Butterfly valves comply with API 609/AWWA C-504 standard. This type of valve with soft rubber seats is used in the water treatment industries valves can be used for throttling as well as open/close applications. The main features are a leak proof hermetic seal, easy installation and operation at the maximum differential pressure, Valves can be offered in concentric, Double & triple offset design based on the customer requirement ( Zero leakage triple offset designs).
• Uninterrupted seal along the 360° of the disc.
• Wafer, Lug or Slotted ends style.
• Manual operation by lever, gear operator or automated.
• Other interiors available at the request of the client.
• Soft seals can be EPDM, neoprene or NBR.
• Pressure tests according to API-598.
Advantages and Features of Butterfly Valves
The butterfly valve derives its name from the wing-like action of the disc which operates at right angles to the flow. Its main advantage is a seating surface which is not critical. It is designed for flow isolation. The disc impinges against a resilient liner to provide bubble tightness with low operating torque. Compact and with a simple construction, butterfly valves facilitate easy pipe arrangement. Due to disc, they have slightly reduced flow characteristics.
The valves are quick acting, good regulating characteristics, compact & light, low pressure isolation. Butterfly valves are simple, reliable and range in size from 40mm to 1000mm and beyond. They can be controlled by a notched lever, hand-wheel as well as by pneumatic or electric actuator. A shaft turns a disc 90º within a pipe. The disc angle within the pipe can provide a restriction varying from drip-tight through to almost full flow (except very small sizes).
Butterfly Valve Body Types
There are five main styles of butterfly valve body types, flanged, wafer, fully lugged, groove coupling, and hygienic.
Double flanged butterfly valves
Double flanged butterfly valves have a full flange at each side for ease of mounting in adjoining flanged pipework.
Wafer pattern where the butterfly valve sandwich mounts between flanges and securing bolts pass through both flanges to grip the valve between the flanges. The wafer body can have elongated lugs that assist with alignment, but these lugs are through-hole and are not threaded.
Fully lugged where the body has a full set of threaded lugs that perfectly match the mating flange, and the butterfly valve is secured by bolts from either side, screwed into the valve body.
Groove coupling bodies have an extended body in the form of a grooved pipe each side that mate with similarly grooved adjoining pipes, connected with a groove style coupling.
Hygienic butterfly valves have a variety of end connections that, apart from a butt welded version, allow fast disassembly and reassembly for wash-down purposes. These are typically a clamp style, or threaded union connection.
Operations of Butterfly Valve - Hand Operators and Actuators
Butterfly valves are either operated by hand making them manually operated, or by a valve actuator which makes them automatic.
- Hand operators are either a hand lever, or a hand-wheel operated gearbox.
- Actuators are either electric, pneumatic, or hydraulic.