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Contact SupplierA butterfly valve is a shut-off valve with a relatively simple construction. In closed position, the disc blocks the valve bore while in open position, the disc is turned to allow flow. A quarter turn takes the valve from fully open to fully closed position, or opposite, and thus the butterfly valve allows for quick opening and closure.
Butterfly valves can be used for a broad range of applications within water supply, wastewater treatment, fire protection and gas supply, in the chemical and oil industries, in fuel handling systems, power generation etc. Some of the advantages for this type of valve are the simple construction not taking up too much space, and the light weight and lower cost compared to other valve designs.
The valves can be operated by handles, gears or actuators according to any specific need.
Main design of butterfly valves | Â | Â |
The butterfly valve can be centric or eccentric. On a centric (concentric) butterfly valve the stem is centered in the middle of the disc and the disc centered in the bore. The eccentric butterfly valve has one or more stems (stub shafts) located offset from the center according to the categories of single, double and triple offset valves. |
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The butterfly valve consists of only four main components: body, disk, stem and seat.
Butterfly valve body:Â Butterfly valves generally have bodies that fit between two pipe flanges, the most common being lug and wafer body design.
Butterfly valve disk: The disk is how the valve stops flow – it is equivalent to a plug in a plug valve, a gate in a gate valve or a ball in a ball valve. There are variations in disk design and orientation in order to improve flow, sealing and/or operating torque.
Butterfly valve Stem:Â The stem of the butterfly valve may be a one-piece shaft or a two-piece (split-stem) design. The stem in most resilient seated designs is protected from the media, thus allowing an efficient selection of material with respect to cost and mechanical properties.
Butterfly valve Seat:Â The seat of a resilient-seat butterfly valve utilises an interference fit between the disk edge and the seat to provide shutoff. The material of the seat can be made from many different elastomers or polymers. The seat may be bonded to the body or it may be pressed or locked in.
Butterfly valves are easy and fast to open.A 90° rotation of the handle provides a complete closure or opening of the valve. Large Butterfly valves are usually equipped with a so-called gearbox, where the handwheel by gears is connected to the stem. This simplifies the operation of the valve, but at the expense of speed.
Butterfly valves are relatively inexpensive to build.Butterfly valves require less material due to their design. The most economical is the wafer type that fits between two pipeline flanges. Another type, the lug wafer design, is held in place between two pipe flanges by bolts that join the two flanges and pass through holes in the valve’s outer casing. Furthermore, common Butterfly Valves materials are often less expensive.
Butterfly valves have less space requirements.This is due to their compact design which requires considerably less space, compared to other valves.