control valves2
TRANSCRIPT
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FIDECTraining Center
Control Valves
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FIDEC(Training Center)
Category of ValvesValves
Manual valves Automated valves
Modulating valvesModulating valves are moreover categorized into 2 types.
These valves are operatedautomatically.
Control Valves
On-Off valvesSelf Operated valves Control valves
On-Off valves just put the flow “on” or “off” . On the other word, let the flow medium run or stop. There types of valves are mainly used for sequential control or rough control like air conditioning.
Self-operated valves operate receiving energy from fluid pressure of fluid temperature. It has high responsibility but generally is not good at accuracy.
Control valves operate receiving energy from compressed air, electric power, etc. used with controllers and sensors. Control valves and related equipment realizes most accurate control.
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FIDEC(Training Center)
Introduction
What Is A Control Valve? The control valve manipulates a flowing fluid, such as gas, steam, water, or chemical compounds, to compensate for the load disturbance and keep the regulated process variable as close as possible to the desired set point.
The control valve assembly typically consists of the:
* Valve body
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Valve body* The internal trim parts* An actuator to provide the motive power to operate the valve* A variety of additional valve accessories, which can include positioners,
transducers, supply pressure regulators, manual operators, snubbers, or limit switches.
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FIDEC(Training Center)
Roles of control valves
Flow Orifice, Flow meterPress.Transmitter
Processparameters Sensor Control Valve
Pressure
Controller
D.P. Transmitter
4-20mA4-20mA
Control Valves
Temp.
LevelTransmitterTemperatureTransmitter
Level
Orifice
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FIDEC(Training Center)
Example of process controlFlow control
FC
BoilerBoiler feed pomp
Pressure control
PC
Boiler
T bi b l
Turbine
Control Valves
Minimum flow control valve Turbine bypass valve
Level control
LCReactor
Temperature control
TC
Heat exchanger
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FIDEC(Training Center)
Component parts
ActuatorPositioner
Control Valves
Body
Yamatake Standard Single Seated Valve
Convert electrical signal to pneumatic signal so that valve can operate using pneumatic energy.
Control valve travel so that correct amount of fluid runs inside valve.
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FIDEC(Training Center)
Structure of actuator and valve body
Diaphragm
Spring
Gasket
Convert pneumatic energy to force
Convert force to displacement
Control Valves
Valve Body Seat RingValve Plug
Gasket
Trim modulates flow passage to control flow rate.
Seal the space between valve body and bonnet
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FIDEC(Training Center)
Introduction
Control Valves [email protected]
Major Component of Typical Control Valve Body
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FIDEC(Training Center)
Introduction Rain capEye boltDiaphragmSpringActuator stemDiaphragm case
Scale plateStem connectorYoke
Packing flangePacking follower
Actuator
Control Valves [email protected]
gYoke claming nutGland packingValve stemBonnet
Stud bolt and nutGasketGuide ringGuide bushingValve plugSeat ringValve body
Body Trim
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FIDEC(Training Center)
Combination of body and actuatorControlvalves
Actuator
Pneumatic HydraulicMotorized
Control Valves
Body
Glove Angle Butterfly
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FIDEC(Training Center)
Features of each actuator types
Pneumatic type Hydraulic type Motorized type
Response time Dead time is rather long. Action speed is fast.
Dead time is short. Action speed is fast
No dead time. Action speed is slow
Maintaining safety position at supply fail time
Possible by using integrated spring or connecting volume tank easily and certainly.
Difficult to maintain Can stop and maintain only the position at an emergency time.
Output power Middle for spring diaphragm type. Big for piston cylinder t
Small for oil integrated type. Big for oil separated i t ll ti t
Bigger than pneumatic type and oil pressure type
Control Valves
type. installation type
Structure Simple Complicated Complicated
Weather proof and Exprosion proof
Not necessary Should be considered Should be considered
Air piping or electric wiring Simple Simple for oil integrated type. Complicated for oil separated installation
Simple
Maintenance work Easy Complicated Complicated
Cost Reasonable Expensive Expensive
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FIDEC(Training Center)
Features of each body types
Control
Linearmotion
Glove valve
3-3. Cage valve
3-2. Top & Bottom guided valve
3-4. Angle valve
3-5. Tree-way valve
3-1. Single seated valve
Control Valves
Valves
Rotarymotion
3-6. Diaphragm valve
Gate valve
3-7. Rotary valve
3-8. Butterfly valve
Ball valve
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FIDEC(Training Center)
Cv calculationWhen you decide port size of control valve, you need to calculate required Cv value with fluid condition given on control valve data sheet. Then, you can specify appropriate Rated Cv value and port size.At this chapter, most popular Cv calculation formula that is established by FCI (Fluid Controls Institute, Inc.) is introduced.
What is Cv value ?One of the popular coefficients that express flow capacity. Cv value us defined as follows.Fl f 60 d F (15 6 d C) l i h h i f US l/
Control Valves
Flow rate of 60 degF (15.6 degC) clean water with the unit of US gal/ min at differential pressure of 1 psi and specific travel of valve.-Rated Cv value: Cv value at a valve is fully opened.-Required Cv value: Cv value calculated with fluid condition
water 60degF
1 psi US gal/min
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Introduction
Flow Control CharacteristicsAs the actuator moves the valve plug through its travel range, the unobstructed flow area changes in size and shape depending on the contour of the valve plug.
When a constant pressure differential is maintained across the valve, the changing relationship between percentage of maximum flow capacity and percentage of total travel range can be portrayed , and is designated as the inherent flow characteristic
f th l
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of the valve.
Commonly specified inherent flow characteristics include:
* Linear Flow Characteristic * Equal-Percentage Flow Characteristics * Quick-Opening Flow Characteristic
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Introduction
Linear Flow Characteristic
Cv = K . L
(K: Constant, L: Valve plug travel)
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Equal-Percentage Flow Characteristics
Inherent Flow Characteristics Curves
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Introduction
Quick-Opening Flow Characteristic
Control Valves [email protected]
Typical Construction to Provide Quick-OpeningFlow Characteristic
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Introduction
Selection of Flow Characteristic
Control Valves [email protected]
Liquid Level Systems
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FIDEC(Training Center)
Introduction
Rangeability
“Rangeability” denotes the ratio between the maximum flow rate and the minimum flow rate which can be controlled by a control valve.
Inherent rangeability = imumCvimumCv
minmax
��
Control Valves [email protected]
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FIDEC(Training Center)
Control Valves
Valve and Actuator Types
Control ValvesThe control valve regulates the rate of fluid flow as the position of the valve plug or disk is changed by force from the actuator. To do this, the valve must:
* Contain the fluid without external leakage;* Have adequate capacity for the intended service;
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q p y ;* Be capable of withstanding the erosive, corrosive, and temperature influences
of the process; and* Incorporate appropriate end connections to mate with adjacent pipelines and
actuator attachment means to permit transmission of actuator thrust to the valve plug stem or rotary shaft.
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Valve Bodies
Globe Valves
Single-Port Valve Bodies
Control Valves [email protected]
Single-Ported Globe-StyleValve Body
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Valve Bodies
•Most Popular type•Valve plug has only one seat to shut-of fluid
•Seat leakage is low even though it has metal seat
•Unbalancing fluid force is higher than pressure balancing type
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p g yp•When required valve size is lower than 2 inch,
This type is most advantageous because small sized actuator can be mounted.
•That means price is reasonable.•When required size is larger than 2 inch,
generally, price is not reasonable because the larger the valve size is, the bigger the actuators size is comparing single seated type to pressure balancing type.
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Valve Bodies
Valve PlugGasket
Control Valves [email protected]
Valve BodySeat Ring
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TTop and Bottom Guided valve
•The valve plug is guided at top and bottom.
•Pressure balanced type.•This type is used mainly for oil refinery
industry.
Control Valves [email protected]
•Generally, seat leakage is larger than single seated valves.
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CCage valve
� This type comes after single seated type in market.� Valve plug is guided by cage (shaped like pipe and set in
valve body. It has window that consists of flow characteristics.)
� Pressure balanced type is more popular than unbalanced type.
� For pressure balanced cage type, actuator size is smaller than single seated type when body size is same. Therefore price is more competitive than single seated type when valve size larger than 3 inch or used with high-
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type when valve size larger than 3 inch or used with highpressure rating.
� This type can reduce cavitation erosion and aerodynamic noise that are typical control valve claim.
� Generally, seat leakage is larger than single seated valve.
Seat ring Valve plug
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Valve Bodies
High Capacity, Cage-Guided Valve Bodies
Control Valves [email protected]
High Capacity Valve Body with Cage-Style Noise Abatement Trim
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AAngle valve
•Center of inlet and outlet of valves are right angle.
•This type is advantageous for erosive or abrasive fluid.
•Also used because of piping design advantage.
•Wetted parts design is simpler than general 2way valves. So this type is also advantageous for viscous fluid
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for viscous fluid.
Erosion: Destruction of valve bodies or trims due to high fluid velocity
Abrasion: Erosion due to slurry that contains solids or particles.
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wway valve-Tree
Three-Way Valve Bodies
•Diverting type is used to separate flow to 2 way.•Mixing type is used to mix 2 flow.
•Mainly used for temperature control.
Control Valves [email protected]
Diverting typeMixing type
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Diaphragm Valve•Elastic diaphragm made with rubber and PTFE modulatethe flow passage.
•Wetted parts can be lined with several materials (PTFE, Glass, and rubbers). So this type is advantageous for slurry or corrosive fluid.
•This type is cost effective.
Full open
Control Valves
Full open
Control
Full close
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Valve Bodies
Rotary ValvesButterfly Valve Bodies
� A disk that is almost same diameter as pipe size rotate so as to modulates flow.
� Valve capacity is highest for all types of valves.
� Generally this type is used at pressure
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High-PerformanceButterfly Control Valve
� Generally, this type is used at pressure rating 300# or lower. For higher-pressure rating, this type cannot be applied.
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Valve Bodies
V-Notch Ball Control Valve Bodies
Control Valves [email protected]
Rotary-Shaft ControlValve with V-Notch Ball
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Eccentric-Disk Control Valve Bodies
Center of the plug rotating point is eccentric from the center of valve body.
CV capacity is bigger than that of other globe valves.
Fluid can be passed easily because of straight trough construction.
Control Valves [email protected]
Eccentric-DiskRotary-Shaft Control Valve
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PTFE Valve
•A branch of single seated control valve.
•Especially used for corrosive fluid.
•All wetted parts are made with PTFE, which resist most of acids and alkalis.
•Body has rigid stainless
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Plug: PTFE with 304ss core
Casing: SUS304
Body: PTFE
Bellows: PTFE
casing to avoid warp with piping stress.
•Applicable pressure and temperature is limited.
•Max Operating Temperature: 140 deg C
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PVC / Polypropylene Valve
A branch of single seated control valve.Especially used for corrosive fluid.All wetted parts are made with PVC or Polypropylene, which resist most of acids and alkalisApplicable pressure and temperature
Control Valves
Model VNP
Max Operating Temperature: PVC: 50 deg C, Polypropylene: 80 deg C
Applicable pressure and temperature is limited.Cheaper than PTFE valve
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Ceramic Valve•Wetted part materials are all ceramics
•All wetted parts are made with ceramics that resists most of acids and alkalis.
•3.Highest abrasion resistance.
•4. There are application limitations for temperature, pressure and seat leakage class.
Ceramic
Control Valves
Ceramic
0.4<CVModel HMC 120<CV<13Model HIC
99% aluminum ceramic or Silicon carbide ceramic
Aluminum ceramic: 70 deg C
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Valve Plugs
Types of Valve Plugs
Cage
Plug for cage valve
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Contoured plug
EQ% Linear
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Cage-Guided
Characterization of Cage-Guided Valve Bodies
Control Valves [email protected]
Characterized Cages for Globe-Style Valve Bodies
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End Connections
Control Valve End Connections
Control Valves [email protected]
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Bonnets
Valve Body BonnetsThe bonnet of a control valve is that part of the body assembly through which the valve plug stem or rotary shaft moves.
Control Valves [email protected]
Typical Bonnet, Flange, and Stud Bolts
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Bonnets
Extension Bonnets
Control Valves [email protected]
Extension Bonnet Valve Body withFabricated Extension Bonnet
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Packing
Control Valve Packing
Control Valves [email protected]
Single PTFE V-Ring Packing
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Packing
Control Valves [email protected]
Comprehensive Packing Material Arrangementsfor Globe-Style Valve Bodies
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Packing
Control Valves [email protected]
Typical ValveStem Packing Assemblies
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Packing
PTFE V-Ring
Laminated and Filament Graphite
Single PTFE V-Ring Packing
ENVIRO-SEAL_ PTFE Packing
Control Valves [email protected]
ENVIRO-SEAL PTFE Packing System
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Packing
V-PTFE #4519 yarnV7132Y
Control Valves [email protected]
y
Graphite (T2200) TK2006
V7132Y
SM636
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Gaskets
Examples on Uses of GasketsSerrated metal gasket
Spiral gasket
M d l ACP
Control Valves [email protected]
V8590V543 V543 PTFE coated
Serrated metal gasket Spiral gasket
Model HTS Model ACP
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Grease
Lubricator
Control Valves [email protected]
PS6 #800 #400 #650
Lubricator
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Valve Plug Guiding
Valve Plug Guiding
1. Cage Guiding
Control Valves [email protected]
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Valve Plug Guiding
3. Stem Guiding
Control Valves [email protected]
Left view
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Valve Plug Guiding
4. Top-and-Bottom Guiding
Control Valves [email protected]
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Valve Plug Guiding
5. Port Guiding
Control Valves [email protected]
Right view
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Valve Plug Guiding
Restricted-Capacity
Control Valve Trim
Control Valves [email protected]
Adapter Method for Providing Reduced Flow Capacity
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Actuators
Actuators
Pneumatically operated control valve actuators are the most popular type in use, but electric, hydraulic, and manual actuators are also widely used.
The spring-and-diaphragm pneumatic actuator is most commonly specified due to its dependability and simplicity of design. Pneumatically operated piston actuators provide high stem force output for demanding service conditions.
Control Valves [email protected]
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Actuators
Control Valves [email protected]
Field-Reversible Multi-Spring Actuator
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Actuators
Control Valves [email protected]
Diaphragm Actuator for Rotary Shaft Valves
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Actuators
2. Piston Actuators
Control Valves [email protected]
Control Valve withDouble-Acting Piston Actuator
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Actuators
3. Electrohydraulic Actuators
Control Valves [email protected]
Control Valve with Double-Acting ElectrohydraulicActuator and Handwheel
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Actuators
4. Manual Actuators
Control Valves [email protected]
Typical Manual Actuators
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Actuators
5. Rack and Pinion Actuators
Control Valves [email protected]
Typical Rack and PinionActuator
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Actuators
6. Electric Actuators
Traditional electric actuator designs use an electric motor and some form of gear reduction to move the valve. Through adaptation, these mechanisms have been used for continuous control with varying degrees of success.
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FIDEC(Training Center)
Actuators
7. Types (Directions) of Valve and Actuator Actions
Types of valve and actuator actions should be correctly selected for fail-safe plant operation when the driving power (air supply) has failed. The type (direct and reverse) are defined as follows:
(a) Direct action: Valve opens when driving power has failed.(b) Reverse action: Valve closes when driving power has failed.
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FIDEC(Training Center)
Positioners
Control Valve AccessoriesPositionersPneumatically operated valves depend on a positioner to take an input signal from a process controller and convert it to valve travel. These instruments are available in three configurations:
1. Pneumatic Positioners
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2. Analog I/P Positioner
3. Digital Controller
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Positioners
1. Pneumatic Positioners: A pneumatic signal (usually 3-15 psig) is supplied to the positioner.
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FIDEC(Training Center)
Positioners
2. Analog I/P Positioner
This positioner performs the same function as the one above, but uses electrical current(usually 4-20 mA) instead of air as the input signal.
3. Digital ControllerAlthough this instrument functions very much as the Analog I/P described above, it differs in that the electronic signal conversion is digital rather than analog. The di it l d t th t i
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digital products cover three categories.
* Digital Non-Communicating
* HART
* Fieldbus
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FIDEC(Training Center)
Positioners
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Modern Control ValvesUtilizing Digital Valve Controllers
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FIDEC(Training Center)
Positioners
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Positioner Schematic for Piston Actuator
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Other Accessories
Other Control Valve Accessories
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Top-Mounted Handwheelfor Direct-Acting Diaphragm Actuator
Top-Mounted Handwheelfor Reverse-Acting Diaphragm Actuator
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Other Accessories
Limit Switches
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Cam-Operated Limit Switches
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Other Accessories
Supply Pressure Regulator
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Supply Pressure Regulatorwith Filter and Moisture Trap
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Other Accessories
Fail-Safe Systems for Piston Actuators
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Other Accessories
Electro-Pneumatic Transducers
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Electro-Pneumatic Transducer Mounted on a Diaphragm-Actuated Control Valve
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FIDEC(Training Center)
Other Accessories
Electro-Pneumatic Valve Positioners
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Other Accessories
Diagnostics
Digital valve controllers incorporate predefined instrument and valve diagnostics within firmware to provide alerts if there are problems with instrument mounting, electronics, hardware or valve performance.
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FIDEC(Training Center)
Seat Leakage Classifications
Standards and ApprovalsControl Valve Seat Leakage Classifications(In accordance with ANSI/FCI 70�2 and IEC 60534-4)
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FIDEC(Training Center)
Cavitation and Flashing
Cavitation and Flashing
Choked Flow Causes Flashing and Cavitation
The IEC liquid sizing standard calculates an allowable sizing pressure drop, ���������� ���������� ���� ��������������� ������ ������� �� ��������� ������ ��conditions of P1 and P2������� �� ��������������� �� ��� ������������������������may occur.
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The change is from the liquid state to the vapor state and results from the increase in fluid velocity at or just downstream of the greatest flow restriction, normally the valve port.
Vena Contracta Illustration
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FIDEC(Training Center)
Cavitation and Flashing
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Comparison of PressureProfiles for High and Low Recovery Valves
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FIDEC(Training Center)
Cavitation and Flashing
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Typical Appearance ofFlashing Damage
Typical Appearance ofCavitation Damage
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FIDEC(Training Center)
Noise Prediction
Noise Prediction
1. Aerodynamic
The method defines five basic steps to a noise prediction:
1. Calculate the total stream power in the process at the vena contracta.
2. Determine the fraction of total power that is acoustic power
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2. Hydrodynamic
3. Convert acoustic power to sound pressure.
4. Account for the transmission loss of the pipewall and restate the sound pressure at the outside surface of the pipe
5. Account for distance and calculate the sound pressure level at the observer’s location
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FIDEC(Training Center)
Noise Prediction
Noise Control
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Valve Trim Design for Reducing Aerodynamic Noise
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FIDEC(Training Center)
Noise Prediction
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Valve and Inline Diffuser Combination
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FIDEC(Training Center)
Noise Prediction
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Valve and VentDiffuser Combination
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FIDEC(Training Center)
Noise Prediction
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Special ValveDesign to Eliminate Cavitation
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FIDEC(Training Center)
Noise Prediction
Noise Summary
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Globe Style Valvewith Noise Abatement Cage for Aerodynamic Flow
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FIDEC(Training Center)
Noise Prediction
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Ball Style Valve with Attenuator to ReduceHydrodynamic Noise