China Valve Manufacturer
  • Home
  • Company
    • Breif Introduction
    • Organization Structure
    • Corporate Culture
    • Sales Achievement
  • Products
    • Ball Valve >
      • Cast Steel Floating Ball Valve
      • Forged Steel Floating Ball Valve
      • Cast Steel Trunnion Ball Valve
      • Forged Steel Trunnion Ball Valve
      • Fully Welded Ball Valve
      • Top Entry Ball Valve
    • Gate Valve >
      • Cast Steel Gate Valve
      • Pressure Seal Gate Valve
      • Through Conduit Gate Valve
      • Forged Steel Gate Valve
    • Globe Valve >
      • Cast Steel Globe Valve
      • Pressure Seal Globe Valve
      • Forged Steel Globe Valve
    • Check Valve >
      • Swing Check Valve
      • Pressure Seal Check Valve
      • Dual Plate Check Valve
      • Forged Steel Check Valve
    • Butterfly Valve >
      • Concentric Type Butterfly Valve
      • Double Eccentric Butterfly Valve
      • Triple Offset Butterfly Valve >
        • Wafer Triple Offset Butterfly Valve
        • Lug Type Triple Offset Butterfly Valve
        • Flange Triple Offset Butterfly Valve
      • High Performance Butterfly Valve
      • AWWA C504 Butterfly Valve
      • Electric Butterfly Valve
      • Pneumatic Butterfly Valve
      • High Pressure Butterfly Valve
      • Bi-directional Butterfly Valve
    • Plug Valve >
      • Sleeve Soft Sealing Plug Valve
      • Inverted Pressure Balance Lubricated Plug Valve
    • Steel Strainer
  • Quality Control
    • Quality Procedure
    • Products Showroom
    • Technical R&D
    • Commitment
  • Service Online
    • Catalog Download
    • Drawing Download
    • FAQ & Feedback
    • Sitemap
  • Valve Blog
  • Contact Us
    • Friend Link

What is a butterfly valve?

6/11/2012

0 Comments

 
A butterfly valve is a valve which can be used for isolating or regulating flow. The closing mechanism takes the form of a disk. Operation is similar to that of a ball valve, which allows for quick shut off. Butterfly valves are generally favored because they are lower in cost to other valve designs as well as being lighter in weight, meaning less support is required. The disc is positioned in the center of the pipe, passing through the disc is a rod connected to an actuator on the outside of the valve. Rotating the actuator turns the disc either parallel or perpendicular to the flow. Unlike a ball valve, the disc is always present within the flow, therefore a pressure drop is always induced in the flow, regardless of valve position.


A butterfly valve is from a family of valves called quarter-turn valves. The "butterfly" is a metal disc mounted on a rod. 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.


There are different kinds of butterfly valves, each adapted for different pressures and different usage. The resilient butterfly valve, which uses the flexibility of rubber, has the lowest pressure rating. The high performance butterfly valve, used in slightly higher-pressure systems, features a slight offset in the way the disc is positioned, which increases the valve's sealing ability and decreases its tendency to wear. The valve best suited for high-pressure systems is the triple offset butterfly valve, which makes use of a metal seat,[clarification needed] and is therefore able to withstand a greater amount of pressure.

1. Structure
Butterfly valves are valves with a circular body and a rotary motion disk closure member which is pivotally supported by its stem. A butterfly valve can appear in various styles, including eccentric and high-performance valves. These are normally a type of valve that uses a flat plate to control the flow of water. As well as this, butterfly valves are used on firefighting apparatus and typically are used on larger lines, such as front and rear suction ports and tank to pump lines.


2. Types
Concentric butterfly valves - This type of valves has a resilient rubber seat with a metal disc.
Doubly-eccentric butterfly valves (high-performance butterfly valves or double-offset butterfly valves) - Different type of materials is used for seat and disc. Triply-eccentric butterfly valves (triple-offset butterfly valve) - The seats are either laminated or solid metal seat design.


3. Triply-eccentric (offset) design
Triple eccentric (offset) Design prevents galling and scratches between the metal seat and the metal disc due to its unique design. The only time where the seal comes into contact with the seat is at the point of complete closure. Triple offset valves are generally used in applications which require bi-directional tight shut-off in oil and gas, LNG/NPG terminal and tanks, chemical factories, and shipbuilding. Widely use for dirty/heavy oil to prevent extrusion.


4. Wafer-style butterfly valves
The wafer style butterfly valve is designed to maintain a seal against bi-directional pressure differential to prevent backflow in systems designed for unidirectional flow. It accomplishes this with a tightly fitting seal; i.e., gasket, o-ring, precision machined, and a flat valve face on the upstream and downstream sides of the valve.


5. Lug-style butterfly valve
Lug-style valves have threaded inserts at both sides of the valve body. This allows them to be installed into a system using two sets of bolts and no nuts. The valve is installed between two flanges using a separate set of bolts for each flange. This setup permits either side of the piping system to be disconnected without disturbing the other side.
A lug-style butterfly valve used in dead end service generally has a reduced pressure rating. For example a lug-style butterfly valve mounted between two flanges has a 150 psi pressure rating. The same valve mounted with one flange, in dead end service, has a 75 psi rating.

0 Comments



Leave a Reply.

    Author

    welcovalve@gmail.com
    China Valve Manufacturer

    Archives

    April 2019
    July 2012
    June 2012
    February 2012
    January 2012
    December 2011
    December 2010

    Categories

    All
    Accessories
    Api 598
    Ball Valve
    Butterfly Valve
    China Valve
    Chinese Valve
    Cryogenic Valve
    Electric Valve
    Industrial Valves
    Valve Blog
    Valve Drawing
    Valve Fitting
    Valve Industry
    Valve Information
    Valve Inspection And Testing
    Valve Market
    Valve Material
    Valve Pressure
    Valve Screw
    Valve Size
    Valve Standards
    Valve Trim
    Valve Type

    RSS Feed

Powered by Create your own unique website with customizable templates.