How Do Butterfly Valves Differ From Gate Valves?

In valve pipelines, both gate valves and butterfly valves are used to control the opening and closing of flow. However, gate valves can only be fully opened or fully closed, making them unsuitable for flow regulation. In contrast, butterfly valves can regulate flow by adjusting the angle of the valve disc. Today, we will compare these two types of valves to help you better understand them and determine how to use them most effectively.

Butterfly Valve Design and Features

Butterfly Valve Type

• Lug Type: Connected to the pipeline through threaded holes, suitable for single-end disassembly.

• Flanged Type: Equipped with built-in flanges, connected to the pipeline using bolts, ideal for secure installations.

• Wafer Type: Uses special flanges and double-headed bolts for connection, offering a compact design.

• Butt Weld Type: Pipes or fittings are welded directly to the valve body, suitable for high-pressure systems.

High Performance Butterfly Valve

• Double Eccentric Butterfly Valve: Suitable for medium pressure and temperature conditions.

• Triple Eccentric Butterfly Valve: Offers higher sealing performance and can handle more demanding temperature and pressure conditions.

High-performance eccentric butterfly valves are professionally designed to withstand applications with higher temperature and pressure requirements, though they are relatively more expensive.

Butterfly valve operating method

Butterfly valves belong to the quarter-turn valve category, allowing operation by rotating the handle 90°. In the fully closed position, the valve disc is perpendicular to the flow direction, while in the fully open position, the disc is parallel to the flow. Partially opening or closing the disc enables proportional flow control or throttling.

However, as the disc remains perpendicular to the flow direction when opened, some pressure loss and minor turbulence are inevitable. Additionally, butterfly valves are not well-suited for handling media containing suspended solids, grit, or viscous substances. These materials can accumulate on the disc, potentially affecting the valve's ability to close tightly.

Gate Valve Design and Features

Gate Valve Type

• Wedge Gate Valve: Features a wedge-shaped design with an angled sealing surface, providing strong sealing performance.

• Parallel Gate Valve: Designed with parallel sealing surfaces, suitable for low-pressure systems.

• Knife Gate Valve: Has a flat plate with a sharp edge, specifically designed for handling slurry or suspended solids, capable of cutting through deposits.

Classification by Stem Movement: Rising Stem and Non-Rising Stem Gate Valves

• Rising Stem Gate Valve: Provides a visual indication of the valve position but requires more vertical space above the valve for operation.

• Non-Rising Stem Gate Valve (NRS): Lower cost with fewer components, suitable for limited-space installations, but does not offer the visual position indication provided by rising stem models.

Gate valve operating method

Gate valves are multi-turn valves, meaning the handwheel must rotate more than 360° to fully open or close the valve. The rotation of the valve stem raises or lowers the gate or wedge, starting or stopping the flow of fluid. When the gate is raised, it allows fluid to pass through, and when lowered, it blocks the flow.

It is important to note that most gate valves are not suitable for throttling operations. Extended throttling can cause vibration and resonance within the valve, leading to damage to seals, gaskets, and other critical components.

When fully open, the gate valve's disc completely clears the flow path, causing minimal flow obstruction and nearly no pressure loss. For handling slurry, suspended solids, or grit, the knife gate valve is a specialized type of gate valve. Its sloped-edge disc effectively cuts through accumulated materials and reduces the torque required to fully close the valve.

Comparison of Pros and Cons: Butterfly Valves vs. Gate Valves

Comparison Item	Butterfly Valve	Gate Valve
Cost	Lower, suitable for large-diameter pipelines	Higher, especially for large diameters where costs increase
Installation Space	Compact and lightweight	Bulky and occupies more space
Weight	Lightweight, easy to install and maintain	Heavy, requiring additional support
Flow Regulation	Can be used for throttling, but with limited precision	Only suitable for fully open or fully closed positions
Flow Resistance	Higher, may cause turbulence	Lower, with minimal pressure loss
Pressure Capacity	Suitable for medium pressure	Suitable for high-pressure applications
Operation Speed	Quick opening and closing but susceptible to water hammer	Slower opening and closing, ideal for less frequent operations

Gate Valves vs. Butterfly Valves: Frequently Asked Questions (FAQ)

1. How to Choose Between a Butterfly Valve and a Gate Valve?

Choose a Butterfly Valve: When you need quick opening and closing, space-saving installation, or are operating in medium to low-pressure conditions.

Choose a Gate Valve: When precise sealing is required, or for high-temperature, high-pressure applications, or systems needing bi-directional and uninterrupted flow.

2. When Can a Butterfly Valve Replace a Gate Valve?

Low-Pressure, Medium to Low-Temperature Applications: For water supply pipelines, HVAC systems, or low-pressure conditions, butterfly valves can easily substitute gate valves.

Limited Installation Space or Weight-Sensitive Applications: Butterfly valves are ideal for compact designs, such as on ships or mobile equipment.

Frequent Operation or Flow Regulation Needs: The quick operation and flow control capabilities of butterfly valves make them better suited for such scenarios.

3. When Should a Gate Valve Be Chosen Over a Butterfly Valve?

• Zero Leakage for Critical Media: Use gate valves when handling expensive or toxic media that require zero leakage.

• High-Pressure, High-Temperature Environments: Ideal for steam pipelines or boiler systems.

• Full Bore Design to Minimize Pressure Loss: Gate valves are preferred when a pipeline demands full bore to reduce pressure loss.

• Long-Term Closure Applications: Gate valves provide stable sealing performance for systems requiring long-term closure.

• Bi-Directional Flow Systems: Gate valves offer reliable sealing for bi-directional flow.

TFW is a professional manufacturer of butterfly valve and gate valve, offering a wide range of standard valves as well as custom designs to meet exact customer specifications. If you have any further questions, please feel free to contact us.