Butterfly Valve

What is a Butterfly Valve?

A Butterfly Valve is a quarter-turn rotational motion valve used to stop, regulate, and start fluid flow. It consists of a disc mounted on a rotating shaft. When the valve is closed, the disc is turned so that it completely blocks off the passageway. When the valve is fully open, the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the fluid. The valve may also be opened incrementally to throttle flow.

Key Features and Advantages

• Compact and Lightweight Design: Requires less space compared to gate valves or ball valves.
• Quick Operation: Quarter-turn operation allows for fast opening and closing.
• Cost-Effective: Generally lower initial cost and maintenance cost.
• Versatile: Suitable for a wide range of applications including water, air, gases, and certain corrosive fluids.
• Good Flow Control: Provides reliable shut-off and regulating capabilities.
• Low Pressure Drop: When fully open, it creates minimal obstruction to flow.

Technical Specifications and Parameters

Our butterfly valves are engineered for superior performance and durability. Below are the detailed product parameters.

Material Specifications

Size and Pressure Ratings

Actuator Options

• Manual: Lever, Gear Operator
• Pneumatic: Double Acting, Spring Return
• Electric: On/Off, Modulating Control
• Hydraulic: For high-torque applications

Applications of Butterfly Valves

• Water and Wastewater Treatment Plants
• Chemical and Petrochemical Industries
• HVAC Systems (Heating, Ventilation, and Air Conditioning)
• Power Generation
• Food and Beverage Processing
• Pharmaceutical Manufacturing
• Marine and Shipbuilding
• Pulp and Paper Industry
• Irrigation and Fire Protection Systems

Butterfly Valve FAQs

What is the main function of a butterfly valve?

The primary function of a butterfly valve is to isolate or regulate the flow of a fluid within a piping system. It operates by rotating a disc a quarter turn (90 degrees) to either allow full flow, block flow completely, or position itself at any intermediate point for throttling purposes.

What are the different types of butterfly valves?

There are several types of butterfly valves, primarily categorized by their design and seating arrangement. The main types are: Wafer Type (which is clamped between two pipe flanges), Lug Type (which has threaded inserts allowing it to be bolted directly to one flange, useful for end-of-line service), and Double Flanged Type. They are also classified by seat type: Resilient Seated (with a soft seat like EPDM or PTFE for tight shut-off) and Metal Seated (for high temperatures or abrasive services).

How do I select the right seat material for my butterfly valve?

Selecting the correct seat material is critical and depends on the fluid's chemical composition, temperature, pressure, and required sealing performance. EPDM is common for water and mild chemicals up to 120°C. NBR is suitable for oils and fuels. Viton (FKM) offers excellent resistance to high temperatures (up to 150°C) and a wide range of chemicals, including hydrocarbons. PTFE is ideal for highly corrosive fluids and offers a very low coefficient of friction. Always consult chemical compatibility charts and pressure-temperature ratings.

What is the difference between a butterfly valve and a ball valve?

While both are quarter-turn valves, they have distinct differences. A butterfly valve uses a thin disc that rotates around a central stem, making it more compact and lighter, especially in larger sizes. A ball valve uses a perforated ball that rotates. Butterfly valves generally have a lower pressure rating and can be more prone to cavitation in throttling services but are more cost-effective for large diameters. Ball valves typically offer a tighter seal (bubble-tight) and better full-bore flow but are bulkier and more expensive in larger sizes.

Can a butterfly valve be used for throttling?

Yes, butterfly valves can be used for throttling or flow control. However, it is important to select the right type of valve and disc design. The characteristic curve of a butterfly valve is not perfectly linear, and cavitation can occur if the valve is operated at very low opening angles with high pressure drops. For precise modulating control, a characterized disc or a specific V-port disc design is recommended to achieve a more linear flow characteristic.

What maintenance does a butterfly valve require?

Butterfly valves are known for their low maintenance. Routine maintenance typically involves periodic inspection for external leaks, checking the operation of the actuator, and ensuring the stem and disc can move freely without binding. For resilient-seated valves, the seat may eventually wear and need replacement after many cycles or exposure to abrasive media. Lubrication of the stem bearings and seals might be necessary depending on the design and service conditions. Always follow the manufacturer's specific maintenance guidelines.

What standards do butterfly valves comply with?

Butterfly valves are manufactured to various international standards to ensure quality, safety, and interoperability. Common standards include API 609 for design and testing, MSS SP-67 and MSS SP-68 for dimensions and face-to-face lengths, ISO 5752 for basic series, and AWWA C504 for waterworks applications. Material standards like ASTM specify the grades of iron, steel, and other alloys used. Certifications like ISO 9001 for quality management are also common among reputable manufacturers.

How do I install a wafer-style butterfly valve correctly?

Installing a wafer-style butterfly valve requires careful alignment. First, ensure the pipe flanges are clean, aligned, and parallel. Insert the valve between the flanges, making sure the disc is in the partially open position (around 10-15 degrees) to avoid damaging the seat during insertion. Align the bolt holes. Insert the bolts and washers, and hand-tighten the nuts evenly in a cross-pattern. Finally, torque the nuts to the manufacturer's specified value in multiple passes using the cross-pattern method to ensure a uniform, leak-free seal. Do not use the valve to draw the pipes together.