A butterfly valve is a flow regulating valve. A butterfly valve is a valve in which the sealer rotates about an axis at right angles to the direction of flow, and when opened, the fluid bypasses the sealer.

In other words, the butterfly valve is composed of a disc with the rod of the disc or disc passing through the middle. After opening, the valve flap pivots 90 degrees in the valve hole to align with the flow, thus forming an almost unrestricted flow path. The butterfly valve has a rotation angle of 90 degrees, and its operation is similar to a spherical valve and can be quickly closed.

Butterfly valves have been popular for many years due to the thin profile between the flanges, making them lighter in weight and smaller in installation area. Compared with other valve designs, this compact design can usually reduce the initial cost of these valves.

There are different types of butterfly valves, and each type has unique design features and applications. Each type is determined by the direction of the valve stem relative to the valve flap and the seat angle at which the valve flap closes.

The basic butterfly valve design is often referred to as a concentric or elastic seat butterfly valve. In this type of valve, the valve stem is centered in the middle of the valve disc and the valve plate is in the center of the pipe hole. The valve usually has a rubber (or elastic) valve seat and relies on a disc that is in high contact with the valve seat to achieve sealing.

The Ronnie Shield butterfly valve is a durable elastic seat valve with an integrated valve body that can reduce weight and increase strength. The unique design of the valve stem hole on the valve disc can ensure that the stem journal is dry, and the hard back valve seat makes the installation simple, reliable operation, and can be replaced on site without special tools. It has been proven that Ronnie Shield butterfly valves are the choice for industrial and commercial applications.

In a single eccentric butterfly valve, the stem is behind the flap. Due to the development of double eccentric valves or high-performance valves, there are few such valves on the market today. The single offset of the valve stem causes the valve flap to contact the valve seat, moving the valve seat three to four degrees to the left, thereby reducing the contact of the valve seat and extending the service life of the valve.

Double-offset or high-performance butterfly valves have flaps with two offsets and a maximum pressure rating of 1480 psi. Similar to the single offset design, the rod is located behind the disc. With the help of a high-performance butterfly valve, the second eccentric rod will again move from the center of the flap to one side. This offset geometry allows the 90-degree disc rotation to "friction" onto the valve seat during 90-degree rotation.

Double eccentric butterfly valves are used in systems requiring higher pressure resistance. The valve flap is located in the center of the pipe hole and is arranged to improve the sealing ability and reduce the wear on the valve. The high-performance butterfly valve adopts a cost-effective, lightweight design, which is very suitable for processing water, oil, steam and gas. The corrosion resistance of the Ronnie Shield butterfly valve, single-component thrust bearing/disc gasket reduces body wear and helps ensure that the disc is properly centered in the valve hole.

Both flexible butterfly valves and high-performance butterfly valves can be operated by handles, gears or actuators. These devices move the valve disc to the position to fully close or fully open the valve. Elastic and high-performance butterfly valves are mainly used in the water, chemical and petrochemical industries, but can also be used in fuel processing systems, power and many other applications.

One type of butterfly valve is a triple eccentric butterfly valve (also known as TOV or TOBV). This butterfly valve is suitable for difficult services that require reliable performance under demanding conditions. Just like a double offset valve, the stem is behind the flap and is offset to one side (double offset). The third offset is the geometry of the seat surface. The surface of the base forms a conical shape of a disc and a valve seat, the wedge is wedged into the valve seat, and the contact between the sealing surfaces is very small until it is completely closed. By reducing the amount of contact between the valve seat and the flap, the seal becomes more effective and extends the life of the valve.

TOV is usually metal seated, unlike single and double eccentric butterfly valves. Ronnie Shield TOV adopts metal valve seat design, which can achieve two-way zero leakage* to achieve extreme service. The true three-eccentric geometry enables airtightness* sealing to create a fully bidirectional zero leakage* globe valve.

Tri-eccentric butterfly valves are commonly used in steam, chemical, refining, and offshore oil and gas applications at temperatures up to 1400°F (760°C). The sturdy metal seat can also withstand a high degree of wear and impact, and through proper material selection, it can also be used for low temperature services, such as LNG and NPG facilities.