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CREATE COMPONENTS OF
BUTTERFLY VALVEAND THEN ASSEMBLE THEM
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Introduction
A butterfly valveis a valve which can be used for isolatingor regulating flow. The closing mechanism takes the form of
a disk.
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 disceither parallel or perpendicular to the flow
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BASIC COMPONENTS
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Body
Butterfly valves generally have bodies that fit between two pipe
flanges. The most common body designs are lug and wafer. The
lug body has protruding lugs that provide bolt holes matching
those in the pipe flange. A wafer body does not have protruding
lugs. The wafer valve is sandwiched between the pipe flanges,and the flange bolts surround the body.
Each type of body has advantages, some of which are listed:
The wafer style is less expensive than a lug style.
Wafer designs do not transfer the weight of the piping systemdirectly through the valve body.
A lug body allows dead-end service or removal of downstream
piping.
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DiskThe flow closure member of a butterfly valve is the disk.
Many variations of the disk design have evolved relative to
the orientation of the disk and stem in an attempt to
improve flow, sealing and/or operating torque.
The disk is the equivalent of a plug in a plug valve, gate in
a gate valve or a ball in a ball valve.
Rotating the disk one-quarter turn or 90 Degrees opens
and closes the butterfly valve.
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Stem
The stem of the butterfly valve may be a one-piece shaft
or a two-piece (split-stem) design.
The stem in most resilient seated designs is protected
from the media, thus allowing an efficient selection of
material with respect to cost and mechanical properties.
In high-performance designs, the stems are in contact
with the media and, therefore, must be compatible, as
well as provide the required strength for seating and
unseating the disk from the seat.
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Seat
The seat of a resilient-seat butterfly valve utilizes an
interference fit between the disk edge and the seat to
provide shutoff.
The material of the seat can be made from many different
elastomers or polymers. The seat may be bonded to the
body or it may be pressed or locked in.
Metal seats are also offered in high-performance butterfly
valves. These metal seats allow a butterfly valve to be
used in even higher temperatures to 1,000 Degrees F.
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Characteristics
Linear:The flow rate is directly proportional to the
amount of disk travel .For example, at 50% open, the flow
rate is 50% of maximum flow.
Equal percentage :Equal percentage characteristic
means that equal increments of valve travel produce
equal percentage changes in flow rate as related to the
flow rate that existed at the previous travel position.
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Applications
A Butterfly Valve can be used in many different fluid
services and they perform well in slurry applications. The
following are some typical applications of Butterfly Valves:
Cooling water, air, gases, fire protection etc.
Slurry and similar services
Vacuum service
High-pressure and high-temperature water and steam
services
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Advantages of Butterfly Valves Compact design requires considerably less space,
compared to other Valves Light in weight
Quick operation requires less time to open or close
Available in very large sizes
Low-pressure drop and high-pressure recovery
Disadvantages of Butterfly Valves Throttling service is limited to low differential pressure
Cavitation and choked flow are two potential concerns
Disc movement is unguided and affected by flowturbulence
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11/12Dimensions of the Body
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Top View of the Arm
