characteristics of the Butterfly Valve
A butterfly valve is a type of valve that uses a disc shaped like a butterfly to regulate the flow of fluids in a pipeline. The disc is located in the center of the flow and rotates on an axis perpendicular to the direction of the flow. By rotating the disc, the valve’s opening and closing can be controlled, allowing for quick and efficient flow regulation. Butterfly valves are widely used in various industries for flow control in liquid and gas lines.
Butterfly valves are designed with different sealing systems; centered seal, single ec centric seal, double ec centric seal, triple ec centric seal, and variable ec centric seal. The sealing principles of these structures are here down explained.
Sealing load is produced between the sealing faces or seat and disc under certain magnitude of interference, to make the valve tight. Lined with rubber on body, this design is applicable form medium and small size valves. Due to the deformation, during opening and closing, disc is always under extrusion. So the upper and lower shafts are heavily stressed, which may result on a poor service life. Moreover this stress implies torque at the beginning of the opening and closing being very relatively high. These not desirable facts cause scratches on the seal surfaces, high resistant torque, and abrasion on the rubber.
SINGLE ECCENTRIC VALVE
The rotation center of disc (namely center of valve shaft), and the sealing section of disc form up an ‘a’ ec centric. . This makes disc sealing face gradually separated from the seat sealing surface while opening and closing. Once the valve has been completely opened, there will appear a gap between the sealing surfaces, which will make the stress on the seat, disc and shaft be much lower than centered seal valves.
DOUBLE ECCENTRIC VALVE
There is a second ‘b’ ec centricity between the center of the body and the rotation center of disc. This valves may be used for metal to metal seat, so they are suitable for high temperature service. But as the tightness is made by elastic deformation of sealing surface, combination of pressure and temperature have a big influence, so the performance of valve with high pressure, or temperature is not so good.
TRIPLE ECCENTRIC VALVE
Based on double ec centric valve design, an angle is formed between the centre of the seat and the centre of the body. . This third ec centricity makes sealing surfaces immediately separated from each other.
ARFLU MANUFACTURING RANGE
ARFLU, is known for the extensive manufacturing range, we manufacture large number of valves in almost all sizes and materials. If you do not find the valve you need in the box attached, please contact our sales representatives and we will study the feasibility of producing in other dimensions.
INTERNATIONAL DESIGN STANDARDS
DESIGN AND MANUFACTURE:
API 599 Metal Plug Valves – Flanged, Threaded and Welding Ends.
API-6D ISO 14313:1999, petroleum and natural gas industries-pipeline transportation systems-pipeline valves.
INSPECTION AND TEST:
API 598: API 598 valve inspection and testing.
ASME B16.5 pipe flanges and flanged fittings
ASME B16.25 buttwelding ends
FACE TO FACE AND END TO END:
ASME B16.10 face to face and end-to-end dimensions of valves
* Other standards/materials upon request