Butterfly Valves vs Globe Valves

Butterfly valves and globe valves are two common types of valves used in many industries, including oil and gas, water treatment, chemical processing, and HVAC systems. While they both serve the same purpose of controlling fluid flow, they have distinct differences in design, functionality, and performance. In this article, we will compare butterfly valves and globe valves in detail to help you make an informed decision on which valve type to use in your application.

What is a Butterfly Valve?
A butterfly valve is a quarter-turn valve that controls flow by rotating a disc or a vane in the center of the valve body. The disc is connected to a stem that passes through the valve body and is connected to a handle or actuator outside the valve. When the handle or actuator is turned, the disc rotates either parallel or perpendicular to the flow direction, allowing or restricting fluid flow through the valve. Butterfly valves are available in a range of sizes, from 1 inch to over 100 inches, and are commonly used in large-diameter applications.
Butterfly valves are classified into two types: wafer and lug. Wafer butterfly valves are sandwiched between two flanges and held in place by bolts, while lug butterfly valves have threaded inserts or lugs that are bolted to the valve body. Both types of butterfly valves are designed for quick operation and are preferred over gate valves in applications where fast shut-off is required. They are also lightweight and compact, making them ideal for applications where space is limited.

Advantages of Butterfly Valves

1. Quick operation - Butterfly valves require only a quarter turn to fully open or close, making them ideal for applications where fast shut-off is necessary.
2. Lightweight and compact - Butterfly valves are smaller and more lightweight than other types of valves, making them ideal for applications where space is limited.
3. Low pressure drop - Butterfly valves have a low pressure drop compared to other types of valves, making them ideal for applications where a high flow rate is required.
4. Cost-effective - Butterfly valves are less expensive than other types of valves, making them an excellent option for applications where cost is a significant factor.

Disadvantages of Butterfly Valves

1. Limited temperature range - Butterfly valves are typically limited to temperatures below 500°F, making them unsuitable for high-temperature applications.
2. Poor throttling performance - Butterfly valves do not have precise throttling capabilities, making them unsuitable for applications where precise flow control is required.
3. Limited sealing capabilities - Butterfly valves have a limited sealing capability compared to other types of valves, making them unsuitable for applications where a high level of tightness is required.

What is a Globe Valve?

A globe valve is a linear motion valve that controls flow by lifting or lowering a disc or a plug in the center of the valve body. The disc is connected to a stem that passes through the valve body and is connected to a handwheel or actuator outside the valve. When the handwheel or actuator is turned, the stem moves up or down, lifting or lowering the disc or plug and controlling fluid flow through the valve. Globe valves are available in a range of sizes, from 1/2 inch to over 24 inches, and are commonly used in applications where precise flow control is required.
Globe valves are classified into two types: T-pattern and Y-pattern. T-pattern globe valves have a linear flow path and are suitable for applications where a straight flow path is required. Y-pattern globe valves have an angled flow path and are suitable for applications where a high flow rate is required. Globe valves are also available in different materials, including cast iron, carbon steel, stainless steel, and brass, and can be customized to meet specific application requirements.

Advantages of Globe Valves

1. Precise flow control - Globe valves are capable of precise flow control due to their linear motion design. They are ideal for applications where precise regulation of flow is necessary, such as in chemical processing and water treatment.
2. Good throttling performance - Globe valves have a good throttling performance, allowing for precise flow control over a range of flow rates. They can also be equipped with a range of trim materials to enhance their throttling capabilities.
3. Good sealing capabilities - Globe valves have a good sealing capability due to the linear motion of the disc or plug. This makes them ideal for applications where a high level of tightness is necessary.
4. Wide temperature range - Globe valves are capable of operating at high temperatures, making them suitable for high-temperature applications.

Disadvantages of Globe Valves

1. Slow operation - Globe valves require multiple turns of the handwheel or actuator to fully open or close, making them unsuitable for applications where fast shut-off is necessary.
2. Bulky and heavy - Globe valves are larger and heavier than other types of valves, making them unsuitable for applications where space is limited.
3. High pressure drop - Globe valves have a high pressure drop compared to other types of valves, making them unsuitable for applications where a high flow rate is necessary.

Butterfly Valve vs Globe Valve: Key Differences

1. Design - Butterfly valves have a disc or vane that rotates around a central axis, while globe valves have a disc or plug that moves up and down in a linear motion.
2. Operation - Butterfly valves require a quarter turn to fully open or close, while globe valves require multiple turns of the handwheel or actuator.
3. Flow control - Butterfly valves do not have precise throttling capabilities, while globe valves are capable of precise flow control.
4. Pressure drop - Butterfly valves have a lower pressure drop than globe valves.
5. Temperature range - Butterfly valves are limited to temperatures below 500°F, while globe valves are capable of operating at higher temperatures.
6. Sealing capabilities - Globe valves have a better sealing capability than butterfly valves.
7. Cost - Butterfly valves are generally less expensive than globe valves.

Conclusion

Both butterfly valves and globe valves have their own unique advantages and disadvantages, and the choice of which valve to use in a particular application depends on several factors, including the type of fluid, the flow rate, the temperature range, and the required level of precision in flow control. Butterfly valves are ideal for applications where quick shut-off is necessary, while globe valves are ideal for applications where precise flow control is required. Ultimately, the decision between butterfly valves and globe valves comes down to the specific requirements of the application and the trade-offs between cost, performance, and reliability.