Whether you are maintaining a sprinkler system in your backyard, running an irrigation system for agricultural crops, or keeping a greenhouse green, there are many different issues that must be managed to keep everything healthy and thriving.
One of those issues is knowing how to choose the right parts for the system itself. Specifically, what kinds of valves are ideal for your system?
Well, never fear, this is the topic that we will be grappling with today!
In the world of valves, there are many different sizes, shapes, and colors. Two general types of valves that are commonly used in irrigation systems are shut off valves and control valves.
SHUT OFF VALVES
Shut off valves come in plenty of shapes and sizes, but they do what their name implies by completely shutting off the flow of liquid.
The most common type is a ball valve. Ball valves rely on the turning of a lever handle to engage the on/off mechanism, a solid metal ball with a pipe-sized opening drilled through the middle.
When the opening aligns with the pipe, liquid is free to flow. When the opening is perpendicular with the pipe, flow is shut off. Opening the valve partially is not recommended as it can create cavitation and vibration, causing wear on the valve.
A second type of shutoff valve is the gate valve. Although sometimes used as a regulating valve, gate valves often use a hand wheel to make the shut off easier.
By using a hand wheel on a spiraling track, you gain a mechanical advantage that the lever of a ball valve doesn't offer. Turning the wheel drives the valve’s stem up or down, bringing the “gate” with it.
Control valves are sometimes referred to as “regulating valves”. They allow the user to determine the direction and the amount of flow that is released.
Control valves also come in a variety of designs. Some of the most commonly used manual control valves include globe valves and needle valves. Although the specifics of the designs differ, these two types of valves share a zig-zag or “S” shaped channel in the valve.
A stem, usually coming down vertically, introduces a stopper into the channel to completely close off the valve. When that stopper (or “needle” in the case of a needle valve) is raised, it allows liquid to flow freely through the opening and around the stopper itself.
CHECK VALVES vs. BACKFLOW
One common issue for irrigation systems is contaminated liquid flowing back up into the piping system. This is referred to as backflow. Check valves are great for backflow prevention.
They are a simple and dependable way to keep materials flowing in one direction so that the water source is not tainted. Check valves, also known as a non-return valves, arrest backflow by placing a barrier to normal flow that can only be opened by pressure in one direction.
It is recommended that the shut-off valve be placed at the point closest to where the water supply is. That way, if you need to work on the other irrigation control valves you can simply utilize the shut-off valve to stop the flow.
When purchasing valves for your irrigation system, it is important that you select a valve that is the same size and connection type as the pipe that you will be connecting to. For more information about determining the thread size check out this previous article.
If you do have a valve that is not the correct measurement, then you can use reducers, fittings, and nipples to allow the valve to fit the pipe.