Butterfly valves are widely used in industries such as petroleum, gas, chemical, water treatment, and cooling water systems in thermal power plants. There are two commonly used butterfly valves: clamp type butterfly valve and flange type butterfly valve.

A valve with a butterfly plate rotating around a fixed axis inside the valve body is called a butterfly valve. Butterfly valve, also known as flap valve, is a structurally simple regulating valve that can also be used for on/off control of low-pressure pipeline media. It refers to a valve whose opening and closing components are disc-shaped butterfly plates that can rotate around the axis inside the valve body.

Basic structure of butterfly valve

Butterfly valves are mainly composed of valve body, butterfly plate, valve stem, sealing ring and other components. The closing component of the valve is a disc-shaped butterfly plate, which can rotate 90 degrees around its axis. The butterfly axis is perpendicular to the direction of fluid flow. When the driving handle rotates, it drives the valve stem and butterfly plate to rotate together, causing the valve to open or close. The butterfly plate of the butterfly valve is disc-shaped, and the sealing seat is a P-type rubber ring, which ensures the sealing performance of the valve and has good corrosion resistance. However, it is not suitable for pipelines with high-temperature media. Some types of butterfly valves have their valve seats directly made on the valve body, or have wear-resistant and corrosion-resistant materials welded onto the valve body before processing the valve seat. Butterfly valves can be used as globe valves in pipelines.

Butterfly valves can be divided into offset plate, vertical plate, inclined plate, and lever type according to their structural forms. According to the sealing form, it can be divided into two types: relatively sealed type and hard sealed type. Soft sealing type generally uses rubber ring sealing, while hard sealing type usually uses metal ring sealing. According to the connection type, it can be divided into flange connection and clamp connection; According to the transmission mode, it can be divided into manual, gear transmission, pneumatic, hydraulic, and electric.

Characteristics of butterfly valve

(1) Simple structure and small external dimensions. Due to its compact structure, short length, small volume, and light weight, it is suitable for large-diameter valves.

(2) The fluid resistance is low, and when fully opened, the effective flow area of the valve seat channel is larger, resulting in lower fluid resistance.

(3) Easy and fast opening and closing, good adjustment performance, the butterfly plate can be opened and closed by rotating 90 °. By changing the rotation angle of the butterfly plate, the flow rate can be controlled in stages.

(4) The opening and closing torque is relatively small, and due to the fact that the butterfly plates on both sides of the shaft are subjected to the same medium effect, the direction of torque generated is opposite, making opening and closing more effortless.

(5) Low pressure sealing performance is good, and the sealing surface material is generally made of rubber, plastic, and has good solid sealing performance. Due to the limitations of the sealing ring material, the operating pressure and temperature range of butterfly valves are relatively small. But the operating pressure and temperature range of hard sealed butterfly valves have been greatly improved.