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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