Butterfly valves are commonly used in industrial processes to control the flow of liquids and gases. A double eccentric butterfly valve is a specific type of butterfly valve with improved sealing performance.
How Double Eccentric Butterfly Valves Work?
A double eccentric butterfly valve consists of a circular disc mounted on two shafts or “eccentrics.” As the disc rotates, it moves in an orbital motion rather than purely rotating.
- This orbital motion of the disc creates two sealing points instead of just one:
- The disc edge seals against the inner surface of the valve body.
- The face of the disc seals against the valve seat.
The dual sealing points provide better tightness and efficiency compared to standard butterfly valves. The double eccentric design also eliminates disc hammering and reduces friction, resulting in lower actuation torque requirements.
Advantages Of Double Eccentric Butterfly Valves
• Lower leakage – The double sealing points provide improved efficiency and tighter shut-off.
• Bi-directional sealing – Effective sealing in both flow directions.
• Reduced torque – The orbital motion reduces frictional torque needed to actuate the valve.
• Extended lifespan – Less wear and longer life expectancy compared to standard butterfly valves.
• Bubble-tight shutoff – Can achieve zero-leakage shutoff when required.
• Compact design – Eccentric shafts rotate within the valve body for a space-saving design.
• Easy maintenance – Simple design with easy-to-access parts.
Double Eccentric Butterfly Valves Are Suited For Many Industrial Applications
• Processes that require strict containment specifications prefer double eccentric butterfly valve due to their lower leakage rates resulting from the double sealing points.
• Valves that remain closed for long time periods benefit from the reliability of the double sealing points of double eccentric butterfly valves, providing an effective shut-off.
• Applications with alternating or bi-directional fluid flow are well matched to double eccentric butterfly valves since they can seal effectively in both flow directions.
• Large double eccentric butterfly valves experience reduced actuation torque requirements due to the orbital motion of the disc, making them suitable for applications with large valve sizes.
• The simpler design of double eccentric butterfly valves with fewer wear parts results in easier maintenance compared to triple offset butterfly valve designs.
• The reduced friction and wear that the orbital motion provides extends the operational lifespan of double eccentric butterfly valves, making them durable for long-term use.