Download - Fluid flow Valves

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    DEPARTMENT OF CHEMICAL ENGINEERING

    Presented by: GROUP 4

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    Muhammad Usman (08-chem-02-B)

    Anam Asghar (08-chem-06-B)

    Saqib Raouf (08-chem-26-B)

    Arooba Arooj (08-chem-44-B)

    Syed Tahir Ali Rizvi (08-chem-58-B)

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    VALVESVALVES

    Used in piping systems and processing vessels or tanks.Used in piping systems and processing vessels or tanks.

    FUNCTIONSFUNCTIONS

    OnOn--off serviceoff service

    Throttling serviceThrottling servicePrevention of reverse flowPrevention of reverse flow

    Pressure controlPressure control

    Special functionsSpecial functions

    Directional flow controlDirectional flow control Sampling serviceSampling service

    Limiting flowsLimiting flows

    Sealing vessels or tank outlet nozzlesSealing vessels or tank outlet nozzles

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    Flow

    Liquid

    Gas

    Regulators

    Automatic

    Manual

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    Valves RepresentationValves Representation

    Valves are represented by the symbol

    Manual valves are represented as

    Automatic valves are represented as

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    HOW VALVES

    OPERATE?Manual valves

    Automatic valves

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    AUTOMATIC VALVES

    Automatic ControlThrough

    Servo

    motor

    solenoid

    valves

    Pneumatic

    control

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    Manual

    OperatedBy Hand

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    Basic Components of a ValveBasic Components of a Valve

    Regardless of types, all valves havefollowing basic parts

    o Body

    o Bonnet

    o Actuator

    o Packing

    o Trim (internal elements)

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    Body (shell)Body (shell)

    Primary pressure boundary of valve

    Framework that holds everything together

    Receives inlet & outlet piping

    Resists fluid pressure loads from connecting piping

    Shape ranges from simple block to high complexshapes

    Ease of manufacture, assembly & cost decide theshape of body

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    BonnetBonnet

    The cover for the opening in thevalve body is Bonnet.

    In some designs, the body itself issplit into two sections that bolttogether.

    2nd principle pressure boundary ofvalve.

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    TrimTrim

    Internal Elements of a valve are collectively referredto as valves Trim.

    Typically it includes

    Disk

    Seat

    Stem Sleeves (needed to guide the stem)

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    DiskDisk

    Provides capability for permittingand prohibiting fluid flow.

    For a valve having bonnet, disk is thethird primary principle pressureboundary

    Disk is the pressure retaining part ofa valve.

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    Seat (Seal Rings)Seat (Seal Rings)

    Provides seating surface for the disk

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    StemStem

    The stem, which connects the actuator and thedisk, is responsible for the positioning the disk.

    It is not a pressure boundary part

    Two types of valve stems are there

    Rising stems:

    Stem will rise above actuator as valve is opened

    Non Rising stems:

    Stem will not rise above actuator as valve is opened

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    ActuatorActuator

    Actuator in simple words is the Handle with which we open or close thevalve.

    Actuator operates the disk & stem assembly.

    It may be a

    a) Manually operate hand wheel

    b) Manual lever

    c) Motor operated

    d) Solenoid operated

    e) Pneumatic operated

    f) Hydraulic ram

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    PackingPacking

    Most valves use form of packing toprevent leakage from the spacebetween the stem and the bonnet.

    Packing is commonly a fibrous material(such as flax) or another compound(such as Teflon)

    These materials forms a seal between

    the internal parts of a valve and theoutside where the stem extendsthrough the body

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    Types of valvesTypes of valves

    Valves are classified according to their seat design.Seat is a part of valve.

    However, according to their different workingprinciples & different uses they can be classifiedinto a no. of ways.

    For example; they can be classified according totheir use as shown

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    TYPES OF VALVESTYPES OF VALVES

    General purposevalves

    Gate valve

    Globe valve

    Plug valve

    Ball valve

    Butterfly valve

    Diaphragm valve

    Pinch valve

    Slide valve

    CheckCheck valvesvalves

    Swing valveSwing valve

    Titling valveTitling valve

    Lift valveLift valve

    Spring loadedSpring loaded

    valvevalve

    SpecialSpecial serviceservice

    valvesvalves

    Pressure reliefPressure relief

    valvevalve

    Control valveControl valve

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    Types of valvesTypes of valves

    Multi TurnValves

    o Gate valve

    o Globe valve

    o Diaphragm

    valve

    o Needle valve

    Quarter

    TurnValve/Rotary

    Valves

    o Ball valve

    o Butterflyvalve

    SelfActuated

    Valve

    o The checkvalve

    o Pressurerelief valve

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    Gate valveGate valve

    A gate valve, also known as asluice valve, is a valve that opensby lifting a round or rectangulargate/wedge out of the path of thefluid.

    Typical gate valves should never beused for regulating flow, unlessthey are specifically designed forthat purpose.

    Gate valves are characterised ashaving either a rising or a non-

    rising stem. Rising stems provide avisual indication of valve position.Non-rising stems are used wherevertical space is limited orunderground.

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    Uses of gate valveUses of gate valve

    For Fully opened or fully closedoperations

    In applications that involve viscousliquids such as heavy oils, light

    grease and other non flammableviscous liquids.

    Problem:-

    One of the most commonproblems with the gate valve is

    that the valve packing can dry outand cause the valve to leak at theshaft.

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    Plug valvePlug valve

    Plug valves are valves with cylindrical orconically-tapered plugs which can berotated inside the valve body to controlflow through valve.

    The plugs in the plug valves have one ormore hollow passageways going sidewaysthrough the plug , so that fluid can flowthrough the plug when the valve is open.

    The simplest and most common general

    example of plug valve is a 2-port valve,which has two positions ,open to allowthe flow and shut to stop the flow.

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    Uses and advantagesUses and advantages

    Nonthrotling on-off operationssuitable for corrosion ,abrassive,

    and critical service applications.

    Advantages:

    Minimum resistance to flow and

    low pressure drop.

    Easily adapted to multi port

    construction.

    Plug valves are usually made frombrass , bronze, stainless steel, steel

    etc.

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    Globe valveGlobe valve

    A globe valve is a type of valve usedfor regulating flow in a pipeline,

    consisting of a movable disk-typeelement and a stationary ring seat

    in a generally spherical body.

    Globe valves are linear motionvalves with round bodies, from

    which their name is drives.

    Typically, automated valves usesliding stems.

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    UsesUses

    Used for:

    Regulating fluid flow in bothoff/on and throttling services

    High pressure drops and highpressure applications

    Used where some fluid trappedin line is not objectionable.

    Typically globe valves are madeof metallic alloys.

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    UsesUses

    Ball valves are durable and usuallywork to achieve perfect shutoff evenafter years of disuse. They aretherefore an excellent choice forshutoff applications.

    Used for:

    Suitable for wide pressure range.

    Quick opening.

    Advantages:minimum resistance to flowminimum to moderate temperatureservices.

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    SAQIB RAOUF

    08-Ch-26

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    TYPESOFVALVESTYPESOFVALVES

    Buterfly valve

    Pinch valve

    Diphgram valve

    Slide valve

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    BUTTER

    FLY

    VALVE

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    DESIGN :DESIGN :

    A smooth circular disc is positioned in themiddle of the pipe mounting connection iseither welding connection or betweenflanges

    Rotating the handle turns the plate either

    parallel or perpendicular to the flow ofwater, shutting off the flow.

    TYPES :

    Wafer connection

    Flanged connection

    Lugged connection

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    PINCH VALVEPINCH VALVE

    Includes any valve with a flexible elastomerbody that can be pinched closed, cutting offflow using a mechanism or fluid pressure

    SOME ADVANTAGES Low maintenance cost

    Low weight due to large plastic body

    Low pressure drop

    Moderate temperature services

    Excellent drainage,ease of cleaning

    Straight through design allowing for a highrate of flow with minimal turbulance

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    On-off and throttling services

    Handling of slurries,liquids with large amounts of suspended solids

    Used in wastewater,powder,pellets and medical applications Suitable for food applications when utilised with a food grade

    sleeve

    PINCH VALVE DESIGN A flexible hose is pinched between one or two moving external

    elements to stop the flow

    Pinching action is made by air or hydraulic pressure placed directlyon the elastomer sleeve

    USED FOR:

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    This image shows the operating principle of a double acting

    pinch valve. Double acting pinch valves close from two

    directions. The flow control valve may be operated manually

    using a handwheel or automatically opened / closed using

    pneumatic, hydraulic or electric motor.

    DOUBLE ACTING PINCH VALVE

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    DIAPHRAGM VALVEDIAPHRAGM VALVE

    D

    iaphragm valves use an elastomeric diaphragm toseparate the flow stream from the closure element

    Their application is generally as shut-off valves inprocess systems within the food and beverage,pharmaceutical and biotechnology industries

    USED FOR: Handling of slurries, highly

    corrosive materials or materials to be protected fromcontamination

    ADVANTAGES:

    Low operating pressures

    Fully opened, fully closed or throttling services

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    DESIGN:DESIGN:

    The flexible diaphragm isconnected to a compressorby a stud molded into thediaphragm

    MATERIAL OFMATERIAL OF

    CONSTRUCTION:CONSTRUCTION:

    Cast ironCast iron Cast steelCast steel

    PVCPVC

    ColypropyleneColypropylene

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    SLIDE VALVESLIDE VALVE

    Slide valves tend to come in two different designs

    Wedge gate type

    Parallel slide type

    Both types of valves are used as manually operatedvalves

    For automatic actuation parallel slide type is chosen

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    Wedgegate valve

    parallel slide valve

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    SLIDE VALVEDESIGN

    Flow is controlled by means of a gate or

    blade which slides between parallel bodyseats

    The blade is completely removed from the

    fluid way when the valve is in open position

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    AdvantagesAdvantages

    Simple to set up

    Easy to maintain

    Lasting for a long period with minimal maintenance

    APPLICATIONS:

    Handling liquids or gases containing a high percentage ofsolids,pulp stock and free flowing granular materials

    Controlling low pressure flow of gases, liquids, suspensions and

    fluidized solid

    Applications where tight closure is not required

    Coping with a wide range of power and speed demands

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    Check valvesCheck valves

    A check valve is a mechanicaldevice which normally allows thefluid (liquid or gas) to flowthrough it only in one direction.

    Check valves are two-port valvesmeaning they have two openingsin the body one for fluid to enterand the other for fluid to leave

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    Check valves (cont)Check valves (cont)

    Check valves are also known asclack valve or one way valve.

    Check valves work automatically

    and they are not controlled by aperson or any external control

    The bodies (external shells) ofmost check valves are made of

    plastic or metal

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    Types of check valvesTypes of check valves

    There are different types ofcheck valves:

    Swing check valve

    Lift check valve

    Tiltng disc check valve

    Spring loaded check valve desgn

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    Swing check valveSwing check valve

    They allow full unobstructed

    flow opening with line pressureand automatically closing aspressure decreases.

    Swing check valves are usuallyinstalled in conjunction with gatevalves because they providerelatively free flow.

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    UsesUses

    Used for:

    Minimum resistance tounobstructed flow.

    Low velocities.

    Infrequent change of direction.

    Service in lines with gate valves.

    Although swing check valves cancome in various sizes, large checkvalves are often swing checkvalves.

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    Lift check valvesLift check valves

    A lift-check valve is a check valve inwhich the disc, sometimes called a

    lift, can be lifted up off its seat byhigher pressure of inlet or upstream

    fluid to allow flow to the outlet or

    downstream side.

    When the pressure is no longerhigher, gravity or higher downstreampressure will cause the disc to loweronto its seat, shutting the valve to

    stop reverse flow

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    UsesUses

    Used for:

    Piping system in which globevalves are being used as the flow

    control valve.

    Frequently change direction.

    Recommended with globe andangle valves.

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    Tilting disc check valvesTilting disc check valves

    They keep fluid resistance andThey keep fluid resistance andturbulance low because of itsturbulance low because of itsstraight through design likestraight through design likeswing check valveswing check valve

    USED FOR:USED FOR:

    Liquid or gas servicesLiquid or gas services

    Minimum resistance to flowMinimum resistance to flow Frequent change of directionFrequent change of direction

    Service lines using gate valvesService lines using gate valves

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    UsesUses

    Used for:

    Liquid or gas service.

    Easy maintenance, respond tocertain water pressure.

    Never jam or stick due to rust orcorrosion.

    Not contaminating the sensitivefluids that come into contactwith them.

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    Types of pressure valvesTypes of pressure valves

    Relief valves:(RV) automatic system that

    relief by static pressure on a liquid. Itspecifically open proportionally withpressure increasing.

    Safety valves:(SV) automatic system that

    relieve static pressure on a gas. Itspecifically opens almost straight tofull lift after a pop sound.

    Safety relief valves:(SRV) automatic system

    that relief by static pressure on bothgas and liquid.

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    Types (cont)Types (cont)

    Low pressure safety valve:(LPSV)

    automatic system that relief by staticpressure on a gas. The pressure issmall and near the atmospheric

    pressure..

    Low and vacuum pressure safetyvalves:

    (LVPSV) automatic system that reliefby static pressure on a gas. Thepressure is small, negative or positiveand near the atmospheric pressure.

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    UsesUses

    Used for:

    Relieving excessive pressuresdeveloped by incompressiblefluids.

    Available from cryogenictemperatures up toapproximately 1500 degree F andfrom full vacuum to 1000 psi .

    The area exposed to the overpressure is the same whether thevalve is open or closed

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    Control valvesControl valves

    Control valves are valves used tocontrol conditions such as flow,

    pressure, temperature, and liquidlevel by fully or partially opening or

    closing.

    The opening or closing of controlvalves is done by means of electrical,

    hydraulic or pneumatic systems .

    The most common and versatiletypes of control valves are sliding-stem globe and angle valves

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