What is a butterfly valve and what are its uses?

A butterfly valve is a type of flow control and water flow equipment. Butterfly valves come in various designs and materials tailored for specific systems. They are recognized for their excellent flow control, tight shut-off capability, and versatility in a wide range of applications. Selecting the appropriate valve is essential for the success of any flow control system.

At CareWater, we offer a comprehensive range of advanced valve types. They meet strict industry requirements and provide low cost of ownership for end-users by improving costs, reducing downtime, and minimizing maintenance expenses. You can rely on CareWater’s butterfly valves to achieve comprehensive success in flow control.

Installation of a butterfly valve:

A butterfly valve is a valve with a circular body and a disc that rotates in the middle, connected to a shaft (metal rod). Rotating the shaft causes the disc to rotate. Several methods are used to rotate the shaft: for small diameters, a regular circular handwheel or a compression handle is used. For larger diameters, actuators of various types such as electrical, pneumatic, or hydraulic actuators are used. In both cases, a gear operator can be installed to facilitate disc rotation.

When is it preferable to use a butterfly valve?

Butterfly valves were originally used in situations where a completely tight shut-off was not necessary. However, over the years, these valves have been manufactured with relatively tight seals made of rubber or flexible materials that provide good closure similar to other types of valves. Butterfly valves are used in limited-space environments. Unlike gate valves, butterfly valves can be used for flow control or regulation in addition to fully open and fully closed positions. The pressure drop across a butterfly valve is small compared to a gate valve. The L/D ratio for this type of valve is about one-third of the L/D ratio for a gate valve. Butterfly valves are used in both large and small sizes and can be operated using a manual handwheel, a key, or a gear mechanism.

Choosing the right type of butterfly valve

Butterfly valves are essential in applications that require tight shut-off. The disc is opened and closed by rotating it with a low torque at a 90-degree angle, making it suitable for any compatible application. They tend to be more cost-effective and lightweight, making them preferred over other valves. Butterfly valves are often distinguished into three main types: zero-offset, double-offset, or triple-offset.

Zero-offset butterfly valves

These valves are designed to solve the seating problems that can occur between the disc and the seat of the butterfly valve. The valve stem and disc are placed in the center. A seal is created when the disc turns against the soft seat, resulting in full contact throughout the entire operating cycle. This valve can handle chemicals, coatings, food, some solids, and corrosive applications. One advantage is that most of the medium flowing through the valve does not come into contact with the body because the soft seat of the valve covers the body.

Double-offset butterfly valves

The double-offset design features the offset of the stem center from the disc and valve center. With this design, the valve disc can leave the valve seat quickly, greatly reducing unnecessary overpressure and friction between them. This type of design also helps reduce corrosion and extend the life of the valve. Reducing friction also allows for the creation of metal seats for these valves, expanding the range of applications for high-temperature butterfly valve applications.

Triple-offset butterfly valves

The triple-offset design eliminates friction between the seat and the sealing ring along the flow path. It reduces wear on the seat and seal and enhances cycle life. It is used in similar applications to gate valves. A metal seat, tight shut-off, and/or quarter-turn operation are required. However, triple-offset butterfly valves can open and close more quickly and can be operated repeatedly, even in emergency shutdown situations. This valve has low torque and is recommended for high and low-temperature applications.