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Thread: How & Why Are Butterfly Valves Used?

  1. #1
    Author Guest

    How & Why Are Butterfly Valves Used?

    How & Why Are Butterfly Valves Used?

    A Butterfly Valve is used to control the flow of material through a circular pipe or tube. Typically the material is air, gas, steam, or liquid. Certain dry materials may also be handled through a butterfly valve.

    Simply, a butterfly valve consists of a circular disc with its pivot axis at right angles to the direction material is flowing. The valve is made up of a body, seat, disc, stem, and actuator. Each component part is available in a variety of materials called “trim features.” Properly combining trim features to address material handled and environment is important in selecting the correct model valve for its intended service.

    Body
    A butterfly valve body can be made of cast iron, ductile iron, aluminum, carbon steel, stainless steel and exotic metals.

    Butterfly valves are available in wafer and lug style. Wafer style valves are installed “sandwiched” between pipe flanges. This style of valve is easier to replace or install. However, replacing a wafer valve requires the conveying line to be drained. Once the valve is removed, there is nothing to seal material either upstream or downstream from the removal point.

    Lug style valves contain tapped holes that allow them to be bolted directly to a mating flange. In the closed position, the valve independently seals material to the upstream and downstream side. Because of this independent sealing, lug valves may be used to isolate downstream equipment that may require replacement or maintenance.

    Seat
    Resilient seated valves are the most commonly used types. The interior of the valve body is lined with an elastomer seat. Seats may be made of EPDM, buna, viton, Teflon, natural rubber, carbox, chlorbutyl, white buna, or white neoprene as well as other materials. Choice of seat material depends on temperatures, pressures and material handled.

    The seats of some inexpensive butterfly valves are typically molded into the body and cannot be repaired or replaced. Precision butterfly valves typically contain removable seats that are repairable or replaceable.

    Disc
    The valve disc (controlled by the actuator) regulates the flow of material within the conveying line. Disc materials are available to meet a variety of application demands: stainless steel, aluminum/bronze, ductile iron, ductile/epoxy coated, ductile/nickel plated, ductile/nylon II coated as well as others. As the disc is directly in the material flow stream, care must be taken in specifying the proper material of construction and disc shape. Some discs are designed to allow increased flow patterns through the piping.

    Stem
    The stem passes through the center of the valve, attaches to the actuator, and positions the disc for material flow control and shut off. Depending on the application and valve size, stems may be one or two-piece construction. Typical materials of construction include carbon steel and different grades of stainless steel.

    Actuator
    A variety of actuators are available for butterfly valves: manual handle, gear, pneumatic, electric and electro-hydraulic. Also, actuators that may be enclosed in special housings and buried are available for certain underground applications.

    Other considerations
    Depending on the application, additional valve features that may need to be considered. Some of these features include: the manner in which the stem and disc are attached, the way the stem and disc assembly mount inside the valve body, undercutting of disc, type of material used in stem bushings and packing, and availability of a ring seal between the seat and valve body.

    Working with a company that can offer and properly apply a variety of trim features will enhance the success of the butterfly valve in a specific application.

    Applications

    As stated earlier, Butterfly Valves are generally specified for most air, gas, steam, and liquid applications. They offer an excellent, economically priced, positive shut-off valve for handling materials (e.g. gases and liquids) that are easily displaced by the valve disc as it closes. When handling this type of material, butterfly valves provide a reliable, bubble-tight, bi-directional shut off.

    Care must be taken when applying a butterfly valve in semi-abrasive or abrasive dry material applications (this includes slurry applications that contain suspended particles because:
    1) A valve disc closing on dry bulk material will create premature wear to the rubber seat.

    2) The obstructed orifice created by the disc may cause bridging of material on the inlet side of the valve.

    3) A disc opening or closing on a standing column of dry material may cause the material to jam / pack.

    4) Particles of dry material or suspended particles in slurries may become trapped between the disc and seat, causing conveying line inefficiencies.

    Other Types of Butterfly Valves

    As a person becomes familiar with butterfly valves, they will undoubtedly discover other types of butterfly valves on the market. Listed below is a brief introduction to some of these other types.

    Inflatable Seated Butterfly Valves
    Inflatable seated butterfly valves utilize an inflatable seat or bladder to create a seal around the disc. Once the disc is brought to the closed position, the bladder is inflated pneumatically.

    Pros:
    1) Since the seal is created after the disc closes, less torque is required to move the disc into the closed position. A smaller sized actuator costing less money is can be used.

    2) Again, because the seal is created after the disc closes, minimal abrasion exists between the disc and the seat.

    Cons:
    1) In addition to the controls needed to verify the position of the disc, additional controls are needed to identify whether the bladder is inflated or not. These controls add cost to the valve.

    2) The bladder may be damaged and not creating a seal, even though controls identify that a seal has been established.

    3) The valve must be located near an air supply to pneumatically inflate the bladder.

    4) The inflatable bladder is subject to damage and abrasion, requiring periodic replacement.

    High Performance -- Double Offset Butterfly Valve
    This type of butterfly valve is ideal for applications involving higher temperatures (up to 1200º F) and higher pressures (up to 1440 psig). The disc and stem are double offset, causing the disc to “cam” into place upon closure.

    Pros:
    1) A reliable butterfly valve for handling higher temperature and pressure applications.

    Cons:
    1) Cost -- considerably more expensive than standard butterfly valves.


    High Performance -- Triple Offset Butterfly Valve
    This type of butterfly valve is often used in refinery and off shore applications where more extreme conditions exist. Most triple offsets utilize a metal on metal seat and disc closure, are rated up to 600# class, and are fire safe.

    Pros:
    1) A reliable valve for extreme applications.

    Cons:
    1) Cost -- more expensive than the double-offset butterfly valve.


    The double and triple offset butterfly valves are specialized valves for extreme applications.

    Salina Vortex Corporation manufacturers a variety of slide gates, diverter valves and iris valves for handling dry bulk material. Vortex butterfly valves are available for air, steam, liquid and certain dry material applications.

    For additional information, please visit:
    http://www.bulk-online.com/Co/34338.htm
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  2. #2
    Marco Aurelio Flores-Verdugo

    Marco Aurelio Flores-Verdugo

    Consultant

    Tecmen S.A. de C.V.

    Tecmen S.A. de C.V.

    Professional Experience 1 Years / 0 Month Marco Aurelio Flores-Verdugo has 1 Years and 0 Month professional experience

    Discussions 280 Marco Aurelio Flores-Verdugo acceded to 280 discussions, Articles 0 Marco Aurelio Flores-Verdugo wrote 0 articles, Publications 0 Marco Aurelio Flores-Verdugo Flores-Verdugo released 0 publications

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    Know-How Design (138) Marco Aurelio Flores-Verdugo used this tag 138 times, Pneumatic Conveying (75) Marco Aurelio Flores-Verdugo used this tag 75 times, Training (14) Marco Aurelio Flores-Verdugo used this tag 14 times

    Good article .

    Just one question how do yow avoid the leak in high temperature butterfly valves, due to the stem position. Some years ago a well known cement factory bought large diameter buterfly valves for hot gases and some solids and were not able to cope with the leak. (These were not double movement butterfy but single only rotation buterfly). The leak was causing toxic atmosphere in the downstream equipment (mills). It was impossible to give maintenance without being exposed to high CO atmosphere.

    Marco
    TECMEN
    Consultant in:
    Sponge Iron (DRI) handling
    Sponge Iron DRI Automated Storage Firefighting and Root Cause Analysis
    Pneumatic Conveying Consultants
    Phone 5281 8300 4456.

  3. #3
    How suitable are butterfly valves for fire water applications? We are planning to install a butterly valve and put a control on it to control water flow to our domestic water supply tower. The same tower is also used as fire water for residents. Is just a small company residential facility. Although we have butterfly valves for fire fighting applications in the plant, they are deluge valves, hence on and off. How good are these valves for the application we are planning to use them for.

  4. #4
    Marco Aurelio Flores-Verdugo

    Marco Aurelio Flores-Verdugo

    Consultant

    Tecmen S.A. de C.V.

    Tecmen S.A. de C.V.

    Professional Experience 1 Years / 0 Month Marco Aurelio Flores-Verdugo has 1 Years and 0 Month professional experience

    Discussions 280 Marco Aurelio Flores-Verdugo acceded to 280 discussions, Articles 0 Marco Aurelio Flores-Verdugo wrote 0 articles, Publications 0 Marco Aurelio Flores-Verdugo Flores-Verdugo released 0 publications

    Searching nothing specified

    Know-How Design (138) Marco Aurelio Flores-Verdugo used this tag 138 times, Pneumatic Conveying (75) Marco Aurelio Flores-Verdugo used this tag 75 times, Training (14) Marco Aurelio Flores-Verdugo used this tag 14 times

    Very good.

    Of course, within the same type of valves there is a wide quality range. Be sure to check for references for your particular selection.

    Marco
    TECMEN
    Consultant in:
    Sponge Iron (DRI) handling
    Sponge Iron DRI Automated Storage Firefighting and Root Cause Analysis
    Pneumatic Conveying Consultants
    Phone 5281 8300 4456.

  5. #5

    Manual operation

    Hi,

    Does anyone have a operation,maintenance and installation manual for the ADAMS butterfly valve (Type HTK and MAK-T)? Really appreciate if you can share for this manual.

    Thank you.

  6. #6
    You would be better off to contact the manufaturer to get that information.

    In North America
    http://www.adamsvalves-usa.com/index.html

    In Europe
    http://www.adams-armaturen.de/en/adams-valves.html

  7. #7
    Quote Originally Posted by Marco A. Flores View Post
    Good article .

    Just one question how do yow avoid the leak in high temperature butterfly valves, due to the stem position. Some years ago a well known cement factory bought large diameter buterfly valves for hot gases and some solids and were not able to cope with the leak. (These were not double movement butterfy but single only rotation buterfly). The leak was causing toxic atmosphere in the downstream equipment (mills). It was impossible to give maintenance without being exposed to high CO atmosphere.

    Marco
    Normally we suggest our customer use Eccentric metel-seat butterfly valves, you can check below page the details of our butterfly valves.

    http://www.valveu.com/product/butter...utterfly-valve

    Any commnets please let me know.

    Best regards,
    Carl

    info@laparvalve.net
    www.laparvalve.net
    www.laparvalve.com
    Last edited by laparvalve; 2nd July 2014 at 10:22.

  8. #8

    Lapar's Butterfly Valve

    we are the manufacturer of Butterfly Valves with about 10 years experiences, I attached the details of our device to you, hope to enter into good business relationship with your company.

    You can find more details of our valves on our website below, all of Lapar Valves have one year quality warranty.

    http://www.valveu.com/

    Lapar Control valve provide high quality valves and our major products is ball valve, butterfly valve and Control Valve, our customer included Cocacola, Mayora, Veolia, Daikin, CEC, Praxair, APP and etc, you can refer on the below page

    http://www.valveu.com/support/field-application

    Any inquiries please feel free let us know.

    Best regards,
    Carl

    sales@lapar-valve.com
    http://www.valveu.com/
    Last edited by laparvalve; 2nd July 2014 at 10:26.

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