What types of butterfly valves are available?
There are four main types, distinguished by the position of the disc relative to the seat:
| Type |
Application |
Advantage |
Disadvantage |
| Concentric |
Daily use, water, air |
+ Lowest purchase price |
- Rubber wears with prolonged open or closed position |
| Double eccentric |
Infrequent operation, higher pressure |
+ Less wear, lower torque |
- Higher price than concentric |
| Triple eccentric |
Demanding applications, high pressure/temperature |
+ Metal-to-metal seal, zero leakage |
- Higher purchase price |
| Quadruple eccentric |
Extreme conditions |
+ Maximum service life |
- Limited range, higher cost |
Concentric butterfly valve
The concentric butterfly valve is the most common type for daily operation. The disc is mounted exactly in the centre of the body and presses against a rubber liner when closed. A drawback is that prolonged open position can deform the rubber, potentially causing leakage when the valve is closed again. After prolonged closed position, a higher breakaway torque is required. Choose this type when the valve is operated regularly and the medium is not aggressive.
Double and triple eccentric butterfly valve
In a double eccentric butterfly valve, the disc is offset slightly from the centre of the body, meaning it makes minimal contact with the seat during opening and closing. This significantly extends service life and reduces the required torque. Choose this type when the valve is operated infrequently or at higher pressures.
Triple eccentric butterfly valves are used in demanding applications such as high pressure, high temperature or aggressive media. The disc only contacts the seat at the very last moment — metal to metal — resulting in a virtually leak-free closure. This type is also referred to as a High Performance butterfly valve.
Fire-safe butterfly valve
For applications where fire safety is a requirement — such as in the process industry, offshore or buildings with elevated fire risks — a fire-safe butterfly valve is required. This version is certified to API 607 or API 609 and ensures the valve retains its sealing function in the event of a fire. Ebora supplies fire-safe butterfly valves on request, including as an ATEX version. Ask for available certificates when placing your enquiry.
Butterfly valve 125mm and other sizes
Butterfly valves are available in a wide size range, from DN40 to DN2000. A frequently requested size is the 125mm butterfly valve (DN125), widely used in water pipelines, cooling water systems and HVAC applications. When selecting the right size, consider:
- Nominal diameter (DN) of the pipeline
- Allowable working pressure (PN)
- Medium and temperature
- Flange standard (EN 1092, ANSI/ASME)
Connection types
Ebora supplies butterfly valves with various connection types:
- Wafer — clamped between two flanges, compact and lightweight
- Lug type — fitted with threaded inserts, also suitable as an end valve
- Mono flange — flanged on one side
- Double flange — flanged on both sides, for higher pressures
Select the connection type based on the flange standard in your installation and the required pressure class.
Pneumatic butterfly valve
A pneumatic butterfly valve is used when automated operation is required and compressed air is available. Rack & pinion and scotch yoke quarter-turn actuators are the most commonly used drive principles. Choose from:
- Spring return (fail-safe): the actuator opens via air pressure; the spring closes the valve upon loss of compressed air
- Double acting: air opens and closes the valve — suitable when a forced end position upon failure is not desired
Pneumatic butterfly valves are supplied fully assembled and tested. Available on request with solenoid valve, end position signalling or positioner.
Electrically operated butterfly valve
Electric actuators are suitable when no compressed air is available or when the signal from a PLC needs to be processed directly. The actuator opens and closes the butterfly valve via an electric motor. For modulating applications, an electric actuator with positioner is available, controlled via a 4-20 mA signal.
Please note: an electrically operated butterfly valve is not a suitable replacement for a control valve in applications requiring precise flow regulation.
Butterfly valve applications
Butterfly valves are used across a wide range of industries:
- Marine and offshore
- Heating, ventilation and air conditioning (HVAC)
- Chemical and petrochemical industry
- Drinking water and sewage systems
- Equipment and machine building
- Food and pharmaceutical industry
Materials
Material selection depends on the medium, temperature and chemical resistance required. Ebora supplies butterfly valves in, among others:
- Cast iron (GG25) — standard for water and air
- Ductile iron (GGG40) — higher pressures and impact resistance
- Stainless steel (SS 316) — corrosive media
- Bronze — drinking water and marine applications
- PVC-U, PVC-C, PP, PVDF — chemically aggressive media
Butterfly valve brands
In addition to the standard range, Ebora also supplies butterfly valves from specialist manufacturers including Wouter Witzel, Bray, Emerson, Keystone, FIP and Georg Fischer.
Select the right butterfly valve based on medium, pressure and diameter, or request a quote directly from our specialists.
Frequently asked questions
What is the difference between a wafer and a lug type butterfly valve?
A wafer butterfly valve is clamped between two flanges and is not suitable as an end valve. A lug type butterfly valve has threaded inserts in the body, allowing the valve to be bolted independently on both sides — also usable as an end valve when one side of the pipeline needs to remain depressurised.
When should I choose a fire-safe butterfly valve?
A fire-safe butterfly valve is required when the installation falls under fire safety regulations, such as in the offshore industry, refineries or buildings with elevated fire risk. Choose a version certified to API 607 or API 609. Ask for the available certificates when placing your enquiry.
Can a butterfly valve be used as a control valve?
A butterfly valve can be used for basic flow control, but is not a full replacement for a control valve. For precise regulation — for example where a specific Cv curve or low pressure drop is required — a control valve is the better choice. Contact us for advice based on your process data.
Which butterfly valve is suitable for aggressive media?
Choose a butterfly valve with a body and disc in SS 316 or plastic (PVC-C, PP or PVDF) and a seat in EPDM, PTFE or FKM (Viton), depending on the specific medium and temperature. Our specialists will advise you on the right material combination.
