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An irrigation valve regulates the one-directional flow of water in an irrigation system. These valves are often found in sprinkler systems used for parks, golf courses and home lawns. They help control water flow in above-ground systems as well as in-ground systems that have been buried well beneath the surface to present a less cluttered, more attractive landscape.
There are two main types of irrigation valves. The most common type of irrigation valve, at least among commercial sprinkler systems, is the globe valve, also known as the angle valve. It gets its name because of its sphere- or globe-shaped body. More recent makes of globe valves no longer have a sphere shape. What makes a globe valve different than other types of valves is its internal use of a circular plug design that moderates the flow of water.
The anti-siphon valve is another type of valve which tends to be more commonly used in residential applications. This type of irrigation valve has two chambers in contrast to the single chamber design of the more popular globe valve. Siphon valves also have a built-in backflow preventer, unlike globe valves.
Traditionally, irrigation valves were made out of metals only. More recently, plastics are being used as a cheaper alternative. Plastic irrigation valves are typically durable enough for home and even industrial use. Manufacturers also sell more high-end valves molded out of material such as brass that can better withstand sudden water surges as well as pressure changes caused by clogs.
Irrigation valves serve an important role in irrigation systems. In-ground watering systems often have multiple irrigation valves to allow water to travel to different areas of a large section of land. The water is permitted to reach different zones at various times, meaning the sprinkler heads don’t operate at once. This is especially useful since many systems don’t have enough water pressure to activate all the sprinkler heads simultaneously. Each sprinkler head is regulated by a counter clock that’s wired to the irrigation valve, ensuring that water is sprayed at the appropriate interval.
Most irrigation systems are connected to their water source by a master valve. The master valve, sometimes called the emergency shut-off valve, connects the water source via circuit to the irrigation controller. The irrigation controller, or control valve, in turn, allows water to travel to different zone valves, which in turn distribute water to the sprinklers.
The origins of irrigation predate recorded history and probably began when humans first began to cultivate crops. The earliest forms include canal irrigation and terrace irrigation. Canal irrigation uses man-made waterways dug into fields, with smaller ditches diverting water to lines of crops. Terrace irrigation involves levels of different heights dug into the landscape itself, allowing water to flow downhill onto a descending row of cultivated planes.