Butterfly Valve - principle,specification & details

Butterfly Valve - principle,specification,Types,Applications

 

What is Butterfly Valve?

A valve may be a quarter-turn motion valve, that's wont to stop, regulate, and begin flow. A valve contains a disc that is mounted on a shaft. once the valve is absolutely closed, the disk utterly blocks the road. once the valve is absolutely opened, the disc is at a right angle to the flow of gas or liquid.
 Butterfly valves zero in size from one into over two hundred in and most have a pressure capability of 150-psi to 740-psi cold operating pressure. the overall temperature rating for a resilient sitting valve is twenty-five Degrees F to three hundred Degrees F and four hundred Degrees F to 450 Degrees F for a superior valve.

Butterfly Valve components:

The valve consists of solely four main components: body, disk, stem. The most vital one is the metal disc. This metal disc is that the one ordinarily stated because of the butterfly. The butterfly is mounted on a rod and once the valve is closed it blocks passage of fluid. once the valve is absolutely open, the metal disc or butterfly moves 1 / 4 flip. The passageway is unrestricted permitting fluids or air to pass.
There square measure several alternative parts that type the valve. They embrace the resilient seat, body, packing, a stem, and an actuator. The resilient seat is mounted on the body of the valve so as to supply the correct seal. The packing provides an extra seal particularly just in case the resilient seal is broken.

Butterfly Valve Types 


  • concentric butterfly valves – this kind of valve contains a resilient rubber seat with a metal disc.
  • Doubly-eccentric butterfly valves and here high-performance butterfly valves or double-offset butterfly valves and here totally different sort of materials is employed for seat and disc.
  • Triply-eccentric butterfly valves -triple-offset butterfly valves and here the seat square measure either laminated or solid metal seat style.


Method of management 


The closure component of a valve consists of a metal circular disc or vane that pivots on AN axis at right angles to the direction of flow within the pipe. once turned on a shaft, the disc seals against seats within the valve body. the skinny disc is often within the passageway however it offers very little resistance to flow. These valves supply a rotary stem movement of ninety degrees or less, in a very compact style. in contrast to ball valves, butterfly valves don't have any pockets during which fluids could become unfree once the valve is closed. The valve operation time is brief as a result of the valving component is turned 1 / 4 communicate open or shut the passageway.

Butterfly Valve Function


  • Butterfly valves may be used for on/off service or strangling. once a valve throttles or modulates the flow it's dominant the speed and capability of media through the valve.
  • A valve for on/off services is sometimes line size and needs the bottom pressure drop offered within the open position.
  • Control valves square measure a crucial part of a fluid handling system. choosing a valve for this perform needs additional calculations and permit for system needs. The user should be able to determine the most flow demand, that loves the planning flow, and most pressure drop allowed, that is provided by the consulting engineer and is sometimes 3 to 5 pounds mostly. This pressure drop ought to ne'er exceed one 1/2 the water pressure.




Butterfly Valve Applications

Butterfly valves may be used across a good variety of applications. They perform well in giant volume water applications and suspension applications. the subsequent square measure some typical applications of Butterfly valves:
•  Cooling water, air, gases, fireplace protection etc.
• suspension and similar services
•  Vacuum service
• aggressive and high-temperature water and steam services
• compressed gas or Gas Applications

Advantages of a valve

Butterfly valves square measure the same as ball valves however have many blessings. they're tiny and, once motivated pneumatically, open and shut terribly quickly. The disc is lighter than a ball, and therefore the valve needs less structural support than a valve of comparable diameter. Butterfly valves square measure terribly precise, that makes them advantageous in industrial applications. they're quite reliable and need little maintenance.

Disadvantages of a valve

One disadvantage of butterfly valves is that some portion of the disc is often bestowed to the flow, even once absolutely opened. the employment of a valve thus continuously leads to a pressure switch across the valve, notwithstanding the setting.