Whether regulating flow or achieving on/off operation, butterfly valves play a vital role in fluid handling systems across industries. However, not all butterfly valves are alike – their designs vary to suit diverse applications and media. Let’s explore some common butterfly valve types.
Soft Sealing Butterfly Valves
For gentle shut-off of liquids and gases, soft sealing butterfly valves feature a resilient disc edge seal contacting the valve body. This “bubble-tight” sealing permits precise throttling or gradual closure. Fabric, EPDM, FKM, PTFE and other elastomer materials conform well without damaging sealing surfaces even after frequent use. Suitable for clean services, soft seating extends component life in demanding services.
Cast Iron Butterfly Valves
Ductile or grey cast iron construction provides durability and tight shut-off for corrosive or abrasive slurries and fluids containing solids. Thick castings and rugged sealing withstand interior and exterior corrosion while handling pressure and temperature fluctuations. Reinforced discs add strength for high-velocity or high-pressure services prone to erosion. Flanged, wafer, or lug ends couple cast iron butterfly valves into almost any piping system.
Eccentric Butterfly Valves
Rather than the standard concentric disc, eccentric butterfly valves feature an off-center disc enabling modulation from a quarter-open position onward. This prevents throttling that can induce turbulence and is ideal for modulated flow control of liquids in open channel hydraulics. The non-concentric sealing path eases operation for viscous or sticky media that may adhere to concentric discs.
Manually operated valves actuate via lever, gear or electric motor, while pneumatic or hydraulic actuators automate remote applications. Integral indicating handles display internal disc position at a glance. Fugitive emissions seals on gas service versions protect the environment. Wafer, lug and flanged ends suit varied installation needs.
By comprehending such variants, engineers can specify the optimally suited butterfly valve design factoring inherent component capabilities against application parameters like temperature, pressure, media properties and required flow characteristics. This matching helps deliver maximum performance reliability for divergent fluid handling duties.
In summary, the versatility inherent to different butterfly valve types from soft seating to cast iron to eccentric designs provides solutions for a spectrum of industries and fluid services worldwide. Proper selection streamlines projects by resolving specified operational needs.