Presentation 1 B W
Transcript of Presentation 1 B W
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ISA Final Control Element ISA
ISA SessionNo. 10
Final ControlElement I
KEVINGIVEN
ISA Final Control Element ISA
Welcome
ISA MEMBERS
ISA Final Control Element ISA
Serge TrudelGeneral Manager
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ISA Final Control Element ISA
Bray International, Inc.Manufacturing Facilities
Canada
USA
Mexico
Hong-Kong
Scotland
Germany
China
Australia
ISA Final Control Element ISA
Final Control Element:
A final control element is amechanical device which producessome predictable series of changes in aprocess in response to an automatedcommand or control signal actingthrough a mechanical, pneumaticelectric or hydraulic actuator.
ISA Final Control Element ISA
F.C.E. Types
Conveyer
Pumps
Motors
Robots
Dampers
Hydraulic cylinders
Control Valves
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Final Control ElementConveyers
Either on-off orvariable speed.
Speed in Unitlength per second.
ISA Final Control Element ISA
Final Control ElementPumps
Pumps are used to supply flow and pressure to aliquid or slurry. Usually used on-off
Also used in control application usually small sizesand less precise control. Can only control one variablemainly flow rate.
ISA Final Control Element ISA
Final Control ElementMotors
A majority of motors are on-off
Variable speed drives
operates pumps, rotary equipment, mixers,
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Final Control ElementRobotics
Widely used in repetitive manufacturing
Hazardous areas
Heavy handling
Precise manufacturing
Microprocessor manufacturing
ISA Final Control Element ISA
Final Control ElementDampers
Gas control
Round or rectangular
Louvers
Automated by rotary actuatoror linear cylinder
Usually sheet metalfabricated for up to 15 PSIpressure
48
ISA Final Control Element ISA
Final Control ElementCylinders and solenoid manifold
Mainly two positions
Bus controlled
Linear motion
Valve operator
Mechanicaldisplacement
Cylinders used onmodulating control
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ISA Final Control Element ISA
Control Valve:
A final control element or variable
resistance which produces somepredictable series of changes in flowquantity, reservoir level, productmixing, temperature or line pressurein response to an automated commandor control signal acting through apneumatic electric or hydraulicactuator.
ISA Final Control Element ISA
Engineers Brew
ISA Final Control Element ISA
Engineers Brew
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ISA Final Control Element ISA
Engineers Brew
ISA Final Control Element ISA
Engineers Brew
ISA Final Control Element ISA
Engineers Brew
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ISA Final Control Element ISA
Engineers Brew
ISA Final Control Element ISA
OPEN LOOP SYSTEM
A SYSTEM DEPENDENT UPON HUMANINTERACTION TO ACHIEVE CONTROL.
ISA Final Control Element ISA
CLOSED LOOP SYSTEM
A closed loop system is a control system capable ofsensing values of a preselected variable and generatingcorrective action without the intervention of a humanoperator
Actu ator
Positionner Controller
Remote
Set Point
Note: While the operator may interact to modify the controldesired, once modified, the operator need not remain involved.
Sensing device
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Control characteristics
This term is generally employed todescribe the relationship which exists
between flow rate through a valve and thevalve travel as the latter varies from full
closed to full open. Control characteristicis given as inherent or as installed.
ISA Final Control Element ISA
Types of characteristics
Inherent characteristic: is therelationship which exists under a normaltest situation where constant pressuredifferential is maintained across the valveat all travel positions.
Installed characteristic: is therelationship which occurs when the valveis installed in a working system, andwhere pressure differential may varydependent upon valve travel and overallsystem characteristics.
ISA Final Control Element ISA
Common characteristics:
Equal percentageLinear
Quick opening
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ISA Final Control Element ISA
Common characteristics:
%Open
Cv
0
20
40
60
80
100
120
140
0 10 20 30 40 50 60 70 80 90 100
Quick Opening
Linear
Equal %
ISA Final Control Element ISA
Common Characteristics
% Open
1000 50
100
10
Equal Percentage
Linear
Quick Opening
1
ISA Final Control Element ISA
Globe valve plug design
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Globe valve plug design
Equal PercentageLinearQuick Opening
ISA Final Control Element ISA
Equal percentage characteristic
Angl e of Previo us New Flow Changeopening flow (gpm) % change gpm) (gpm)
10 100 70 170 70
20 170 70 289 119
30 289 70 491 202
40 491 70 835 344
50 835 70 1,420 585
60 1,420 70 2,413 993
70 2,413 70 4,103 1,690
80 4,103 70 6,975 2,872
90 6,975 70 11,858 4,883
ISA Final Control Element ISA
Equal percentage characteristic
Ang le of Openi ng
Flow
(GPM)
0
2000
4000
6000
8000
10000
12000
10 20 30 40 50 60 70 80 90
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ISA Final Control Element ISA
Selection criteria
If in doubt about the preferred characteristic, choo seequal percentage
Except for pressure relief applications, the quick openingcharacteristic is seldom employed for control applications
Liquid system
If system pressure drop available < 25% choose equalpercentage
If pressure dro p available > 25% choose linear
For pressure control choo se equal percentage
Gas
small volume system choos e equal percentage
large volume system
i) P available > 25% choose linear
ii) P available < 25% choose equal percentage
ISA Final Control Element ISA
Valve authority
Q=1000USGPM
Pp=100psig
Pvalve=50psi
Pcoil=25psi
P pipe=25psi
Valve author ity = 50 = 50%
100
ISA Final Control Element ISA
Valve authority
Q=1000USGPM
Pp=100psig
Pvalve
=25psi
Pcoil=50psi
P pipe=25psi
Valve author ity = 25 = 25%
100
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ISA Final Control Element ISA
Valve authority
ISA Final Control Element ISA
System analysis
6 INCH VALVE, EQUAL % CHARACTERISTIC
PRESSURE SOURCE: RESERVOIR
VALVE CARRIES 75% OF TOTAL SYSTEMDROP
VALVE INLET
ANGLE PRESS. FLOW
90 5 193
80 5 124
70 5 75
60 5 45
50 5 26
40 5 15
30 5 8
20 5 5
10 5 3
Angle of Opening
Flow
(GPM)
0
20
40
60
80
100
120
140
160
180
200
10 20 30 40 50 60 70 80 90
ISA Final Control Element ISA
System Analysis
6 INCH VALVE, LINEAR CHARACTERISTICPRESSURE SOURCE: RESERVOIR
VALVE CARRIES 75% OF TOTAL SYSTEMDROP
VALVE INLET
ANGLE PRESS. FLOW
90 5 19380 5 177
70 5 159
60 5 139
50 5 119
40 5 97
30 5 76
20 5 50
10 5 26Angle of Opening
Flow
(GPM)
0
20
40
60
80
100
120
140
160
180
200
10 20 30 40 50 60 70 80 90
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ISA Final Control Element ISA
System Analysis
6 INCH VALVE, EQUAL % CHARACTERISTIC
PRESSURE SOURCE: PUMP
VALVE CARRIES 25% OF TOTAL SYSTEM DROP
VALVE INLET
ANGLE PRESS. FLOW
90 6.6 128
80 6.8 107
70 7 78
60 7.2 51
50 7.4 31
40 7.6 19
30 7.8 11
20 8 6
10 8.2 4 Angl e of Op ening
Flow
(GPM)
0
20
40
60
80
100
120
140
10 20 30 40 50 60 70 80 90
ISA Final Control Element ISA
System Analysis
6 INCH VALVE, LINEAR CHARACTERISTIC
PRESSURE SOURCE: PUMP
VALVE CARRIES 25% OF TOTAL SYSTEMDROP
VALVE INLET
ANGLE PRESS. FLOW
90 6.6 128
80 6.6 124
70 6.4 117
60 6.7 113
50 7.2 107
40 7.4 96
30 7.6 80
20 7.8 59
10 8.1 33
Angl e of Open ing
Flow
(GPM)
0
20
40
60
80
100
120
140
10 20 30 40 50 60 70 80 90
ISA Final Control Element ISA
System Analysis
6 INCH VALVE, EQUAL % CHARACTERISTIC
PRESSURE SOURCE: PUMPVALVE CARRIES 2% OF TOTAL SYSTEMDROP
VALVE INLET
ANGLE PRESS. FLOW
90 65 114
80 67 113
70 69 109
60 70 97
50 71 77
40 72 53
30 73 32
20 74 20
10 75 12 Angl e of Op enin g
Flow(GPM)
0
20
40
60
80
100
120
10 20 30 40 50 60 70 80 90
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ISA Final Control Element ISA
System Analysis
6 INCH VALVE, LINEAR CHARACTERISTICPRESSURE SOURCE: PUMPVALVE CARRIES 2% OF TOTAL SYSTEMDROP
VALVE INLET
ANGLE PRESS. FLOW
90 45.5 95
80 45.7 95
70 45.9 95
60 46.1 94
50 46.3 94
40 47.3 93
30 48.2 91
20 48.5 84
10 48.9 64Angl e of Open ing
Flow
(GPM)
50
55
60
65
70
75
80
85
90
95
100
10 20 30 40 50 60 70 80 90
ISA Final Control Element ISA
Angle of Opening
Flow
(GPM)
0
20
40
60
80
100
120
140
160
180
200
10 20 30 40 50 60 70 80 90
Angle of Openin g
Flow
(GPM)
0
20
40
60
80
100
120
140
10 20 30 40 50 60 70 80 90
Angle of Opening
Flow
(GPM)
0
20
40
60
80
100
120
10 20 30 40 50 60 70 80 90
Angle of Opening
Flow
(GPM)
0
20
40
60
80
100
120
140
160
180
200
10 20 30 40 50 60 70 80 90
Angle of Opening
Flow
(GPM)
0
20
40
60
80
100
120
140
10 20 30 40 50 60 70 80 90
Angle of Opening
Flow
(GPM)
50
55
60
65
70
75
80
85
90
95
100
10 20 30 40 50 60 70 80 90
ISA Final Control Element ISA
2 Main Valve Divisions
ROTARY
LINEAR
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ISA Final Control Element ISA
ROTARYBALL
BUTTERFLYDAMPER
SEGEMENTED BALL
V or CHARACTERISED BALL
PLUG
SPECIALTY ROTARY
ISA Final Control Element ISA
Butterfly Valve Disc Design
ISA Final Control Element ISA
Conventional Disc
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ISA Final Control Element ISA
Thin Disc
ISA Final Control Element ISA
Contoured
ISA Final Control Element ISA
Single Offset
L
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ISA Final Control Element ISA
Double Offset
L1
L
ISA Final Control Element ISA
Double Offset
ISA Final Control Element ISA
Triple Offset
Third angle is aconstant between sealring and seatingsurface.
Metal Seated
Seal on disc or in Body
Low seat friction
Inherently firesafe
Low or Zero LeakageL1
L
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ISA Final Control Element ISA
Rangeability
THIS IS THE RATIO OF MAXIMUM TO
MINIMUM CONTROL OF FLOW WITHIN THEVALVE'S INHERENT CHARACTERISTICRANGE (i.e. MAXIMUM CV VS MINIMUM CVAT ENDS OF INHERENT CHARACTERISTICSPAN).
RANGEABILITY =Cv
Cv
max.
min.
ISA Final Control Element ISA
Rangeability
CONV. CONT. THIN
CVmin. 34 14 28
CV max. 1,025 1410 2,786
RANGEABILITY 30 100 100
ISA Final Control Element ISA
Rangeability (6 size)
ANGLE S/30 S/20 CONT.
OF OPENING Cv % Cv % Cv %
0 0 - 0 - 0 -
10 6 - 7 - 17 -
20 56 252 59 245 44 158
30 129 153 130 153 80 8240 225 78 227 78 147 84
50 354 60 376 60 241 64
60 567 60 607 60 416 72
70 1,025 61 1,065 61 682 64
80 1,542 55 1,873 64 1,118 64
90 1,850 19 2,786 65 1,410 26
RANGEABILITY 30:1 100:1 100:1
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ISA Final Control Element ISA
CONVENTIONAL DISC
% Open
1000 50
100
1
10
Cv Max
Cv Min
ISA Final Control Element ISA
THIN DISC
% Open
1000 50
100
10
Cv Max
Cv Min1
ISA Final Control Element ISA
Characteristic comparison
% Open
1000 50
100
1
10
Cv Max
Cv Min
Thin
Conventional
ContouredCV
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ISA Final Control Element ISA
Disc Geometry
ISA Final Control Element ISA
Ball Valve
Used in all applications
Equal percentagecharacteristic
Regular of full port design
All type of connections,threaded, socket or buttweld, flanged, RTJ, wafer
Wide rage of seats for hightemp, or high pressures.
ISA Final Control Element ISA
Segmented or V Ball valve
Better Control than withfull port ball (by reducedport )
Lighter valve
Shorter face to face
Multiple pressure classedesign with one body(wafer)
higher recovery thanbutterfly
No cavity to fill
Single or double offset
Multiple characteristics orCv available
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ISA Final Control Element ISA
Rotary ActuatorsPneumatic Rack and Pinion
Compact
0-90, 0-120, 0-135 degrees
Simple and well balancedModular design, installedin any orientation
NAMUR accessories
Operates in pressure from40-120 PSIG
Not as affected bydynamic torque changes
Used in 2 position andcontrol applications
Double Acting or Springreturn
S90
S91
ISA Final Control Element ISA
Rotary ActuatorsPneumatic Diaphragm
Largest rotary actuator
Works at pressures as lowas 3-15 PSI
Used in 2 position andcontrol applications
Always spring return
0-90 degrees operation
ISA Final Control Element ISA
Rotary ActuatorsPneumatic Scotch yoke
Similar to Rotary diaphragmmixed with Rack & Pinion
Used in large valve operation
mechanical advantage due tohigh pressure piston designcoupled with an internal leveradvantage
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ISA Final Control Element ISA
Rotary ActuatorsElectric
Simple installation
No air needed, no dryers, nofilters
Standard with position limitswitches, manual override,electrical inputs for on-off orcontrol, feedback analog,digital control, etc.
Slow operation, eliminateswater hammer
ISA Final Control Element ISA
Positionner
Acts as a servo to an inputsignal
Insures that the valvemoves to the proper inputsignal by controling outputpower to the valve to openor close
Analog Pneumatic,
Analog Electropneumatic,
Analog Electronic
Analog Smart
Digital Smart
ISA Final Control Element ISA
Set Point
A TERM USED TO DESCRIBE THE VALUE AT WHICH ACONTROLLER WILL ATTEMPT TO MAINTAIN ACONTROLLED VARIABLE. FOR EXAMPLE, IF ACONTROLLER IS TO MAINTAIN A SYSTEM PRESSURE OF 50
psig, THIS VALUE IS THE SET POINT.
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ISA Final Control Element ISA
Hysteresis
0 20 40 60 80 100
0
5
10
15
Valve travel (%)
Hysteresis (%)Control
Signal
ISA Final Control Element ISA
Dead Time
THE TIME WHICH ELAPSES BETWEEN ACHANGE IN INPUT AND THE INITIALRESPONSE TO THAT CHANGE.
ISA Final Control Element ISA
Dead Band
THE MINIMUM CHANGE IN INPUT SIGNALWHICH WILL RESULT IN ANY DETECTABLEMOVEMENT OF THE VALVE. EXPRESSED IN
PER CENT OF FULL INPUT SIGNAL SPAN.
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ISA Final Control Element ISA
Proportional Band
RELATIONSHIP THAT INDICATES THAT THEPER CENT CHANGE IN OUTPUT SIGNAL IS APER CENT MULTIPLE OF THE CHANGE INTHE MEASURED VARIABLE.
ISA Final Control Element ISA
Positioner
USED TO ACCURATELY RELATE VALVETRAVEL POSITION PROPORTIONAL TOMAGNITUDE OF A CONTROL SIGNAL.
ISA Final Control Element ISA
Pneumatic PositionerCommon signal ranges.
3-9
9-15
3-15 psig
psig Split Range
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ISA Final Control Element ISA
Split Range
Flow = 60 to 1000 GPM
60 to 500 GPM (3 to 9 psi)
500 to 1000 GPM (9 to 15 psi )
ISA Final Control Element ISA
PositionerSpan.
ALGEBRAIC DIFFERENCE BETWEEN UPPERAND LOWER RANGE VALUES.
i.e. 3 - 15 psig RANGE
12 psig SPAN
ISA Final Control Element ISA
PositionerDirect Acting.
INCREASED INPUT GIVES INCREASEDOUTPUT.
i.e. 3 psig @ 0 open
15 psig @ 90 open
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ISA Final Control Element ISA
PositionerReverse Acting.
INCREASED INPUT GIVES DECREASED
OUTPUT.
i.e. 3 psig @ 90 open
15 psig @ 0 open
ISA Final Control Element ISA
LINEARGLOBE
NEEDLE
ANGLE
DE-SUPERHEATER
PINCH
GATE
KNIFE GATE
CONE OR ANNULAR
ISA Final Control Element ISA
Globe Valve DesignTypical control valve
Precise control
50:1 rangeability
High pressure recovery
Handles high pressure drop
Avai labl e in ANSI 125-2500
Expensive in sizes 3 and
higher
Low Cv for size
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ISA Final Control Element ISA
Corrosion Resistant Globe
Typical globe characteristics
Teflon lined internals
Characterized trims
Aggressive corrosiveapplications
ISA Final Control Element ISA
Steam Conditioner
Steam pressure and
temperature reduction
Internal condensate injection
in the vena-contracta
instantly produc es saturated
lower pressure steam to
increase efficiency.
ISA Final Control Element ISA
Pinch Valve
Mainly a slurry on-off orcontrol valve
Used in abrasive process
Full port
No-Cavity
Non Blocking
Fully lined
multiple elastomersavailable
Zero leakage in solids
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ISA Final Control Element ISA
Knife Gate
Typical on-off
Used in control onlarge valves
Pulp and paper andSlurry valve
TAPPI dimensions
ISA Final Control Element ISA
Cone Valve
Power plant bypass
flood control or irrigation
drain reservoirs
Submerged or freedischarge (by free jet orconfined jet).