Applications and Limits of Butterfly Valves as Control Valves

Yes, butterfly valves can be used as control valves, but their suitability depends on various factors including the specific application requirements and budget constraints. Let's delve into when and how a butterfly valve can be appropriately used as a control valve.

Balancing Cost and Accuracy

Before choosing a control valve for your application, you should consider:

• Application Requirements: What is the valve’s purpose in the process?
• Control Precision: How much control accuracy is required?
• Budget Constraints: What is your project’s budget?

Butterfly valves can serve as control valves and are generally less expensive than other types, like globe valves. However, they offer limited accuracy and are only suitable if your application can tolerate this limitation. The choice of butterfly valve type—such as resilient seated or high-performance—depends on the specific process conditions. Other factors to consider include:

• Lower Installation Costs: Butterfly valves are typically cheaper to install.
• Compact Size and Weight: They are smaller and lighter, requiring fewer supports and braces.
• Ease of Maintenance: With fewer parts, they are simpler to maintain.

Limitations of Butterfly Valves as Control Valves

While butterfly valves have their advantages, they are not suitable for every application and should not be chosen solely to reduce costs. Some limitations include:

• Flow Characteristics: Most butterfly valves have a non-linear flow characteristic, with minimal flow until the valve is opened to about 40 degrees. Beyond this point, the flow increases sharply, which may not be suitable for applications requiring precise flow control.
• Cavitation and Pressure Drop: Butterfly valves often have poor recovery factors, leading to issues with cavitation and permanent pressure drops during flow throttling.
• Precision and Repeatability: Achieving and maintaining precise control is difficult, especially at low flow rates.

When to Use Butterfly Control Valves

Although butterfly valves are not ideal for all applications, particularly those requiring precise control, they can still be a viable option in certain scenarios:

• Space Constraints: They are excellent for applications with limited space due to their compact size.
• Flow Throttling and Regulation: They offer effective flow control with less pressure loss compared to globe valves.
• Cost-Effective Solution: In many cases, butterfly valves can replace other control valves, providing similar functionalities at a lower cost.

Conclusion

Butterfly valves can be a practical choice for control applications where precision is not paramount, and budget or space constraints are significant factors. They offer stable, modulating flow control with minimal maintenance needs and can reduce risks like leaks. However, it’s crucial to assess whether their limitations align with your application requirements before making a decision.

For more detailed advice on using butterfly control valves in your next project, consider scheduling an appointment or reaching out on social media.