Presentation 1 B W

7/29/2019 Presentation 1 B W

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ISA Final Control Element ISA

ISA SessionNo. 10

Final ControlElement I

KEVINGIVEN


Welcome

ISA MEMBERS


Serge TrudelGeneral Manager


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Bray International, Inc.Manufacturing Facilities

Canada

USA

Mexico

Hong-Kong

Scotland

Germany

China

Australia


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.


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.


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.


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


Final Control ElementDampers

Gas control

Round or rectangular

Louvers

Automated by rotary actuatoror linear cylinder

Usually sheet metalfabricated for up to 15 PSIpressure

48


Final Control ElementCylinders and solenoid manifold

Mainly two positions

Bus controlled

Linear motion

Valve operator

Mechanicaldisplacement

Cylinders used onmodulating control


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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.


Engineers Brew


Engineers Brew


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Engineers Brew


Engineers Brew


Engineers Brew


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Engineers Brew


OPEN LOOP SYSTEM

A SYSTEM DEPENDENT UPON HUMANINTERACTION TO ACHIEVE CONTROL.


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.


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.


Common characteristics:

Equal percentageLinear

Quick opening


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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 %


Common Characteristics

% Open

1000 50

100

10

Equal Percentage

Linear

Quick Opening

1


Globe valve plug design


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Globe valve plug design

Equal PercentageLinearQuick Opening


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


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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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


Valve authority

Q=1000USGPM

Pp=100psig

Pvalve=50psi

Pcoil=25psi

P pipe=25psi

Valve author ity = 50 = 50%

100


Valve authority

Q=1000USGPM

Pp=100psig

Pvalve

=25psi

Pcoil=50psi

P pipe=25psi

Valve author ity = 25 = 25%

100


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Valve authority


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


System Analysis

6 INCH VALVE, LINEAR CHARACTERISTICPRESSURE SOURCE: RESERVOIR


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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System Analysis


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


System Analysis

6 INCH VALVE, LINEAR CHARACTERISTIC

PRESSURE SOURCE: PUMP


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


System Analysis


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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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


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


2 Main Valve Divisions

ROTARY

LINEAR


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ROTARYBALL

BUTTERFLYDAMPER

SEGEMENTED BALL

V or CHARACTERISED BALL

PLUG

SPECIALTY ROTARY


Butterfly Valve Disc Design


Conventional Disc


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Thin Disc


Contoured


Single Offset

L


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Double Offset

L1

L


Double Offset


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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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.


Rangeability

CONV. CONT. THIN

CVmin. 34 14 28

CV max. 1,025 1410 2,786

RANGEABILITY 30 100 100


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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CONVENTIONAL DISC

% Open

1000 50

100

1

10

Cv Max

Cv Min


THIN DISC

% Open

1000 50

100

10

Cv Max

Cv Min1


Characteristic comparison

% Open

1000 50

100

1

10

Cv Max

Cv Min

Thin

Conventional

ContouredCV


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Disc Geometry


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.


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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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


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


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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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


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


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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Hysteresis

0 20 40 60 80 100

0

5

10

15

Valve travel (%)

Hysteresis (%)Control

Signal


Dead Time

THE TIME WHICH ELAPSES BETWEEN ACHANGE IN INPUT AND THE INITIALRESPONSE TO THAT CHANGE.


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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Proportional Band

RELATIONSHIP THAT INDICATES THAT THEPER CENT CHANGE IN OUTPUT SIGNAL IS APER CENT MULTIPLE OF THE CHANGE INTHE MEASURED VARIABLE.


Positioner

USED TO ACCURATELY RELATE VALVETRAVEL POSITION PROPORTIONAL TOMAGNITUDE OF A CONTROL SIGNAL.


Pneumatic PositionerCommon signal ranges.

3-9

9-15

3-15 psig

psig Split Range


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Split Range

Flow = 60 to 1000 GPM

60 to 500 GPM (3 to 9 psi)

500 to 1000 GPM (9 to 15 psi )


PositionerSpan.

ALGEBRAIC DIFFERENCE BETWEEN UPPERAND LOWER RANGE VALUES.

i.e. 3 - 15 psig RANGE

12 psig SPAN


PositionerDirect Acting.

INCREASED INPUT GIVES INCREASEDOUTPUT.

i.e. 3 psig @ 0 open

15 psig @ 90 open


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PositionerReverse Acting.

INCREASED INPUT GIVES DECREASED

OUTPUT.

i.e. 3 psig @ 90 open

15 psig @ 0 open


LINEARGLOBE

NEEDLE

ANGLE

DE-SUPERHEATER

PINCH

GATE

KNIFE GATE

CONE OR ANNULAR


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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Corrosion Resistant Globe

Typical globe characteristics

Teflon lined internals

Characterized trims

Aggressive corrosiveapplications


Steam Conditioner

Steam pressure and

temperature reduction

Internal condensate injection

in the vena-contracta

instantly produc es saturated

lower pressure steam to

increase efficiency.


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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Knife Gate

Typical on-off

Used in control onlarge valves

Pulp and paper andSlurry valve

TAPPI dimensions


Cone Valve

Power plant bypass

flood control or irrigation

drain reservoirs

Submerged or freedischarge (by free jet orconfined jet).

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Presentation 1 B W