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Butterfly valves are quite versatile ones. They can be used at multiples industrial applications, fluid, sizes, pressures, temperatures and connections at a relative low cost.
The development of this type of valve has been more recent than other ones. A major conviction on saving energy in the installations was an advantage for its introduction, due its head loss is small. At the beginning they were used in low pressure installations service, but technologic improvements, specially in the elastomer field let their extension to higher performances.
As any quarter turn valve, the operative of the butterfly valve is quiet easy. The closure member is a disc that turns only 90º; to be full opened/closed. This is a quick operation.
Few wear of the shaft, little friction and then less torque needed means a cheaper actuator. The actuator can be manual, oleo hydraulic or electrical motorized, with automation available.
Butterfly valves geometry is simple, compact and revolute, therefore it is a cheap valve to manufacture either saving material and post mechanization.
Its reduced volume makes easy its installation. Gate and globe valves are heavier and more complex geometry, therefore butterfly valve can result quiet attractive at big sizes regarding other types of valves.
The head loss is small as the flow goes aerodynamically around the disc when valve is full open. Although the head loss is slightly higher than in spherical and gate valves, because their flow sections are totally free from obstacles, it is clearly lower than in globe valves.
Butterfly valves can work with any kind of fluid, gas, liquid and also with solids in suspension. As a difference from gate, globe or ball valves, there are not cavities where solid can be deposit and difficult the valve operative.
Pressure and temperature are determinant and correlated designing factors. At a constant pressure, rising temperature means a lower performance for the valve, since some materials have lower capacity. As well gate, globe and ball valves, the butterfly valve can be manufactured with metallic seats that can perform at high pressure and extreme temperatures.