A butterfly valve is a specialized valve used to control liquid or gas flow through pipes. The rotating disc in the valve is controlled by an exterior wheel, allowing it to be completely shut off when necessary.
There are several types of butterfly valves, each with a unique purpose. A high-performance butterfly valve is used to control the flow in systems with extremely high pressure. A pneumatic butterfly valve, on the other hand, is optimal for pressurized air systems that operate at a much lower pressure. For more complex systems, butterfly valves with multiple shut-off points are necessary. A triple offset butterfly valve provides a tighter seal because it is mounted in three positions.
Further versions of the butterfly valve use a different method of pipe connection. A flanged valve, for example, has raised edges in the enclosure so that the valve can be bolted in between two pipes. Another type of valve called a wafer butterfly valve is installed in between two flanges with nuts and bolts. A traditional valve has a manually operated control lever, but electronic controls are also possible and even desirable for automated systems. Read More…
Manufacturers generally use plastic, stainless steel, or cast iron when creating butterfly valves. Different materials and standards of performance are expected for different applications. A butterfly valve that is AWWA certified meets all of the safety and efficiency standards of the American Water Works Association.
Of the three materials used to create butterfly valves, plastic is the least common. While it is cost-effective, it can’t withstand harsh chemicals or high pressures. A plastic valve is simply a disc composed of thermoplastic materials molded into one piece. Stainless steel valves are used in applications where resistance to corrosion and oxidation is important for consistent performance.
Stainless steel is more durable than other metal (including untreated steel) and it can easily be cleaned in applications where sanitation is a concern. For the most heavy duty uses, cast iron is the material of choice. It’s strong and able to hold back high pressure for as long as necessary when the valve is shut.
When designing a butterfly valve, it is critical that manufacturers consider the properties of the liquid or gas that the valve will be expected to control after being installed. In some cases, the shaft might be designed as two pins rather than one solid rod. While the general design and function of a butterfly valve has remained largely unchanged with time, some of the fabrication processes have changed.
Manufacturers now understand more about how particular metals will react to fluctuations in temperature and high or low pressure. This knowledge helps to prevent costly system malfunctions and valve failures. Improved CNC machining equipment also makes it possible to cut the valve assemblies with such extreme precision that leaks are not possible and the pipe remains fully blocked off when the valve is shut.
Butterfly valves are important to processes and operations in many different industries due to their range in size and their ability to control the flow of liquids and gases. Not only can they stop or start flow, but a partially opened butterfly valve can limit or reduce flow as desired. Valves are always tested and carefully inspected before installation to ensure that no weak points are present.
While there are many different possible applications for butterfly valves, some specific uses include: food processing (liquid), waterworks, irrigation, pipe fabrication, industrial manufacturing, heating systems, and chemical transport.