Eccentric butterfly valves have several disadvantages, including:

1. Limited Shut-off Capability: They may not provide a complete seal,  eccentric butterfly valve manufacturers  especially in high-pressure applications, which can lead to leaks.

2. Torque Requirements: The design may require higher torque to operate than other types of valves, potentially necessitating more powerful actuators.

3. Wear and Tear: The eccentric design can lead to uneven wear on the sealing surfaces, which can reduce the valve's lifespan.

4. Flow Characteristics: They may not offer the best flow characteristics, potentially causing turbulence and pressure drops in certain applications.

5. Sensitivity to Installation: Proper alignment during installation is crucial; misalignment can lead to operational issues and increased wear.

6. Limited Temperature and Pressure Ratings: They may not be suitable for extreme temperatures or pressures compared to other valve types.

7. Maintenance: Regular maintenance may be required to ensure proper operation, especially in demanding environments.

8. Cost: They can be more expensive than simpler valve designs, both in terms of initial investment and maintenance costs.

These factors should be considered when deciding whether to use an eccentric butterfly valve in a specific application.