or other valves, making it difficult to properly see what you are doing.
It is also recommended that all pipes and wires are labeled, as well as the box itself. If there are unlabeled criss-crossing pipes and wires, jammed full the box is of five valves and a main line, and dirt and water has seeped into the box, it can be a trial just to locate the part you’re trying to service. And that’s assuming everything was cramped, but organized.
For enough hand spacing in a standard 14- to 17-inch box, Shepersky recommends using “2- to 3¾inch or one-inch valves per valve box. If you’re using 1.5-inch up to 3- or 4-inch valves, they should have to be one per box.”
Also make sure to tighten the bolts on a box’s lid after installation or servicing. It may seem extraneous, as anyone can just take them going to mess with a valve box any- off, and you may be thinking who is way?
But an unbolted valve box is more than just an invitation for Little League coaches to shut off the sprinklers for extra practice time. You’re making theft and vandalism that much easier. More commonly, says Kevin Rost, vice president of Dura Plastic Products in Beaumont, California, “Many people leave out the bolts in the bolt holes, but that also leaves an entry point for small animals.” The holes will also let water and fresh air into the box, attracting more attention.
One of the pet peeves of contractors opening valve boxes to inspect or repair wires or valves located in it is what’s lurking inside when they open the top.
Such cool underground environments create breeding grounds for mice, gophers, snakes, spiders, bees, and various other insects. The holes provide a means of entry into a new home for small creatures that are magicians at compacting themselves. You don’t want to open a valve box only to be surprised by a real-life version of the snake-in-a-can-of-nuts prank. And the more dangerous animals—like rattlesnakes and Black Widow spiders —can do a lot more than scare you.
Because of these kinds of complaints, Dura Plastics has introduced the ‘Dry Box.” It’s designed to turn the box into a watertight environment for valves.
These boxes feature a bottom lid as well as a top. Both ends use gaskets to compression-seal the box and ensure that water, silt, insects, and other animals are kept out. They are a bit harder to install and require that the cutouts in the box’s side be circular, as the pipes have to be threaded through there.
The dry box has the ability to keep the valves inside the box dry without worrying about potential water damage. Also, the safety factor of not having to worry about Black Widows or snakes biting someone is a key factor. For these reasons, the dry box may be the way of the future.
If valves are the heart of the irrigation system, it behooves us to make sure they are in good working condition. By installing them in valve boxes and checking on them once in a while, they should give you many years of good service before you need to replace them.