Valves are useful pieces of equipment that help control, limit, and shut off flow in a system. In a garden irrigation system, you could use valves to control when different plants get watered. While it is universally agreed that valves are helpful, choosing the right valve can be frustrating. We hear many customers make statements like these: “So many types exist! Some of them do similar things! I don’t know what types of valves to use!”
In this article, we will outline what makes each unique valve. For basic users, the most important thing to remember is that a valve does one of two things: shut off or regulate. Some valves can do either/both, but this is a simple way to think of what you need a valve to do. It could help you in picking the right valve. We will now cover each of the major valve categories.
Ball valves are a good example of a shut off valve. They use a spherical seating to stop or allow flow. The ball has a hole through the center, so fluid can pass through when the handle is turned to the “on” position. When the handle is turned 90 degrees to the “off” position, fluid hits the solid side of the ball and is stopped.
Butterfly valves can function as a shut off valve or as a regulatory valve. They can fully shut off flow or be kept partially open, which limits flow. Controlling flow can be extremely helpful if you want to decrease pressure in a system. Fluid passing through a small opening will be restricted, making pressure further down the pipeline lower, depending on how far open the valve is. Butterfly valves can also be used as typical 90-degree turn valves, just switching between “on” and “off” positions.
Gate valves, while usually used as shut off valves, can also function as regulatory valves. They use a “gate” that drops or lifts to control flow. When the valve is open, the gate is stored in the tall upper section of the valve, which is where gate valves get their unique shape. Unlike the previous two valves, gate valves are not a quarter-turn valve. They use a hand wheel to open/close whereas ball and butterfly valves use a lever handle. This makes it easy to keep them partially open and also makes operation of any kind easier.
Check valves come in many forms. The primary function of check valves is to prevent backflow. This makes them regulatory valves, as they control flow direction. Check valves are controlled by the fluid in the pipeline instead an operator, which makes them different from the valves we have previously examined. Check valves come in many different forms, but we will just cover the two most common types.
Swing check valves are a type of valve that uses a swinging function to prevent backflow in a system. The clear PVC swing check valve to the right has a disc that swings open if fluid is passing through the desired direction. If anything tries to flow backwards, the disc is pushed closed, stopping flow. Swing check valves create minimal pressure drop, as the disc is pushed completely out of the way when in operation.
The other major type of check valve is the ball check valve. Ball check valves use a ball or half-ball seating to eliminate backflow. When fluid passes the desired direction, it hits the rounded side and passes around and through. If fluid tries to flow backwards, it hits the concave side of the half-ball, pushing the valve shut. Due to the fact that fluid must flow around and behind the ball to get through, ball check valves produce moderate pressure drop.
Diaphragm valves, while not one of the most common types of valves, are very interesting and serve a specific purpose. They are perfect for limiting pressure in a system, making them regulatory valves. These valves have a flexible diaphragm that lowers toward or rises from a “weir” or “saddle” seating. The effect is that only a limited amount of fluid is allowed to pass through.
Choosing the Right Valve
In the end, picking the right valve depends on what you need it to do. No two jobs are the same, so there is no one-size-fits-all valve solution. However, you should now have all the information you need to make an informed decision.
NICO VALVES CORP. is a leading industrial valve manufacturer in Taiwan and China. The company offers various valves such as check valve, ball valve, threaded end valve, wafer check valve etc. If you have any questions, try to check out NICO’s website and feel free to send inquiry to them.