fluid flow valves

8/8/2019 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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fluid flow valves

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