1. Structural design
Concentric butterfly valve
The valve stem axis, the butterfly plate center and the valve body center completely overlap to form a three-line coaxial structure
The butterfly plate and the valve seat are always in direct contact, and the sealing surface is continuously squeezed and scraped during rotation
Triple eccentric butterfly valve
On the basis of double eccentricity (the valve stem deviates from the butterfly plate center and the valve body center), a third eccentricity is added: the cone axis of the butterfly plate sealing surface is tilted to the valve body axis
The butterfly plate sealing surface changes from a circle to an ellipse, resulting in an asymmetric shape of the sealing contact surface
2. Sealing principle
Concentric butterfly valve
Sealing is achieved by relying on the deformation of elastic materials (such as rubber, polytetrafluoroethylene)
The sealing surface is in surface contact, and the sealing effect is produced by continuously squeezing the valve seat material
Triple eccentric butterfly valve
The sealing surface is in surface contact, and the sealing effect is produced by continuously squeezing the valve seat material
Triple eccentric butterfly valve Concentric butterfly valve
Adopts the principle of torque sealing, relying on the contact surface pressure between the butterfly plate and the valve seat to achieve sealing, rather than elastic deformation of the material
The sealing pair is a hard sealing structure (metal material), and the contact track is oblique cone
3. Performance characteristics
Concentric butterfly valve
Advantages: simple structure, low cost, suitable for low pressure and normal temperature conditions
Disadvantages:
Long-term extrusion causes rapid wear of the valve seat and requires frequent replacement
Limited by sealing materials, poor temperature resistance (generally ≤120℃)
Triple eccentric butterfly valve
Advantages:
The butterfly plate and the valve seat are completely separated during opening and closing, achieving zero friction operation
High temperature resistance (up to 600℃ or more) and significantly improved pressure bearing capacity
Supports two-way sealing, leakage level up to ANSI Level VI
Disadvantages: high manufacturing cost and strict requirements on processing accuracy
4. Application Scenarios
Concentric Butterfly Valve
Mainly used in low-pressure and normal-temperature systems such as water supply and drainage, HVAC, etc., and can be wiped clean when the medium contains particulate matter
Triple-eccentric Butterfly Valve
Suitable for harsh working conditions of high temperature and high pressure (such as power stations and petrochemicals), especially for corrosive media or supercritical fluid control with zero leakage requirements
Through the triple eccentric design, the triple eccentric butterfly valve has achieved a comprehensive innovation from structure to performance, solving the contradiction between high pressure and high temperature and sealing life of traditional butterfly valves.
