Valves are incredibly useful devices that can be assembled with a variety of materials in order for them to work in separate ways. When gases and liquids are fed through passageways within different kinds of pipes and machinery, valves are used to control and regulate the flow of these fluids. There are different types of valves that have individual uses.
Check valves are designed to allow fluids to flow in only one direction. They are quite literally used to ‘check’ the flow of fluids in some cases, as if backflow occurs, the valve will close. The most common types of check valve are ball-check valves, diaphragm-check valves and stop-check valves.
Ball-check valves contain a spherical ball that sits above the opening, and prevents the fluid from flowing in the wrong direction.
Diaphragm-check valves typically make use of either a rubber diaphragm or a disc that rotates. Their job is to seal the opening of the valve if the fluids happen to flow in the wrong direction. To allow flow to pass through, the pressure must be greater on the upstream side.
Stop-check valves, unlike ball-check and diaphragm-check valves, are usually operative. The user has the ability to stop all flow, and this kind of check-valve will not allow backflow when the opening of the valve is open.
Ball valves contain a hollow spherical ball that rotates when the handle that it is connected to is moved (the valve can be operated manually). It is easy to determine whether the valve is in an open or closed position (the handle moves along with the ball). When the hole in the ball is in line with the flow of fluid, the valve is open, and the flow is able to pass through. When the hole in the ball is perpendicular to the flow, then the valve is closed. This type of valve is described as a quarter-turn valve, as when it is being operated manually, the handle is turned ninety degrees. It also provides an extremely secure seal when closed.
Similarly to ball valves, butterfly valves are a type of quarter-turn valve. They work in a similar way to ball valves, but they contain a disc that is connected to a handle, rather than a ball. This disc is always present when the fluids are flowing, unlike the ball in ball valves, so one drawback of using this type of valve would be that there is a pressure drop. However, they are favoured in some ways, as they are cheaper and lighter than other valves, making them more efficient.