The resilient-seal concentric butterfly valve is a common type of valve where the valve stem axis, the center of the butterfly plate, and the center of the valve body are located on the same axis. It uses elastic materials such as rubber for sealing, and the sealing pressure is generated by the elastic force formed by the interference fit between the butterfly plate and the bushing, achieving bidirectional sealing. This valve has a compact structure, low flow resistance, large flow area, and a near-linear flow characteristic, making it suitable for regulating media flow. The sealing ring is removable and replaceable, adaptable to different media requirements. It is commonly used for pipeline media control and flow regulation in petroleum, chemical, and water supply and drainage industries.
Advantages of Resilient-Seal Concentric Butterfly Valves
High Cost-Effectiveness
This is the most significant advantage of concentric butterfly valves. Compared to eccentric butterfly valves (such as double or triple eccentric), concentric butterfly valves have a simpler structure and relatively lower manufacturing requirements, thus typically resulting in a lower purchase price. The simple structure means easier disassembly and installation, lower technical requirements for maintenance personnel, and relatively lower costs for routine maintenance and parts replacement.
Simple Structure and Convenient Operation
Its structure is very intuitive, small in size, and lightweight, saving installation space and facilitating transportation and handling. The valve can be switched on and off simply by rotating the valve stem 90°. Due to the characteristics of its sealing structure, its operating torque is typically low, making it easy to operate manually or with an actuator.
Excellent Low-Pressure Sealing Performance
While it may not be as effective as hard-seal valves at high pressures, the resilient seal (usually rubber or PTFE) provides excellent sealing within its applicable range. In low-pressure conditions, the resilient seal ring effectively fills even the smallest gaps, achieving a tight seal and preventing media leakage. This elasticity also compensates for minor misalignments during pipeline installation or flange unevenness.
Wide Range of Applications (for Specific Conditions)
Due to the above characteristics, it is widely used in civil and industrial low-pressure applications. It is ideal for water treatment, HVAC, building water supply and drainage, irrigation systems, etc. It is suitable for common media such as air, water, and weak acids and alkalis.
Common Problems and Solutions for Resilient Seal Concentric Butterfly Valves
Drive System Failure (Unable to Transmit Torque)
Manual Drive: Bent/worn valve stem, loose connection between handle and valve stem;
Electric Drive: Short circuit in motor coil, damaged bearing, poor power cord contact;
Pneumatic Drive: Insufficient air pressure, solenoid valve malfunction, cylinder leakage.
Solutions
Manual: Straighten/replace the bent valve stem, tighten the handle connection;
Electric: Check the motor coil (replace if short-circuited), replace worn bearings, ensure good power cord contact;
Pneumatic: Check air pressure (must meet 0.4-0.6MPa), repair the solenoid valve, replace cylinder seals.
Mechanical Jamming (Butterfly Plate Cannot Rotate)
Debris (medium particles, rust, etc.) on the sealing surface/valve cavity is jamming the butterfly plate; aging/hardening/expansion of the elastic seal (rubber ring) causes it to jam against the valve body; deformed valve stem or excessive tightness with the bearing; misalignment of the butterfly plate (not concentric with the valve body), causing it to scrape the valve body during rotation.
Solutions
After closing the valve, flush through the bypass or disassemble the valve body for manual cleaning; select a suitable elastic seal for the medium (such as oil-resistant rubber or fluororubber) and install according to specifications; straighten the deformed valve stem or replace the severely worn valve stem; reinstall the butterfly plate, ensuring the valve stem, butterfly plate, and valve body are coaxial.
Installation or Medium Issues
Uneven tightening of valve body flange bolts causes valve body deformation, squeezing the butterfly plate; the medium contains particles/crystals (such as sewage or slurry), which accumulate and jam the butterfly plate over time; excessively high medium temperature causes aging and failure of elastic seals (such as softening and sticking of rubber rings).
Solutions
Tighten the flange bolts evenly (diagonally) to avoid valve body deformation; install a filter (≥100 mesh) before the valve and clean the valve cavity regularly; if the medium temperature is >80℃, use fluororubber or PTFE seals.
Seal Failure Leading to Jamming
Wear/crack of elastic sealing rings (such as O-rings or butterfly plate seals) allows the medium to seep into the valve stem gap, leading to corrosion and jamming.
Solution
Disassemble the valve, replace worn seals, and apply anti-rust grease (such as molybdenum disulfide) to the valve stem surface.
Summary
The failure of a resilient-seal concentric butterfly valve is often due to jamming or drive failure. Prioritize checking the drive system, removing debris, and inspecting the seals. Ensure proper installation (concentricity and even bolt tightening) to quickly restore function. If you purchased your valves from TEJI, please feel free to contact us if you encounter any issues with the valves not working. We will provide you with a solution promptly.
