What are the different types of butterfly valves?

Butterfly valves are commonly classified by disc design, connection type, seat material, body material and operation method. The main types include concentric, single offset, double offset and triple offset butterfly valves. In real projects, buyers often compare wafer butterfly valves, lug butterfly valves, flanged butterfly valves, grooved butterfly valves, gear operated butterfly valves and UL/FM fire protection butterfly valves before selecting the final specification.

For most water supply, HVAC and general industrial systems, a soft-seated concentric butterfly valve is often enough. For fire protection systems, a listed or approved fire protection butterfly valve is usually required. For higher pressure, higher temperature or more demanding shut-off service, double offset, triple offset or metal-seated butterfly valves may be more suitable.

Key Takeaways

• Choose a wafer butterfly valve when you need a compact and economical valve installed between two pipe flanges.

• Choose a lug butterfly valve when one side of the pipeline may need to be removed for maintenance.

• Choose a flanged butterfly valve for larger sizes, stronger pipe support or projects requiring flanged-end installation.

• Choose a grooved butterfly valve for fire protection, sprinkler and grooved piping systems.

• Choose a gear operated butterfly valve for larger valves or applications where lever operation requires too much force.

• Choose a UL/FM butterfly valve for fire protection projects where UL Listed or FM Approved products are required.

• PN16 and Class 150 should not be treated as direct equivalents. Always confirm flange standard, pressure-temperature rating and bolt hole dimensions.

• For seat materials, EPDM is widely used for water, NBR is better for oils, and PTFE is commonly considered for chemical media after compatibility confirmation.

• For body materials, ductile iron is widely used for water and fire systems, cast iron is economical for low-pressure services, and stainless steel is preferred for corrosive or hygienic applications.

Main Types of Butterfly Valves by Disc Design

Concentric Butterfly Valve

A concentric butterfly valve, also called a zero-offset butterfly valve, has the stem located in the center of the disc and the pipeline. The disc rotates against a resilient seat, usually made from EPDM, NBR or another elastomer depending on the medium.

This is the most common butterfly valve design for water supply, HVAC, irrigation, fire protection water lines and general low-pressure systems. It is simple, lightweight, cost-effective and easy to install.

Best for:

• Water supply systems

• HVAC pipelines

• Fire protection water lines

• Irrigation systems

• General low-pressure industrial service

Limitations:

Because the disc remains in contact with the seat during opening and closing, seat wear may occur faster than in offset designs, especially in high-cycle or abrasive applications.

Single Offset Butterfly Valve

A single offset butterfly valve has the shaft slightly offset from the centerline of the disc. This reduces friction between the disc and seat during operation.

Compared with a concentric butterfly valve, a single offset design can offer smoother operation and longer seat life. It is suitable for moderate service conditions where better sealing and lower operating torque are needed.

Double Offset Butterfly Valve

A double offset butterfly valve has two offsets: one from the centerline of the pipe and another from the centerline of the sealing surface. This allows the disc to move away from the seat more quickly during opening, reducing friction and wear.

Double offset butterfly valves are often used in higher pressure or higher temperature services than standard soft-seated concentric valves.

Best for:

• Industrial water systems

• Oil and gas pipelines

• Steam or hot water systems

• Higher pressure shut-off applications

Triple Offset Butterfly Valve

A triple offset butterfly valve adds a third offset in the sealing geometry. The sealing surface is usually conical, allowing the disc and seat to contact only at the final closing point.

This design reduces friction, improves sealing performance and is suitable for demanding applications such as high temperature, high pressure, steam, oil and gas, chemical processing and critical shut-off service.

Best for:

• High-temperature pipelines

• High-pressure service

• Steam systems

• Oil and gas applications

• Severe industrial service

• Metal-seated shut-off applications

Butterfly Valve Types by Connection

Connection type is one of the most important selection factors because it determines how the valve is installed, maintained and matched with the pipe system.

Wafer Butterfly Valve

A wafer butterfly valve is installed between two pipe flanges using long bolts or studs. It has a slim body and is one of the most economical butterfly valve types.

Wafer butterfly valves are widely used in water treatment, HVAC, cooling water, compressed air and general industrial pipelines. They are compact and lightweight, making them suitable for projects where installation space and cost are important.

Choose a wafer butterfly valve when:

• The valve is installed between two flanges.

• The system does not require end-of-line service.

• You want a compact and cost-effective solution.

• The pipeline can support both sides of the valve during maintenance.

Typical applications:

• HVAC systems

• Water treatment plants

• Cooling water pipelines

• General industrial water systems

• Low to medium pressure service

Lug Butterfly Valve

A lug butterfly valve has threaded lugs around the valve body. It can be installed between two flanges with separate bolts from each side.

The key advantage of a lug butterfly valve is that one side of the pipeline can often be disconnected while the other side remains connected, depending on the system design and pressure conditions. This makes lug butterfly valves more convenient for maintenance than wafer butterfly valves.

Choose a lug butterfly valve when:

• One side of the pipeline may need to be removed.

• The valve may be used near the end of a pipeline.

• Maintenance access is important.

• A stronger bolted connection is required than wafer type.

Typical applications:

• Water distribution systems

• Pump stations

• Industrial process pipelines

• Maintenance-sensitive installations

Wafer vs Lug Butterfly Valve: Which One Should You Choose?

For most standard water or HVAC pipelines, a wafer butterfly valve is enough. If the system requires easier disassembly or possible end-of-line service, a lug butterfly valve is usually the better option.

Flanged Butterfly Valve

A flanged butterfly valve has flanges cast or mounted on both ends of the valve body. It connects directly to pipe flanges with bolts.

Flanged butterfly valves are commonly used in larger pipelines, municipal water systems, industrial plants and applications requiring a more rigid connection. They are heavier than wafer and lug valves but provide strong installation stability.

Choose a flanged butterfly valve when:

• The pipeline uses flanged-end connections.

• Larger valve sizes are required.

• The project needs stronger pipe support.

• The specification calls for flanged valves.

Typical applications:

• Municipal water supply

• Wastewater treatment

• Industrial pipeline systems

• Pump stations

• Large-diameter pipelines

Grooved Butterfly Valve

A grooved butterfly valve is designed for grooved piping systems and is installed with grooved couplings. It is especially common in fire protection and sprinkler systems.

Grooved butterfly valves offer fast installation, easy maintenance and good compatibility with grooved pipe networks. In fire protection projects, grooved butterfly valves are often supplied with supervisory or tamper switches to indicate valve open or closed status.

For sprinkler systems requiring valve position monitoring, a grooved butterfly valve with tamper switch can help the system monitor valve status and improve operational safety.

Choose a grooved butterfly valve when:

• The pipeline uses grooved couplings.

• The project is a fire protection or sprinkler system.

• Fast installation is required.

• The valve needs open/close signal monitoring.

Typical applications:

• Fire sprinkler systems

• Fire protection water pipelines

• Pump rooms

• Commercial buildings

• Industrial fire protection networks

Butterfly Valve Types by Operation Method

Manual Lever Butterfly Valve

A manual lever butterfly valve is operated by a handle. It is suitable for small sizes and low-torque applications.

Best for:

• Small pipelines

• Simple open/close service

• Low-pressure water systems

• Applications without automation requirements

Gear Operated Butterfly Valve

A gear operated butterfly valve, also called a worm gear butterfly valve, uses a gearbox to reduce operating torque. The operator turns a handwheel, and the gearbox slowly rotates the valve disc.

Gear operation is especially useful for larger valves, higher pressure pipelines or systems where direct lever operation would be difficult. It is also common in fire protection systems where clear and controlled valve operation is required.

Choose a gear operated butterfly valve when:

• The valve size is large.

• Manual operation requires too much force.

• Slow and controlled opening or closing is needed.

• The valve is installed in a fire protection or building water system.

Typical applications:

• Fire protection systems

• Water supply pipelines

• Pump rooms

• Industrial water systems

• Large-diameter HVAC pipelines

Electric Butterfly Valve

An electric butterfly valve uses an electric actuator for remote or automatic control. It is suitable for systems connected to PLC, building management systems or automated production lines.

Best for:

• Remote operation

• Automated flow control

• Water treatment systems

• Chemical processing

• HVAC automation

Pneumatic Butterfly Valve

A pneumatic butterfly valve uses compressed air to operate the valve. It offers fast opening and closing and is often used in automated industrial systems.

Best for:

• High-cycle operation

• Fast shut-off

• Industrial automation

• Hazardous areas where electric actuators may not be preferred

Hydraulic Butterfly Valve

A hydraulic butterfly valve is used where high torque is required, especially for large-diameter or high-pressure systems.

Best for:

• Large-size valves

• High-pressure pipelines

• Heavy-duty industrial systems

• Applications requiring high operating torque

Fire Protection Butterfly Valve

A fire protection butterfly valve is used in fire sprinkler and fire water supply systems to control water flow. Unlike general industrial butterfly valves, fire protection valves often need to meet specific project approvals, such as UL Listed or FM Approved requirements.

In fire protection systems, the valve is commonly required to provide a clear open or closed indication. Some fire protection butterfly valves are equipped with supervisory switches or signal gearboxes so the fire alarm system can monitor valve position.

Common fire protection butterfly valve types include:

• Wafer fire protection butterfly valve

• Grooved fire protection butterfly valve

• Gear operated fire protection butterfly valve

• UL/FM butterfly valve

• Ductile iron butterfly valve for fire systems

Which Butterfly Valve Is Used for Fire Protection Systems?

For fire protection systems, the most common choices are grooved butterfly valves and wafer butterfly valves with supervisory switches. Grooved butterfly valves are widely used in sprinkler pipelines because they match grooved pipe connections and allow quick installation. Wafer butterfly valves are also used where the pipeline uses flanged connections.

If the project specification requires certification, choose a UL/FM butterfly valve or a fire protection valve that matches the required listing scope rather than a general-purpose valve.

UL/FM Butterfly Valve

A UL/FM butterfly valve is designed for fire protection service and supplied according to UL Listed or FM Approved requirements when required by the project. These valves are commonly used in fire sprinkler systems, pump rooms, hydrant systems and building fire water pipelines.

When selecting a UL/FM butterfly valve, always confirm the exact model, size, pressure rating and listing scope before using the valve in a fire protection project. Approval requirements may vary by valve type, connection end, size range and working pressure.

Before ordering, confirm:

• Certification requirement: UL, FM, CUL or other project approval

• Valve type: wafer, grooved or other specified body type

• Size: for example 2”, 2.5”, 3”, 4”, 6”, 8”, 10” or 12”

• Working pressure: such as 175 psi, 200 psi, 250 psi, 300 psi or other model-specific rating

• Supervisory switch or tamper switch requirement

• Connection standard

• Body material

• Seat material

Do not replace a certified fire protection butterfly valve with a general-purpose industrial valve unless the project engineer or authority having jurisdiction confirms it is acceptable.

Butterfly Valve Types by Seat Material

The seat material affects sealing performance, temperature range, chemical compatibility and service life. Common butterfly valve seat options include EPDM, NBR and PTFE. Available seat materials should always be confirmed according to the medium, temperature, pressure, valve structure and project specification.

EPDM Seat Butterfly Valve

EPDM is one of the most common seat materials for water systems. It has good resistance to water, steam, weak acids and alkalis.

Best for:

• Water supply

• Fire protection water

• HVAC

• Cooling water

• Wastewater

• General non-oil service

Avoid using EPDM for:

• Oil

• Petroleum-based media

• Hydrocarbon service

NBR Seat Butterfly Valve

NBR, also called nitrile rubber, has better resistance to oils than EPDM. It is commonly used where the medium contains oil, fuel or petroleum-based fluids.

Best for:

• Oil-containing media

• Fuel systems

• Compressed air with oil mist

• Some industrial fluid systems

Avoid using NBR for:

• Strong oxidizing media

• High-temperature steam

• Applications requiring strong weather or ozone resistance

PTFE Seat Butterfly Valve

PTFE has strong chemical resistance and is commonly considered for many corrosive media. It may be suitable for chemical processing and applications where rubber seats are not compatible.

However, PTFE availability depends on the valve structure, size, pressure class and supplier configuration. Before selecting PTFE, confirm the exact medium, concentration, temperature and pressure conditions.

Best for:

• Chemical media

• Corrosive fluids

• Acids and alkalis

• Applications requiring higher chemical resistance

Limitations:

PTFE seats are usually more expensive than EPDM or NBR. The valve structure, pressure rating and temperature range should be confirmed before selection.

EPDM vs NBR vs PTFE: How to Choose

For most water and fire protection projects, EPDM is the standard choice. For oil media, choose NBR. For chemical pipelines, consider PTFE only after confirming the exact medium, concentration, pressure and temperature.

Butterfly Valve Types by Body Material

Cast Iron Butterfly Valve

Cast iron butterfly valves are economical and suitable for low-pressure water and general utility service. They are often used where cost is the main concern and the working conditions are not demanding.

Best for:

• Low-pressure water systems

• HVAC

• General building services

• Non-critical pipelines

Ductile Iron Butterfly Valve

A ductile iron butterfly valve offers better strength and toughness than standard cast iron. It is widely used in water supply, wastewater, fire protection and industrial pipeline systems.

For fire protection and water supply projects, ductile iron is usually preferred because it offers better strength and toughness than standard cast iron while remaining more economical than stainless steel.

Best for:

• Fire protection systems

• Water distribution

• Wastewater treatment

• Pump stations

• Building water pipelines

• Grooved butterfly valves

• Wafer and lug butterfly valves for general service

Stainless Steel Butterfly Valve

Stainless steel butterfly valves are used where corrosion resistance, hygiene or chemical compatibility is important. They are more expensive than cast iron or ductile iron valves but provide better resistance in corrosive environments.

Best for:

• Chemical processing

• Food and beverage

• Pharmaceutical systems

• Seawater or corrosive environments

• Hygienic pipelines

Cast Iron vs Ductile Iron vs Stainless Steel

For most water and fire protection projects, ductile iron is usually the most practical option. For low-budget, low-pressure systems, cast iron may be enough. For corrosive or hygienic service, stainless steel is the better choice.

PN16 vs Class 150: How to Choose the Right Pressure Rating

Pressure rating is one of the most common sources of confusion when selecting butterfly valves. PN16 and Class 150 should not be treated as direct equivalents. The correct choice depends on the flange standard, pressure-temperature rating, bolt hole dimensions and project specification.

What Does PN16 Mean?

PN16 means the valve is designed for a nominal pressure of 16 bar, equal to 1.6 MPa under standard reference conditions. PN-rated valves are commonly used with EN, DIN, BS or ISO flange systems.

PN16 butterfly valves are widely used in water supply, HVAC, fire protection and general industrial pipelines.

What Does Class 150 Mean?

Class 150 is an ASME pressure class. It does not simply mean 150 psi. The allowable pressure depends on valve material and working temperature. In many projects, buyers use “ANSI Class 150” to describe the flange standard, but the actual flange drilling and valve design must still be confirmed.

PN16 vs Class 150 Selection Guide

The safest approach is not to choose only by “PN16” or “Class 150”. Always confirm the pipe flange standard, working pressure, test pressure, temperature, medium and bolt hole dimensions before placing an order.

How to Choose the Right Butterfly Valve

Use the following selection process before requesting a quotation.

1. Confirm the Application

2. Confirm the Connection Type

• Use a wafer butterfly valve for compact flanged installation.

• Use a lug butterfly valve when easier maintenance is required.

• Use a flanged butterfly valve for rigid flanged pipe systems.

• Use a grooved butterfly valve for grooved fire protection or sprinkler pipelines.

3. Confirm the Seat Material

• Use EPDM for water, HVAC and fire protection water.

• Use NBR for oil or petroleum-based media.

• Consider PTFE for chemical or corrosive media only after confirming compatibility.

4. Confirm the Body Material

• Use cast iron for economical low-pressure systems.

• Use ductile iron for fire protection, water supply and wastewater.

• Use stainless steel for corrosive, hygienic or chemical applications.

5. Confirm the Operation Method

• Use lever operation for small sizes.

• Use gear operation for larger sizes or fire protection systems.

• Use electric actuator for remote automatic control.

• Use pneumatic actuator for fast automated operation.

• Use hydraulic actuator for high-torque large valves.

What Information Should You Provide for a Butterfly Valve Quote?

To receive an accurate quotation, provide the following details:

1. Valve type: wafer butterfly valve, lug butterfly valve, flanged butterfly valve, grooved butterfly valve, gear operated butterfly valve or fire protection butterfly valve.

2. Size: DN size or inch size, such as DN50, DN100, DN150, 2”, 4”, 6” or 8”.

3. Pressure rating: PN10, PN16, Class 125, Class 150, 175 psi, 200 psi, 250 psi, 300 psi or other project requirement.

4. Connection standard: EN, DIN, BS, ISO, JIS, ANSI, ASME, AWWA or grooved standard.

5. Body material: cast iron, ductile iron, stainless steel, carbon steel or other required material.

6. Seat material: EPDM, NBR, PTFE or metal seat, depending on actual compatibility.

7. Disc and stem material: ductile iron, stainless steel, aluminum bronze or other project-specified material.

8. Medium: water, wastewater, fire water, oil, gas, chemical liquid, powder or slurry.

9. Working temperature: normal temperature, hot water, steam or high-temperature service.

10. Operation method: lever, gear operator, electric actuator, pneumatic actuator or hydraulic actuator.

11. Certification requirement: UL, FM, CUL, NSF, CE, WRAS, ISO or other project approvals.

12. Quantity and delivery requirement: required quantity, destination country, packaging requirement and delivery time.

Providing these details helps the supplier recommend the correct valve and avoid mismatched flange drilling, seat material failure, incorrect pressure rating or unsuitable certification.

Maitolead Butterfly Valve Solutions

Maitolead supplies butterfly valves for fire protection, water treatment, HVAC, industrial pipelines and general fluid control systems. Available options may include:

• Wafer butterfly valve

• Lug butterfly valve

• Flanged butterfly valve

• Grooved butterfly valve

• Gear operated butterfly valve

• Fire protection butterfly valve

• Ductile iron butterfly valve

• UL/FM butterfly valve

• EPDM and NBR seated butterfly valves

• Manual, gear operated, electric and pneumatic butterfly valves

Common seat options in the market include EPDM, NBR and PTFE. For Maitolead butterfly valve configurations, please confirm the available seat material based on the required medium, temperature and project specification.

Need help choosing a butterfly valve? Send us your valve size, pressure rating, connection standard, medium, seat material and certification requirement. Maitolead can help recommend a suitable wafer, lug, flanged, grooved or fire protection butterfly valve for your project.

FAQ

What is the difference between a wafer butterfly valve and a lug butterfly valve?

A wafer butterfly valve is clamped between two pipe flanges and is usually more compact and economical. A lug butterfly valve has threaded lugs and is better when one side of the pipeline may need to be removed for maintenance.

Which butterfly valve is best for fire protection systems?

For fire protection systems, grooved butterfly valves and wafer butterfly valves with supervisory switches are commonly used. If the project requires approval, choose a UL/FM butterfly valve and confirm the exact listing scope.

Can I use a general butterfly valve for a fire sprinkler system?

Not always. Fire sprinkler systems may require UL Listed or FM Approved valves. Always check the project specification and local fire protection requirements before using a general-purpose valve.

How do I choose between PN16 and Class 150?

Choose PN16 for EN, DIN, BS or ISO flange systems. Choose Class 150 when the project uses ASME or ANSI flange standards. PN16 and Class 150 are not direct equivalents, so always confirm flange drilling, working pressure and temperature before ordering.

Which seat material is better: EPDM, NBR or PTFE?

EPDM is suitable for water and fire protection systems. NBR is better for oil-containing media. PTFE is suitable for many chemical and corrosive fluids, but compatibility must be confirmed based on medium, concentration, temperature and valve design.

Is ductile iron better than cast iron for butterfly valves?

Ductile iron has better strength and toughness than cast iron, making it a common choice for water supply, wastewater and fire protection systems. Cast iron is more economical for low-pressure general service.

What details are needed for a butterfly valve quotation?

You should provide valve type, size, pressure rating, connection standard, body material, seat material, medium, temperature, operation method, certification requirement and quantity.