The Fruitful Evolution Route Of Eccentric Butterfly Valve

Oct 23, 2023 | News

Butterfly valves control the flow of fluid in a pipe using a disc attached to a central shaft. This disc controls the amount of fluid passing through the valve by creating a variable orifice.

Butterfly valves can be classified according to the alignment of the flap relative to the valve body:

The early butterfly valve is the most traditional concentric butterfly valve(zero eccentric butterfly valve). Because it cannot withstand high temperature and high pressure and has large leakage, its application range is greatly restricted. In order to meet the requirements of various working conditions, butterfly valves have evolved from concentric to single eccentric butterfly valve, double eccentric butterfly valve and triple eccentric butterfly valve.To show it in a line Intuitively:

① lConcentric butterfly valve

② lSingle eccentric butterfly valve

③ lDouble eccentric butterfly valve

④ lTriple eccentric butterfly valve

Today  TWT,China would like to introduce to buyers the evolution route of butterfly valve eccentricity, and the double eccentric butterfly valve will be our leading role.

Evolution of butterfly valve eccentricity

Earliest concentric butterfly valve

The design features of concentric rotary valves are that the axis of the valve stem, the center of the rotary plate and the center of the body are in the same position, the design is simple and easy to manufacture. Unfortunately, the butterfly plate and valve seat are always crushed and scratched, which creates a lot of resistance and wears out quickly.

The first eccentricity

In order to solve the extrusion problem between the disc plate and the valve seat of the concentric rotary valve, a single eccentric rotary valve is manufactured. The design feature is that the axis of the valve stem deviates from the centre of the butterfly plate, so that the upper and lower ends of the butterfly plate are not the axis of rotation of the butterfly. Spray and reduce the excessive extrusion between the upper and lower ends of the butterfly plate and the valve seat. However, because the single eccentric design only reduces but does not eliminate the scratching phenomenon between the disc plate and the valve seat to a certain extent during the entire valve switching process, its application scope is similar to that of the concentric rotary valve, so it is not widely used.

The second eccentricity

Based on the single eccentric butterfly valve, the double eccentric butterfly valve is currently widely used. The structural feature is that the valve stem axis deviates from the center of the butterfly plate and the center of the valve body.

The third eccentricity

The third eccentricity of the throttle body has introduced some major changes: the seal structure has been significantly changed from a position seal to a torque seal. This means that it does not rely on the elastic deformation of the valve seat to achieve the sealing effect, but relies entirely on the pressure on the contact surface of the valve seat. This sealing structure allows the triple eccentric butterfly valve to achieve a VI level of sealing, achieving true zero leakage. At the same time, the triple eccentric butterfly valve uses a metal valve seat to achieve high heat resistance. At this stage of development, the problems of butterfly valve leakage and high temperature resistance have finally been solved.


Important roles of double eccentric butterfly valves

Double eccentric butterfly valves are widely used in fluid piping systems for control and containment in water supply and sewerage, wastewater, construction, petroleum, chemical, textile, paper, hydropower, metallurgy, energy and other projects.

Double eccentric butterfly valves are widely used in chemical industry systems such as environmental control for transport, mixing, filtration, dehydration and other applications. In the chemical industry, double-centre butterfly valves are mainly used for flow regulation and breakage control in corrosive, high temperature, high pressure, high viscosity and particulate media.

TWT,China produces high quality double eccentric butterfly valves,as long as you are in need of a double eccentric butterfly valve,TWT is a worthy choice.

Why are double eccentric butterfly valves widely used

The double eccentric effect allows for rapid separation of the slide plate from the valve seat after the valve is opened, which largely eliminates excessive compression and scrubbing between the slide plate and valve seat, reduces opening resistance and reduces valve seat wear. Greater durability. Friction is greatly reduced and this also provides the option of using a metal valve seat for the double eccentric gate valve, opening up its use in high temperature areas.

However, because the sealing principle is a positional sealing structure, that is, the sealing surface of the butterfly plate and the valve seat is in line contact, and the elastic deformation caused by the butterfly plate extruding the valve seat produces a sealing effect, so the requirements for the closing position are very high (especially for metal valves). valve seat), so the pressure-bearing capacity is still low.

In general, the double eccentric butterfly valve is already a type of butterfly valve with obvious advantages. The industry calls it a high-performance butterfly valve. TWT,China think this is a butterfly valve that is very worthy of buyers to consider purchasing,and provides high quality double eccentric butterfly valve.