Control Valve Types

WHEN ACCURACY MATTERS

IntroductionIntroductiontoto

Control Valve TypesControl Valve Types

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• IEC Definition: A power operated device which changes the fluid flow rate in a process control system. It consists of a valve connected to an actuator that is capable of changing the position of the closure member in the valve in response to a signal from the system

• ISA Definition: A power operated device which modifies the fluid rate in a process control system. It consists of a valve connected to an actuator mechanism that is capable of changing the position of a flow controlling element in the valve in response to a signal from the controlling system.

Control Valve DefinitionControl Valve Definition

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5050PSIGPSIGTANKTANK

PCSupply

Steam

P1 = 75-100 psig

Positioner

Analog Electro-Pneumatic Control Signal4-20mA

Process Variable4-20mA

Where does a CV fit in the Control SystemWhere does a CV fit in the Control System

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• Feature– Ruggedly built for high cycle

service

– Always provides tight shutoff

– Valve bore approximates line size

– Always provide system effect with travel change

– Used to alter flow in response to control signal

– “Absorbs "large amount of energy

• On-Off Valve– No

– Yes

– Yes

– No

– No

– No

• Control Valve– Yes

– No

– No

– Yes

– Yes

– Yes

Control Valve vs On/Off ValveControl Valve vs On/Off Valve

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Typical Isolation Valves Typical Isolation Valves

HP Butterfly Full Port Ball Sleeve Lined Plug Manual Globe Manual Gate

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Control Valve Hierarchy Control Valve Hierarchy

Pressure Drop

HPBV Ball Rotary Globe

Globe Severe Duty

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Control Valve TypesControl Valve Types

• Reciprocating– Globe

– Angle

– Severe Service

• Rotary– Butterfly

– Ball

– Rotary Globe

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Basic Butterfly ValvesBasic Butterfly Valves

Poor Control Valve

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High Performance Butterfly ValvesHigh Performance Butterfly Valves

Better Control

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Types of Butterfly ValvesTypes of Butterfly Valves

Concentric Centerline

Single Offset (Eccentric)

Double Offset (HPBV)

2

1

2

1

3

Tripple Offset

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Ball ValvesBall Valves

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Segmented Ball Segmented Ball Control ValveControl Valve

Un-Restricted Flow Path

Un-Restricted Flow Path

Partially Open

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Segmented Ball ValvesSegmented Ball Valves

• Partial Ball – 90 Deg. Rotation• High Capacity & High Turndown• Characterized Segmented Ball• Single Metal or Soft Seat

Notice the Single Clamped Seat

Notice the Characterization

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Eccentric Rotary GlobeEccentric Rotary Globe

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CAMFLEX AnimationCAMFLEX Animation

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Reciprocating Control ValvesReciprocating Control Valves

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Single Port Unbalanced Single Port Unbalanced

• Globe Valve• Unbalanced Design• Post Guided• Lo-dB Trim • Class-IV & Class-V Shut-

Off• Flow To Open• Flow To Close

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LEAKAGE CLASSESLEAKAGE CLASSES

• CL IV, Standard– .01% of Rated Cv

• CL V, Optional– Reduced Pressure Drop Capability Due

to Higher Seat Loads Required

• CL VI, Optional– Plug with PTFE Seal Ring

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QUICK CHANGE TRIMQUICK CHANGE TRIM

• Maintenance Advantage

• Seat Ring Held in Place by the Seat Ring Retainer (A Type of Cage)

• Seat Ring Gasket Required

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TRIM TYPESTRIM TYPES

• Contoured Trim– Full Area– Reduced Area

• Single Stage Lo-dB and Anti-Cavitation

• Two-Stage Lo-dB and Anti-Cavitation

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LOW NOISE PRODUCTSLOW NOISE PRODUCTS

• LO-DB Trim Reduces the Sound Level up to 15 dBA Over Conventional Trim, Depending on the P1/P2 Ratio.

SINGLE-STAGE Lo-dB TRIM

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Angle Single Port UnbalancedAngle Single Port Unbalanced

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Venturi Seat RingVenturi Seat Ring

Extreme Conditions

High Pressure Drops

Sever Coking Conditions

Flashing Liquids

Emergence Blow Down

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Single Port Balanced Single Port Balanced

• Globe Valve

• Fully-Balanced Design

• Cage Guided

• Composite Polymer Balancing Seal

• Class-V Shut-Off

• Flow To Open

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Single Port BalancedSingle Port Balanced

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CAGE GUIDED VALVESCAGE GUIDED VALVES

• The cage provides positive alignment and control of the plug

• The cage can modify or “characterize” the flow

The Cage Serves Two Major Functions

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CAGE GUIDED - PRESSURE BALANCEDCAGE GUIDED - PRESSURE BALANCED

TYPICAL APPLICATIONS• Clean Process Fluids• High Pressure, High Temperature, Noise, and

Cavitation

LIMITATIONS• Slurries or Gritty or Dirty Processes• Less Capacity Compared to Rotary Valves• Larger and Heavier than Most Rotary Valves

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CAGECAGE

• Acts as Sealing Surface for Plug Seal Ring

• Retains Seat Ring

• Provides Throttling Orifice

• Guiding Surface

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SEAL RINGSSEAL RINGS

• Metal Seal Ring– Class II – Temp: -320oF to 650oF

• PTFE Seal with Backup– Meets Class IV Seat Leakage– Temp: -20oF to 300oF

• Graphite Seal Ring– Meets Class IV Seat Leakage– Temp: -320oF to 1050oF

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Pressure Energized Seal RingPressure Energized Seal Ring

• Pressure Energized PTFE Plug Seal

• Class V Leakage• Max Temp: 450oF

(600oF)• Uni-Directional• Higher Shutoff

Capability

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AUXILIARY PLUGAUXILIARY PLUG

• Flow-To-Close Direction Only

– Approx. 10 dB Less Attenuation Than F-T-O

• Tight Shutoff at High Temperature

• Class IV, Class V Leakage

• “Dead” Travel in Closed Position = 0.050”

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AUXILIARY PLUGAUXILIARY PLUG

• Cage Guided• Balanced• Single Seated• Captured Seat Ring (QC)• Pilot Trim

Stem

Packing Ring (S)

Cage

Balancing Seal

Packing Follower

Auxiliary Pilot Plug

Body

Seat Ring

Guide Bushing

Plug (Main)

Bonnet

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Double Port (Semi Balanced)Double Port (Semi Balanced)

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3-Way3-Way

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80000 Series 3 Way80000 Series 3 Way

80000 Series 3 Way

DivertingCombining

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Bellows SealBellows Seal

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Low / Micro FlowLow / Micro Flow

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End ConnectionsEnd Connections

Raised Face (RF)

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End ConnectionsEnd Connections

Weld Prep

Butt Weld

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End ConnectionsEnd Connections

Socket Weld

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End ConnectionsEnd Connections

Ring Type Joint (RTJ)

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End ConnectionsEnd Connections

Clamp Connection

(Graylok,ReFlange)

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End ConnectionsEnd Connections

Threaded (NPT,MS)

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Flangeless

End ConnectionsEnd Connections

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End ConnectionsEnd Connections

Separable Flange

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Questions? Questions?