Language
The differences between centerline butterfly valves and eccentric butterfly valves
1. Basic structure and principle
The centerline butterfly valve is symmetrically designed, with the center axis of the valve plate coinciding with the axis of the pipeline. It achieves sealing by the compression deformation of the elastic valve seat (usually rubber). Its structure is simple and the manufacturing cost is low, but the valve plate will always rub against the valve seat during the opening and closing process, which is prone to wear. The eccentric butterfly valve improves this defect through the design of axial offset (single eccentric, double eccentric or triple eccentric): single eccentric moves the rotating shaft away from the center line of the sealing surface; double eccentric adds axial offset on this basis; triple eccentric further adopts a beveled surface sealing design, allowing the valve plate to be disengaged from contact at the instant of opening, significantly reducing wear.
2. Performance Comparison and Application Scenarios
The mid-line butterfly valve is suitable for clean media such as water and air with a pressure of ≤1.6MPa and a temperature below 120℃. It is commonly used in building water supply and drainage systems and HVAC systems. The rubber valve seat has a lifespan of approximately 2-3 years under frequent opening and closing conditions. In the eccentric butterfly valve, the double eccentric type can handle media containing trace particles (such as wastewater treatment), with a lifespan of up to 5-8 years; the three eccentric type uses a metal sealing pair (such as stainless steel + hard alloy), with a pressure rating of PN40 and a temperature limit of 650℃, and is particularly suitable for high-pressure and high-temperature working conditions in power stations and petrochemical industries, with a lifespan of up to 10 years.
3. Economic Analysis of Model Selection
Taking the DN300 valve as an example, the price of the centerline butterfly valve is approximately 2,000 - 5,000 yuan, while the price of the three-sealed eccentric butterfly valve is as high as 20,000 - 50,000 yuan. However, considering maintenance costs: the centerline valve may need to be replaced annually in industrial environments, while the three-sealed eccentric valve can be used continuously for 5 years without maintenance. For industrial systems with more than 10,000 opening and closing operations per year or strong medium corrosiveness, the total life cycle cost of the three-sealed eccentric butterfly valve is actually lower. It is recommended that ordinary civilian systems choose the centerline type, while industrial systems with continuous production should prioritize the three-sealed design. The products of Zhongguan Valve have extended the service life of the centerline butterfly valve to 5 years through optimized design and precise processing, and the three-sealed butterfly valve can reach 15 years, significantly reducing the overall usage cost for users.
