types of valves-1

8/18/2019 Types of Valves-1

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Types of valves

According to EN 736-1, a positioning element (e.g. valve) in a system of pipes, tans, mac!ines,"!as t!e p#rpose of

s$itc!ing (on%off) and & on%off d#ty, isolating d#ty or

seting (continio#s%intermittent) & mod#lating d#ty, step-control d#tya fl#id or s#'stance. .

alves are categoried according to t!e movement of t!e t!rottling 'ody $it! reference to t!e flo$ direction,and t!e operating principle of t!eir seal.T!e category of valve determines t!e act#ator type and t!e re*#ired o#tp#t s!aft of t!e act#ater.

pl#g valve A linear movement of t!e dis $it! or against t!e flo$.+n t!e EN position t!e flo$ is over or against t!e dis.

'all valvesT!e 'all in t!e 'ody rotates /0 a'o#t aial s!afts.

+n t!e EN position t!e flo$ r#ns t!ro#g! t!e 'all.

'#tterfly valvesThe disk in the valve rotates about the stem through an angle of 90°.

In the OPEN position the flow runs around the ontrol bod!.

gate valvesT!e gate moves in a linear direction across t!e flo$.

+n t!e EN position t!e flo$ r#ns t!ro#g! t!e valve 'ody.

plug valve

ball valve butterflyvalve

gate valve


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"#$PE %& 'E()E*O('$T

"#$PE %& 'E()E*O('$T

) Definition of outside spindle diameter Da (mm or inch).

Tae t!e meas#rement of t!e diameter or of t!e circ#mference. 2ivide t!e circ#mference 'y p.emar4 it mig!t 'e a t!read 'asing on inc!-system5

2) Definition of length L of 10 thread profiles (mm or inch)

3) Calculation of pitch (mm or inch)

$it! single t!read4 % 1/$it! do#'le t!read4 % 8


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emar4 pitc! of spindle t!reads, 'asing on inc!-system, can also 'e specified 'y 9n#m'er oft#rns per inc!9.

!pecification e"ample

+onnetion flange

name dimensions (in mm)n#m'er of

scre$s

2+N311/

I"O,-0

/IN

1

I"O

,-

2+N311/

I"O,-0

,-

/IN1

/IN

0

I"O,-0

,-

/IN1

/IN

0

I"O,-0

,-

/IN1

/IN

0

I"O,-0

,-

/IN1

/IN

0

I"O

,-0

,-

/IN

1

/IN

0

I"O,-0

,-

/IN1

d d d- d- 234 d 2d4 d5 h h

6 6 *0, 6 7, 6 , 6 ,0 6 ' 7 6 - 56 *08 *08 6 900 6 , 6 80 6 ' 1 6 - 5

) 0 *0 *0 -, -, 70 80 0- 0- ' 0 ' 0 : 5

6 *- *- 6 ,0 6 1, 6 -, 6 ' - 6 - 5

)- *5 *5 8, 8, 00 00 50 50 ' 7 ' 7 5 5 : 5

) *7 *7 -0 -0 0 0 7, 7, ' -0 ' -0 , ,5

5


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)5 *-, *-, 00 00 70 -00 -,5 -,5 ' 7 ' 7 , 8 ; 1

), *0 *0 ,0 ,0 10 -0 00 -91 ' -0 ' -0 , , ; 1

)7 *, *, 50 5, --0 -70 ,7 ,7 ' 0 ' 0 , , ; 1

)8 *50 *50 58, 58, -0 00 507 507 ' 7 ' 7 1 1 ; 1

1) ma val#e

different dimensions 'et$een 2+N 3


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lease tae t!e environmental conditions into acco#nt $!en dimensioning and specifying anact#ator.

T!e $!ole positioning #nit (t!e act#ator and t!e valve as a #nit) !as to 'e dimensioned properly.nly in t!is case t!e positioning #nit $ill f#nction $it!o#t restrictions, relia'le and safe.

T!e on-site conditions comprise t!e follo$ing environmental factors4

>limaticonemoderate limate

old limate

tropial limate

?o#nting arrangement Open air: outdoor or indoor

=pecial am'ient conditions#eat: radiation: dust:aggressive atmosphere: vibration:.et.

2egree of protection aording to EN70,-9

?ode of operation aording to ;/E0,0

perating met!odtight losing:

travel dependent lose: et.

>ontrol of t!e act#atoronventional:

inverter driven

Age and maintenance stat#s

Information re


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14 "peed number of revolutions

94 Positioning angle

04 Travel

4 Positioning time

-4 Positioning speed

4 *ore re


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"#$PE %& 'E()E*O('$T

*igure 961.6T!pes of globe valve bodies.

re;E".6 )ate valves are used when a straight6line flow of fluid and minimum restrition isdesired. )ate valves are so named beause the part that either stops or allows flow through the valve ats

somewhat like the opening or losing of a gate and is alled: appropriatel!: the gate. The gate is usuall!

wedge shaped. Bhen the valve is wide open: the gate is full! drawn up into the valve: leaving an opening

for flow through the valve the same siCe as the pipe in whih the valve is installed. Therefore: there is little pressure drop or flow restrition through the valve. )ate valves are not suitable for throttling purposes sine

the ontrol of flow would be diffiult due to valve design and sine the flow of fluid slapping against a

partiall! open gate an ause eAtensive damage to the valve. EAept as speifiall! authoriCed: gate valves

should not be used for throttling.

)ate valves are lassified as either (I"IN)"TE' or NON(I"IN)6"TE' valves. On the nonrising6stem

gate valve shown in figure 969 the stem is threaded on the lower end into the gate. $s the handwheel on

the stem is rotated: the gate travels up or down the stem on the threads: while the stem remains vertiall!

stationar!. This t!pe of valve almost alwa!s has a pointer6t!pe indiator

"#$PE %& 'E()E*O('$T

*igure 969.6+utawa! view of a gate valve 2nonrising6stem t!pe4.

threaded onto the upper end of the stem to indiate valve position.

The rising6stem gate valve: shown in figure has the stem attahed to the gateD the gate and stem rise and

lower together as the valve is operated.


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)ate valves used in steam s!stems have fleAible gates. The reason for using a fleAible gate is to prevent

binding of the gate within the valve when the valve is in the losed position. Bhen steam lines are heated:

the! will eApand: ausing some distortion of valve bodies. If a solid gate fits snugl! between the seat of a

valve in a old steam s!stem: when the s!stem is heated and pipes elongate: the seats will ompress againstthe gate: wedging the gate between them and lamping the valve shut. This problem is overome b! use of

a fleAible gate 2two irular plates attahed to eah other with a fleAible hub in the middle4. This design

allows the gate to fleA as the valve seat ompresses it: thereb! preventing lamping.

@TTE(*>? ;$>;E".6 The butterfl! valve: one t!pe of whih is shown in figure 96- ma! be used in a

variet! of s!stems aboard ship. These valves an be used effetivel! in freshwater: saltwater: FP6,: *6872naval distillate4: lube oil: and hill water s!stems aboard ship. The butterfl! valve is light in weight:

relativel! small: relativel!

"#$PE %& 'E()E*O('$T

*igure 96-0.6+utawa! view of a gate valve 2rising6stem t!pe4.

"#$PE %& 'E()E*O('$T

*igure 96-.6@utterfl! valve.


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To lose or open a butterfl! valve: turn the handle onl! one


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$s we have seen: most valves an be lassified as being either stop valves or hek valves. "ome

"#$PE %& 'E()E*O('$T

*igure 96-.6"top6hek valve.

valves: however: funtion either as stop valves or as hek valves6depending on the position of the valvestem. These valves are known as "TOP+#E+3 ;$>;E".

$ stop6hek valve is shown in ross setion in figure 96-. This t!pe of valve looks ver! muh like a lift6

hek valve. #owever: the valve stem is long enough so when it is srewed all the wa! down it holds the

disk firml! against the seat: thus preventing an! flow of fluid. In this position: the valve ats as a stop

valve. Bhen the stem is raised: the disk an be opened b! pressure on the inlet side. In this position: thevalve ats as a hek valve: allowing the flow of fluid in onl! one diretion. The maAimum lift of the disk

is ontrolled b! the position of the valve stem. Therefore: the position of the valve stem limits the amountof fluid passing through the valve even when the valve is operating as a hek valve.

"top6hek valves are widel! used throughout the engineering plant. "top6hek valves are used in man!drain lines and on the disharge side of man! pumps.

"peial6Purpose ;alves

There are man! t!pes of automati pressure ontrol valves. "ome of them merel! provide an esape for

pressures eAeeding the normal pressureD some provide onl! for the redution of pressureD and some

provide for the regulation of pressure.


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"#$PE %& 'E()E*O('$T

*igure 96-,.6Pressure6reduing 2spring6loaded4 valve.

"P(IN)6>O$/E/ (E/+IN) ;$>;E"."pring6loaded reduing valves: one t!pe of whih is shown in

figure 96-, are used in a wide variet! of appliations. >ow6pressure air reduers and others are of this t!pe.

The valve simpl! uses spring pressure against a diaphragm to open the valve. On the bottom of thediaphragm: the outlet pressure 2the pressure in the redued pressure s!stem4 of the valve fores the disk

upward to shut the valve. Bhen the outlet pressure drops below the set point of the valve: the spring

pressure overomes the outlet pressure and fores the valve stem downward: opening the valve. $s the

outlet pressure inreases: approahing the desired value: the pressure under the diaphragm begins tooverome spring pressure: foring the valve stem upwards: shutting the valve. ?ou an adGust the

downstream pressure b! removing the valve ap and turning the adGusting srew: whih varies the spring

pressure against the diaphragm. This partiular spring6loaded valve will fail in the open position if a

diaphragm rupture ours.

(E'OTE6OPE($TIN) ;$>;E".6(emoteoperating gear is installed to provide a means of operatingertain valves from distant stations. (emote6operating gear ma! be mehanial: h!drauli: pneumati: or

eletri.

"ome remote6operating gear for valves is used in the normal operation of valves. *or eAample: the main

drain s!stem manual valves are opened and losed b! a reah rod or a series of reah rods and gears. (eah

rods ma! be used to operate engine6room valves in instanes where the valves are diffiult to reah fromthe operating stations.

Other remote6operating gear is installed as emergen! e


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pressure is at least as high as the redued pressure desired4 and regardless of the amount of redued

pressure fluid that is used.

;arious designs of pressure6reduing valves are in use. Two of the t!pes most ommonl! found on gas

turbine ships are the spring6loaded reduing valve 2alread! disussed4 and the air6pilot operated diaphragm

reduing valve.

$ir6pilot operated diaphragm ontrol valves are used eAtensivel! on naval ships. The valves and pilots are

available in several designs to meet different re


14/28

"#$PE %& 'E()E*O('$T

*igure 96-8.6/iaphragm ontrol valve: downward6seating t!pe.

In the diaphragm ontrol valve: operating air from the pilot ats on the valve diaphragm. The

superstruture: whih ontains the diaphragm: is diret ating in some valves and reverse ating in others. If the superstruture is diret6ating: the operating air pressure from the ontrol pilot is applied to the TOP of

the valve diaphragm. If the superstruture is reverse6ating: the operating air pressure from the pilot is

applied to the N/E("I/E of the valve diaphragm.

*igure 96-8 shows a ver! simple t!pe of diretating diaphragm ontrol valve with operating air pressure

from the ontrol pilot applied to the top of the valve diaphragm. "ine the valve in the figure is a

downward6seating valve: an! inrease in operating air pressure pushes the valve stem downward toward thelosed position.

Now look a figure 96-1. This is also a diretating valve with operating air pressure from the ontrol pilot

applied to the top of the valve


15/28

"#$PE %& 'E()E*O('$T

*igure 96-1.6/iaphragm ontrol valve: upward6seating t!pe.

diaphragm. Note that the valve shown in figure 96-1 is more ompliated than the one shown in figure 96-8

beause of the added springs under the seat. The valve shown in figure 96-1 is an upward6seating valve

rather than a downwardseating valve. Therefore: an! inrease in operating air pressure from the ontrol pilot tends to OPEN this valve rather than to lose it.

$s !ou have seen: the air6operated ontrol pilot ma! be either diret ating or reverse ating. The

superstruture of the diaphragm ontrol valve ma! be either diret ating or reverse ating. $nd: the

diaphragm ontrol valve ma! be either upward seating or downward seating. These three fators: as well asthe purpose of the installation: determine how the diaphragm ontrol valve and its air6operated ontrol pilot

are installed in relation to eah other.

To see how these fators are related: letHs onsider an installation in whih a diaphragm ontrol valve and its

air6operated ontrol pilot are used to suppl! ontrolled steam pressure.


16/28

*igure 96-9.6$rrangement of ontrol pilot and diaphragm ontrol valve for suppl!ing redued6steam

pressure.

*igure 96-9 shows one arrangement that !ou might use. $ssume that the servie re


17/28

"#$PE %& 'E()E*O('$T

*igure 960.6Priorit! valve.

P(IO(IT? ;$>;E".6 In s!stems with two or more iruits: it is sometimes neessar! to have some means

of suppl!ing all available fluid to one partiular iruit in ase of a pressure drop in the s!stem. $ priorit!

valve is often inorporated in the s!stem to ensure a suppl! of fluid to the ritialvital iruit. The

omponents of the s!stem are arranged so the fluid to operate eah iruit: eAept the one ritialvitaliruit: must flow through the priorit! valve. $ priorit! valve ma! also be used within a subs!stem

ontaining two or more atuating units to ensure a suppl! of fluid to one of the atuating units. In this ase:

the priorit! valve is inorporated in the subs!stem in suh a loation that the fluid to eah atuating unit:eAept the ritialvital unit: must flow through the valve.

*igure 960 shows one t!pe of priorit! valve. ;iew $ of figure 960 shows the valve in the priorit!6flow

positionD that is: the fluid must flow through the valve in the diretion shown b! the arrows to get to the

nonritialvital iruits or atuating units. Bith no fluid pressure in the valve: spring tension fores the

piston against the stop and the poppet seats against the hole in the enter of the piston. $s fluid pressureinreases: the spring ompresses and the piston moves to the right. The poppet follows the piston: sealing

the hole in the enter of the piston until the preset pressure is reahed. 2The preset pressure depends upon

the re


18/28

"#$PE %& 'E()E*O('$T

*igure 96.6;alve manifold showing utawa! view of the valves and t!pial ombination of sution anddisharge valves.

Bhen the pressure in the valve reahes ,00 psi: the poppet reahes the end of its travel. $s the pressure

inreases: the piston ontinues to move to the right: whih unseats the poppet and allows flow through the

valve: as shown in view $ of figure 960. If the pressure drops below ,00 psi: the ompressed spring

fores the piston to the left: the poppet seats: and flow through the valve stops.

*igure 960 view @: shows the priorit! valve in the free6flow position. The flow of fluid moves the poppetto the left: the poppet spring ompresses: and the poppet unseats. This allows free flow of fluid through the

valve

;$>;E '$NI*O>/"

"ometimes sution must be taken from one of man! soures and disharged to another unit or units of

either the same or another group. $ valve manifold is used for this t!pe of operation. $n eAample of suh amanifold 2fig. 964 is the fuel oil filling and transfer s!stem where provision must be made for the transfer

of oil from an! tank to an! other tank: to the servie s!stem: or to another ship. If: for eAample: the purpose

is to transfer oil from tank No. to tank No. 5: the disharge valve for tank No. 5 and the sution valve

from tank No. are opened: and all other valves are losed. *uel oil an now flow from tank No. : throughthe sution line: through the pump: through the disharge valve: and into tank No. 5. The manifold sution

valves are often of the stop6hek t!pe to prevent draining of pumps when the! are stopped.

;$>;E #$N/B#EE> I/ENTI*I+$TION $N/ +O>O( +O/IN)

;alves are identified b! markings insribed on the rims of the handwheels: b! a irular label plate seured

b! the handwheel nut: or b! label plates attahed to the shipHs struture or to the adGaent piping.

Piping s!stem valve handwheels and operating levers are marked for training and asualt! ontrol purposeswith a standardiCed olor ode. +olor ode identifiation is in onformane with the olor sheme of table

96. Implementation of


19/28

Table 96.6;alve #andwheel +olor +ode

this olor sheme provides uniformit! among all naval surfae ships and shore6based training failities.

'$INTEN$N+E

Preventive maintenane is the best wa! to eAtend the life of valves and fittings. $lwa!s refer to the

appliable portion of the "tandard Nav! ;alve Tehnial 'anual: N$;"E$ 09516>P0-6,000: if possible.

Bhen making repairs on more sophistiated valve t!pes: use the available manufaturerHs tehnialmanuals. $s soon as !ou observe a leak: determine the ause: and then appl! the proper orretive

maintenane. 'aintenane ma! be as simple as tightening a paking nut or gland. $ leaking flange Gointma! need onl! to have the bolts tightened or to have a new gasket or O6ring inserted. /irt and sale: if

allowed to ollet: will ause leakage. >oose hangers permit setions of a line to sag: and the weight of the pipe and the fluid in these sagging setions ma! strain Goints to the point of leakage.

Bhenever !ou are going to install a valve: be sure !ou know the funtion the valve is going to perform6that

is: whether it must start flow: stop flow: regulate flow: regulate pressure: or prevent bakflow. Inspet the

valve bod! for the information that is stamped upon it b! the manufaturer= t!pe of s!stem 2oil: water: gas4:operating pressure: diretion of flow: and other information.

?ou should also know the operating harateristis of the valve: the metal from whih it is made: and the

t!pe of end onnetion with whih it is fitted. Operating harateristis and the material are fators that

affet the length and kind of servie that a valve will giveD end onnetions indiate whether or not a

partiular valve is suited to the installation.

Bhen !ou install valves: ensure the! are readil! aessible and allow enough headroom for full operation.Install valves with stems pointing upward if possible. $ stem position between straight up and horiContal is

aeptable: but avoid the inverted position 2stem pointing downward4. If the valve is installed with the stem

pointing downward: sediment will ollet in the bonnet and sore the stem. $lso: in a line that is subGet to

freeCing temperatures: li


20/28

"ine !ou an install a globe valve with pressure either above the disk or below the disk 2depending on

whih method will be best for the operation: protetion: maintenane: and repair of the mahiner! served

b! the s!stem4: !ou should use aution. The


21/28

*igure 96-.6;alve maintenane hekoff diagram.

spot6in a valve seat: !ou first appl! a thin oating of prussian blue 2ommonl! alled @lue /!kem4 evenl!

over the entire mahined fae surfae of the disk. Insert the disk into the valve and rotate it one6


22/28

"#$PE %& 'E()E*O('$T

*igure 96.6EAamples of spotted6in valve seats.

the disk6seat relationship from time to time so the disk will be moved graduall!: in inrements: through

several rotations. /uring the grinding proess: the grinding ompound will graduall! be displaed from between the seat and disk surfaesD therefore: !ou must stop ever! minute or so to replenish the ompound.

Bhen !ou do this: wipe both the seat and the disk lean before appl!ing the new ompound to the diskfae.

Bhen !ou are satisfied that the irregularities have been removed: spot6in the disk to the seat in the manner

previousl! desribed.

)rinding6in is also used to follow up all mahining work on valve seats or disks. Bhen the valve seat anddisk are first spotted6in after the! have been mahined: the seat ontat will be ver! narrow and will be

loated lose to the bore. )rinding6in: using finer and finer ompounds as the work progresses: auses the

seat ontat to beome broader. The ontat area should be a perfet ring overing about one6third of the

seating surfae.

@e areful to avoid overgrinding a valve seat or disk. Overgrinding will produe a groove in the seating

surfae of the diskD it will also round offH the straight: angular surfae of the disk. 'ahining is the onl! proess b! whih overgrinding an be orreted.

>apping ;alves

Bhen a valve seat ontains irregularities that are slightl! larger than an be satisfatoril! removed b!grinding6in: the irregularities an be removed b! lapping. $ ast6iron tool 2lap4 of eAatl! the same siCe and

shape as the valve disk is used to true the valve seat surfae. The following are some preautions !ou

should follow when lapping valves=

J /o not bear heavil! on the handle of the lap.

J /o not bear sidewa!s on the handle of the lap.

J +hange the relationship between the lap and the valve seat oasionall! so that the lap will graduall! andslowl! rotate around the entire seat irle.

J 3eep a hek on the working surfae of the lap. If a groove develops: have the lap refaed.

J $lwa!s use lean ompound for lapping.


23/28

J (eplae the ompound fre


24/28


25/28

*igure 96,.6@all6float steam trap.

*igure 96, shows a ball6float steam trap. This trap works muh in the same wa! as the buket trap.

+ondensate and steam enter the bod! of the trap: and the ondensate ollets at the bottom. $s theondensate level rises: the ball float rises until it is raised enough to open the outlet valve of the trap. Bhen

the outlet valve opens: the ondensate flows out of the trap into the drain s!stem: and the float level drops:

shutting off the valve until the ondensate level rises again.

@imetalli "team Traps

@imetalli steam traps of the t!pe shown in figure 967 are used in man! ships to drain

*igure 967.6@imetalli steam trap.


26/28

ondensate from main steam lines: auAiliar! steam lines: and other steam omponents. The main working

parts of this steam trap are a segmented bimetalli element and a ball6t!pe hek valve.

The bimetalli element has several bimetalli strips fastened together in a segmented fashion: as shown in

figure 967. One end of the bimetalli element is fastened rigidl! to a part of the valve bod!D the other end:

whih is free to move: is fastened to the top of the stem of the ball6t!pe hek valve.

>ine pressure ating on the hek valve keeps the valve open. Bhen steam enters the trap bod!: the

bimetalli element eApands une


27/28

"team traps that are not operating properl! an ause problems in s!stems and mahiner!. One wa! to

hek on the operation of a steam trap is to listen to it. If the trap is leaking: !ou will probabl! be able to

hear it blowing through. $nother wa! to hek the operation of steam traps is to hek the pressure in the

drain s!stem. $ leaking steam trap auses an unusual inrease in pressure in the drain s!stem. Bhenobserving this ondition: !ou an loate the defetive trap b! utting out 2isolating from the s!stem4 traps:

one at a time: until the pressure in the drain s!stem returns to normal.

?ou should disassemble: lean: and inspet defetive steam traps. $fter determining the ause of the

trouble: repair or replae parts as reTE(" $N/ "T($INE("

*luids are kept lean in a s!stem prinipall! b! devies suh as filters and strainers. 'agneti

*igure 961.6'agneti plugs.

plugs 2fig. 9614 also are used in some strainers to trap iron and steel partiles arried b! fluid. "tudies have

indiated that even partiles as small as to , mirons have a degrading effet: ausing failures andhastening deterioration in man! ases.

There will alwa!s be ontrovers! over the eAat definitions of filters and strainers. In the past: man! suh

devies were named filters but tehniall! lassed as strainers. To minimiCe the ontrovers!: the National

*luid Power $ssoiation gives us these definitions=

*I>TE( 6 $ devie whose primar! funtion is the retention: b! some porous medium: of insolubleontaminants from a fluid.

"T($INE( 6 $ oarse filter.

To put it simpl!: whether the devie is a filter or a strainer: its funtion is to trap ontaminants from fluid

flowing through it. The term porous medium simpl! refers to a sreen or filtering material that allows fluid

flow through it but stops various other materials.

'E"# $N/ 'I+(ON ($TIN)"


28/28

*ilters: whih ma! be made of man! materials other than wire sreen: are rated b! 'I+(ON siCe. $ miron

is 6millionth of a meter or 96millionths of an inh. *or omparison: a grain of salt is about 80 mirons

aross. The smallest partile visible to the naked e!e is about 50 mirons. figure 969 shows the

relationship of

*igure 969.6(elationship of miron siCes.

types of valves-1

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