Introduction to butterfly valve

butterfly valve
Butterfly valve is a quarter turn rotary motion valve used to stop, regulate and start flow.
Butterfly valves are easy to open. Turn the handle 90 ° to fully close or open the valve. Large butterfly valves are usually equipped with a so-called gearbox, which connects the handwheel to the valve stem through gears. This simplifies the operation of the valve, but at the cost of speed.
Type of butterfly valve
Butterfly valves have short round bodies, discs, metal to metal or soft seats, top and bottom shaft bearings, and stuffing boxes. The structure of butterfly valve body is different. A common design is a wafer type installed between two flanges. Another type of lug wafer design is fixed between two flanges by bolts that connect two flanges and pass through holes in the valve housing. Butterfly valves can even be supplied with flanged, threaded and butt welded ends, but are not often used.
Butterfly valves have many advantages over gate, globe, plug and ball valves, especially for large valve applications. Saving weight, space and cost is the most obvious advantage. Maintenance costs are usually low because the number of moving parts is small and there is no container for collecting fluids.
Butterfly valve is especially suitable for handling large flow of liquid or gas under relatively low pressure, as well as slurry or liquid with a large number of suspended solids.
Butterfly valve is based on the principle of pipeline damper. The flow control element is a disc of approximately the same diameter as the inner diameter of the adjacent tube, which rotates on a vertical or horizontal axis. When the disc is parallel to the line, the valve is fully open. When the disc is close to the vertical position, the valve closes. In order to throttle, the middle position can be fixed in place through the handle locking device.


Typical application of butterfly valve
Butterfly valves can be used in many different fluid services and perform well in slurry applications. Here are some typical applications of butterfly valves:
✱Cooling water, air, gas, fire prevention measures, etc
✱Mud and similar services
✱ vacuum service
✱High pressure and high temperature water and steam service
Advantages of butterfly valve
✱the compact design requires much less space than other valves
✱ light weight
✱ faster operation takes less time to turn on or off
✱ available in extra large sizes
✱ low pressure drop and high pressure recovery
Disadvantages of butterfly valve
✱throttling service is limited to low differential pressure
✱Cavitation and Cho flow are two potential problems
✱ disk motion is not guided and is affected by flow turbulence

Post time: Jun-11-2020