a wide selection of specialty check valves - ms · pdf file4 the purpose of check valves or...

A Wide Selection of Specialty

Check Valves

Built to MeetTechnical Requirements

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Product development andmanufacturing strictly followthe company’s philosophy of

– uncompromising quality

– robust, well-proven designs

– innovative engineering

– long-term corporatecommitment to quality

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The purpose of check valves or non-return valves isto allow fluid flow in one preferred direction and toprevent backflow, or flow in the opposite direction.As pressure drops in a pipe and the fluid momentumslows, a check valve ideally begins to close. As theflow direction reverses, the check valve closescompletely. Based on this simple operation, itappears that a single check valve design would besufficient for use in any application. In addition to thisbasic non-return function, however, there are otherservice requirements which must be met by a checkvalve design which can vary extensively with differentapplications.

The ADAMS range of check valves is probably themost comprehensive and sophisticated product lineproduced by any manufacturer. Types available rangefrom gravity closing, fast-acting tilting disc valves toultra fast-closing, power assisted check valves forhigh pressure, high temperature applications andultimately to hydraulically damped, combined functioncheck valves for severe pump applications. Our lineof check valves range in sizes from 100 mm / 4 in.to 3000 mm / 120 in.; pressure classes fromPN 2.5 to PN 250 (ANSI 150 to 1500); andtemperatures from -196° C / -320° F to +950° C /+1740° F, depending on the type of valve.

The majority of our check valve designs arefurnished with the exclusive ADAMS inclined conicalseal system. This sealing system, utilized to seat thedisc properly in the closed position, has been usedin thousands of valves, since the 1960’s.During our history we have continually improvedand developed our patented seat technology to theforefront of valve technology. This sealing systemprovides tight shut-off over a wide range of servicetemperatures, freedom from jamming, and low triminertia for faster valve response to flow changes.

The present ADAMS range of check valvesrepresents the result of our years of experience withmanufacturing, development and testing of checkvalves for a wide range of applications. Results ofongoing development and extensive testing will beused for continuous improvement of the currentcheck valve designs to maintain our position ofleading check valve technology.

CONTENTS

Selection diagram ............................................ Page 5

Liquid or gas and steam flow .......................... Page 6

LIQUIDS

Damper controlled closing oruncontrolled closing ......................................... Page 6

Multirate adjustable damping systemFree-acting or positive valve action ................. Page 7

Type GZA ........................................................ Page 8

Type RZN ........................................................ Page 9

Type RZI ........................................................ Page 10

No flow control capability orflow control capability .................................... Page 11

Type GBZ (combined function valve) ............. Page 12Type AZI (combined function valve) ............... Page 13

GASES, STEAM

Gravity closing or assisted closing ................. Page 14Type GMZ ..................................................... Page 15Type SCV ...................................................... Page 16Type FCV ....................................................... Page 17Type MAG ..................................................... Page 18

Conclusion ..................................................... Page 19

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Choosing the Right Valve – Selection Guide

The Selection Diagram below lists all ADAMS check valve types together with selection criteria whichshould provide some assistance in finding the proper check valve type for a specific application.

CHECK VALVES

GASES, STEAMLIQUIDS

UNCONTROLLED

CLOSING

GRAVITY

CLOSING

ASSISTED

CLOSING

TYPE GZA

POSITIVE-VALVE

ACTIONFREE-ACTING TURBINE

COMPRESSOR

BLOWER

COMPRESSOR

BLOWERTURBINE

TYPE AZI

TYPE GBZ

TYPE RZI

TYPE RZN

TYPE MAGPOWER ASSISTE D CLOSING

TYPE FCVPOWER ASSISTE D CLOSING

TYPE SCVPOWER ASSISTE D CLOSING

TYPE GMZ

TYPE MAG GRAVITY CLOSING

TYPE FCVGRAVITY CLOSING

TYPE SCVGRAVITY CLOSING

TYPE MAGGRAVITY CLOSING

DASHPOT

CONTROLLED

CLOSING

WITH FLOW

CONTROL

CAPABILITY

NO FLOW

CONTROL

CAPABILITY

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As shown in the Selection Diagram on page 5, a distinction has been made between liquid and gas or steamflows. The reason for this distinction is as follows:

• The difference in inertia and elasticity of the different fluid types.• The time it takes for the flow velocity to become zero after a pump, compressor or turbine trip. The time until

flow reversal, with gas or steam flows, can go to zero in less than 0.2 seconds in some applications.

LIQUIDS

DAMPER CONTROLLED CLOSING OR UNCONTROLLED CLOSING

Check valves are designed to allow flow in one direction and prevent flow in the opposite direction. Ideally,check valves should begin closing on, or just prior to, pump trip, close slowly with decreasing flow, and closecompletely at zero flow condition.

A check valve without a damping device will beaccelerated in the closing direction when subjectedto backflow and will slam shut, giving rise to highpressures on the downstream side. These pressurechanges are frequently called waterhammer becauseof the sound which often accompanies the pressuresurge.

The rapid and uncontrolled closure of an undampedcheck valve due to flow reversal produces a dynamicimpact load on the disc and body seat. Stressescaused by the impact load can lead to serious damage of valve internals or, in the worst case, those internalsare broken off depending on the magnitude of the impact load and the adequacy of the valve design. Themagnitude of the dynamic impact load depends solely on the velocity of the disc at impact and the inertia ofthe moving valve parts.

Unlike the performance on undamped check valves,the ADAMS range of damped check valves providesthe feature of a controlled closing action on thecessation of forward flow due to the use of a hydraulicdamper. The ADAMS damped check valve can initiallyclose undamped rapidly with decreasing forward flowand will gradually slow the disc closing speed to slowlyreduce the backflow.

This controlled closing action of the damped checkvalve attenuates significantly the magnitude of pressure surge. In addition, the dynamic impact load on thecheck valve is reduced to negligible valve.

Liquid or Gas and Steam Flow

Same installation and service conditions as above. Downstreampressure after closure of ADAMS RZN DN 400 (16”) with damping device

Multi-pump installation. 1 pump in service, 1 pump tripped out.Pressure rise on downstream side after closure of undampened checkvalve of size DN 400 (16”)

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MULTIRATE ADJUSTABLE DAMPING SYSTEM

The hydraulic dampers, as used on ADAMS checkvalves, provide a number of features:

• Closing spring to initiate disc closing acceleration atthe start of flow transient.

• Up to three-stage damping to meet the mostcomplex system requirements.

• Adjustable damping rates to control the disc closingspeed.

All of these features are conveniently accessible fromthe outside for adjustment to tune the check valveperformance during start-up.

It is frequently assumed that the magnitude of pressure surge resultingfrom a rapid check valve closure under reverse flow conditions may onlypresent a problem for low pressure piping systems. However, thepressure surge can easily rise to values that are 10 times the steadystate system pressure. With water as the flowing media in steel piping,the maximum surge pressure is approximately 10 bar (45 psi) for every1 m/s (1 ft/s) change in the flowing velocity. The pressure surge travelsfrom the source of velocity change (the slamming check valve) at thespeed of sound through the piping system. As a result, not only thecheck valve is subjected to the pressure surge but also the entire pipingsystem.

Surge does not originate with the check valve, but it can be magnified by incorrect valve selection or attenuated bythe correct one. Rapid uncontrolled closure of a check valve out of tune with the fluid system can be catastrophic.

FREE-ACTING OR POSITIVE VALVE ACTION

In many applications, it is commonly required that a check valve automatically opens on forward flow andcloses on cessation of flow without any external signal or energy supply. The automatic, or free-actingperformance, of the ADAMS check valve ensures extremely reliable system protection.

The demand for positively operated valves has increased particularly in sizes ranging from 1200 mm (48”) to3000 mm (120”). These valves are usually used on pump discharge lines to function as a check valve. Onpump start-up, the valve is positively moved to full open, and on pump trip, due to receipt of a trip signal, thevalve will close.

The advantage of a positively operated valve, over a free-acting check valve, is the reduced pressure lossacross the valve, due to its full open position, regardless of flow rate, and the streamlined design of the valveinterior. The advantage of a free-acting check valve is the automatic response to flow changes without requiringan external signal or energy supply.

RZN with adjustable damping system

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GZANominal Diameters:500 mm / 20 inchesto 4000 mm / 160 inches

Temperature Range:-20° C / -4° Fto +150° C / +302° F

Pressure Class:PN 2,5/6/10/16/25/40/64ANSI 150/300

Features:– controlled emergency

shut-down valve withtight shut-off and checkvalve function

– hydrodynamically profileddisc

– double eccentric shaft– operation: externally located

closing weight and hydraulicservo-actuator

Advantages:– low flow loss coefficients– maintenance friendly design– tailored design with extensive

accessories

Options:– back-up seal for maintenance– multirate adjustable interval

damping system– hydraulic operation– electronic control systems– overspeed detector– orifice plates– disc locking device, mansafe

design– vulcanized hard rubber

coating– butt weld ends

The design of GZA valves utilizesthe type OSK tight shut-off valveas the basis, and an external leverand closing weight with ahydraulic cylinder.The valves are usually suppliedwith a hydraulic power unit whichcan be fitted to the valve as acompact, self-contained unit.

On pump start-up, the valve is positively opened and remains in the full openposition during normal service due to hydraulic pressure applied to the externalhydraulic cylinder. On pump trip, the valve is also tripped to close on its ownaccord by means of the lever and closing weight. As the valve closes, thehydraulic cylinder is used as a damping device providing two- or three-stagemultirate adjustable and controlled closing action.

Use of multiple valves and sensors, which initiate the trip action, can increasethe system redundancy to ensure the safety aspects of the valve performance.The trip signal can be either hydraulic or electric.

GZA valves are frequently used in power plant applications to reliably protectlarge pumps in the cooling water system against reverse flow.

Pipe Break Safety Device, Turbine Protection, PumpProtection

Emergency shut down valve 3650 mm / 144 inches for ahydroelectric power unit

Hydraulic cylinder for a hydroelectric powerunit

GZU

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This fast-acting, tilting disc checkvalve, with low inertia, ensures quickvalve response to liquid flow changes.The triple eccentrically mounted discprovides maximum hydro-dynamicperformance for low pressure lossand freedom from jamming and flutter.If water hammer is the prime concern,the closure speed can be adjusted tomeet the system requirements. This isalso important for the long termflexibility of plant operations. Even iffuture piping or system changes aremade, the valve can always beadjusted to match the new set ofsystem characteristics.

The ADAMS inclined conical seal system ensuresthat shut-off against reverse flow is tight and progressive

The RZN is an ultra-reliable, non-slam check valve

The RZN uses a multirate adjustabledamping system

The RZN type check valve, withits multirate adjustable dampingsystem, offers complete primaryprotection in even the mostadverse applications. The compactdesign allows installation in veryconfined spaces.

RZN-sealing systems: Laminated metal-to metal or resilient seal

RZNNominal Diameters:150 mm / 6 inchesto 1000 mm / 40 inches

Temperature Range:-50° C / -58° Fto +200° C / + 392° F

Pressure Class:PN 10/16/25/40/64ANSI 150/300/600

Features:– non-return valve with

controlled, non-slam closure– resilient seal or laminated

metal-to-metal seal– triple offset design with

inclined conical sealingsystem

– adjustable hydraulic dampingsystem, located externally andseparated from the media

Advantages:– complete pump protection– low flow loss– progressive sealing system– axial pressure balanced shaft

seals for low friction– auto-closing– damper adjustment locking– additional screw safety device– prepared for retro-fitting of

counterweights if flowconditions change

Options:– damping system for opening– flow control valves– disc locking device, mansafe

design– additional counterweight– vulcanized hard rubber


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Nominal Diameters:500 mm / 20 inchesto 3000 mm / 120 inches


Pressure Class:PN 2,5/6/10/16/25/40ANSI 150/300

Features:– non-return valve with

multi-rate adjustable intervaldamping system

– resilient seal or laminatedmetal-to-metal seal

– triple offset design withinclined conical sealingsystem

– three adjustableindependent damping rates

– auto-closing– damper adjustment locking

Advantages:– controlled non-slam closure– adjustable closing

characteristic– additional screw safety

device– prepared for retro-fitting of

counterweights, if flowconditions change

– longevity, even for frequentcycle operation

Options:– damping system for opening– pneumatic or hydraulic

power pack for positiveoperation

– disc locking device, mansafedesign

– additional counterweight– vulcanized hard rubber


A multirate, adjustable interval damping system provides the optimum controlover surge in large diameter pipelines. The RZI provides adjustment for eachdamping rate and also the timing of rate increased during check valve closure.This means that a damping sequence can be tuned to precisely match theclosing characteristic required by a pump installation in order to avert anexcessive water hammer.

RZIThe RZI is essentially thesame basic designconfiguration as the RZNexcept for its more advanceddamping system which issetting new standards insurge control. Using ADAMSexclusive multirate adjustableinterval damping system, theRZI provides the optimumcontrol over surge in liquidtransmission lines. In additionto providing speedadjustment for each of threeseparate damping rate

increments, the point during the check valve closing travel at which each ratechange occurs is completely adjustable. This means that the RZI can be tunedto exactly match the closing characteristics required in a pump installation toprevent excessive pressure surge.

By turning flow control valves on the damping cylinder, the disc closing speed can be adjusted. Bymoving the trigger lever, the point of disc travel on which flow control valves are triggered, can bechanged

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AZI (pictured here with a hydraulic unit) and GBZ are both examples of ADAMScombined check and tight shut-off valves

Combined Check ValveFeatures:

– Installation space and costssavings

– Reduction in pressure loss– Flow control capability

together with the prioritycheck valve function

– Possible use as a drain valve– Lost motion coupling ensures

priority function as a checkvalve so that the valveauto-closes from any position

NO FLOW CONTROL CAPABILITY OR FLOW CONTROLCAPABILITY

The conventional check valve generally provides no capability for flow controland is solely utilized for the check valve function.

In many applications, however, the check valve is installed in the piping systemin series with a shut-off valve. Check valves need five times the nominaldiameter piping space down stream before an additional valve is placed intoservice. This means extra weight, length and more supports and hangers arenecessary. A check valve, with additional gate valve, requires four flanges, fourgaskets and four sets of bolting. A combination shut-off and check onlyrequires two sets of each. It is, therefore, a reasonable idea to combine thefunctions of the two valves in a single valve.

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Features:– 3 in 1 combination valve for

tight shut-off, control andnon-return function in onecompact unit

– resilient seal or laminatedmetal-to-metal sealing


– auto-closing– minimum pressure loss in

open position– multirate adjustable damping

system, located externallyand separated from themedia

Advantages:– multi-function– compact design– minimum pressure loss– stable operation– controlled, non-slam closure– additional screw safety

device– prepared for retro-fitting of


Options:– wide choice of actuators

and control systems– disc locking device, mansafe



This combination stop and checkvalve combines tight shut-off, flowcontrol and check valve functions in asingle compact unit. Like the typeMAG, RZN and RZI designs, a fast-acting, tilting disc check valve is usedas the basis for the GBZ design. TheGBZ is fitted with a compact gearboxwhich contains the reduction gear,lost motion coupling and a hydraulicdamping unit. The lost motioncoupling ensures priority function as acheck valve so that the valve canauto-close from any partial or fullopen position. Throttling of the valve,which can be achieved by turning thehandwheel, can be quite useful forfilling a piping system during start-up

The integral, hydraulic damping cylinder provides multi-rate adjustable dampingfor controlled and non-slam closure to cope with arduous system requirements.Since the GBZ can replace two conventional valves, there are a number of savingssuch as less weight, less space, lower installation costs and low pressure loss.

These features make the GBZ ideally suited for installation on pump dischargelines.

Stop and Check in one valve made possible by lost-motion coupling

GBZ

or after an outage. Additionally, the valve disc can be locked in full openposition by turning the handwheel to drain a piping system. The handwheel caneven be replaced in the field with an electric actuator for automated remoteoperation.

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The function of the AZI isidentical to that of thetype GBZ combinationstop and check valve.However, the AZI extendsthe range of applicationsbecause of its availabilityin larger sizes and higherpressure ratings. Insteadof a single gearbox usedon the GBZ, the AZI isfitted with a hydraulicdamping unit on one sideand a gearbox with anintegral lost motion

AZI-AGF with gearbox/handwheel and hydraulic damping cylinder

The AZI is a beneficial choice for every installation calling for the application ofa shut-off valve and a non-slam check valve in larger sizes or higher pressuresthan the GBZ was designed for.

AZI-AGF (On the left side, two options for operation -either a gearbox and handwheel or an electric actuator.Hydraulic damping cylinder, on the right)




Features:– 3 in 1 combination valve for

tight shut-off, control andnon-return function in onecompact unit

– resilient seal or laminatedmetal-to-metal sealing


– auto-closing– minimum pressure loss in

open position– multirate adjustable interval

damping system

Advantages:– multifunction– compact design– minimum pressure loss– stable operation– controlled, non-slam closure– additional screw safety device– prepared for retro-fitting of


Options:– wide choice of actuators and

control systems– disc locking device, mansafe


coating– butt weld ends– complete hydraulic unit

AZI

coupling on the other. The hydraulic damping unit provides optimum controlover surge pressure in liquid piping systems. Fully adjustable dampingincrements in conjunction with adjustable damping strokes ensure a fullycontrolled and non-slam closing action.

The gearbox, including a lost motion coupling, provides flow control andautomatic check valve function which can be very beneficial for filling a pipingsystem. The handwheel at the gearbox can easily be replaced with an electricactuator for remote operation. As an alternative, the AZI gearbox can bereplaced with a hydraulic power unit which permits the use of the hydraulicdamping cylinder for positive valve operation.

The AZI is manufactured in two basic designs:

AZI-VHS (On the left side, the hydraulicactuator with damping function, connectedto a hydraulic unit. On the right, an optionalmounting of lever and weight)

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For the protection of rotary equipment such as compressors and turbinesagainst reverse flow, it is sometimes suitable to utilize check valves whereclosing is achieved just by gravity. These valves are usually identified asnon-critical check valves.

When protection of valuable rotary equipment against reverse flow is of criticalimportance, check valve designs are available as combined function or powerassisted closing check valves where some method of positive actuation isadded to the basic auto-closing valve. These power assisted closing actuators,fitted to the check valves, overcome increased inherent valve friction cause byany deposits or wear due to frequent cycling. They are providing a backupprotection for rotating equipment because they are forcing valve closure in theevent the check valve should fail to auto-close on cessation of flow.

Positively assisted closing action is frequently required for check valves utilizedon large compressor discharge lines and on steam extraction lines to heaterswhere a large amount of energy is stored in the specific extraction system.Methods of actuation include double-acting pneumatic or hydraulic cylinderswith options of spring return or accumulator stored energy systems.

Another feature of the power assisted closing actuators is the optional provisionfor on-load exercising, a test procedure which is widely used with check valvesinstalled in steam extraction lines from turbines. The actuator is periodicallytripped (sometimes daily), and as the valve disc is momentarily forced farenough closed to demonstrate that the check valve operates freely and returnsto its initial operating position after actuation force is removed. On-load testingcan be performed locally or remotely.

Adams check valves suitable for gasor steam applications: GMZ, SCV,FCV and MAG

GASES, STEAM

GRAVITY CLOSING OR POWER ASSISTED CLOSING

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The ADAMS type GMZ assistednon-slam check valve isdesigned for gas systems whereultra-reliable, high-integrityoperation is required. The basicdisc element is a fast acting,tilting disc check valve withstable flow response. Discmovement is controlled by alever, an adjustable closingweight and a light hydraulicdamper to prevent slam or discoscillation. Assisted closing isprovided by a single-actingpneumatic cylinder connected tothe lever arm by a clevis. Thepneumatic actuator is controlledby a solenoid valve whichpermits tripping for positively

GMZ with pneumatic closing actuator, solenoid valve andhydraulic damping system



Pressure Class:PN 10/16/25/40ANSI 150/300

Features:– power assisted, compressor

check valve– resilient seal or laminated

metal-to-metal seal– triple offset design with


– positive closure via springloaded pneumatic actuator

– adjustable closing weight– adjustable hydraulic damping

system

Advantages:– stable operation during flow

transients– capable of varying the

pressure loss with closingweight adjustment

– axial pressure balanced shaftseals for low friction

– additional screw safety device– long service life

Options:– controlled, compulsory closure

via pneumatic or spring-assisted actuator

– heating jacket– accessories for remote control– butt weld ends

GMZ

assisted closure with either a de-energized or energized state. The solenoidvalve is normally operated through a compressor start-up and shut-downsignal.

In normal GMZ operation, the disc is opened by forward flow to a positionwhere flow and gravity forces are balanced. With loss of forward flow, the GMZwill auto-close as the hydraulic damper permits smooth non-slam closure. Inaddition, normal shut-down procedure is initiated by a signal to the solenoidvalve to start pneumatic assisted closure prior to cessation of the forward flow.

Special options and accessories available include air open / spring closeactuators, steam jacketing, limit switches and position transmitter for remoteindicate of disc position.

The type GMZ check valve is particularly suitable for installations in gassystems and widely used on compressor discharge lines.

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Temperature Range:steam up to 550° C / 1025° F

Pressure Class:PN 2,5/6/10/16/25/40/64/100ANSI 150/300/600

Features:– gravity closing– chromium steel disc plate– stainless steel seat, fully

integrated to the valve bodyseat

– operation: free swinging orwith pneumatic closingassistance

Advantages:– ANSI / FCI 70-2 Cl. V tight

shut-off– anti-blowout shaft design– no sealing friction– no packing friction– low pressure loss by lost

motion coupling– high temperature

compatibility– inherently fire-safe– low operation torques– compact, robust

construction– low maintenance– top entry mounting port– field repairable

Options:– free-swinging design– pneumatic spring return

actuator as closingassistance

– welding flanges– duct for condense water

release– operation: pneumatic

closing assisted

The ADAMS SCV check valvesare designed for installation on theoutlet side of steam turbines.These fast-closing, non-returnvalves protect the turbine from theback flow of steam or water,which may severely damage theturbine blades.

The free-swinging SCV design closes bygravity. A pneumatic actuator is standardfor power assisted closing. Thisconfiguration features a two-piece shaftdesign connected by a free-travel clutch(lost motion coupling). The free-travelclutch is only engaged in the event ofactuator closing. This design alsoeliminates frictional losses caused by thepacking and does not increase thepressure loss.

Even after installation, the actuator maybe mounted to the other side.

The standard SCV designfeatures butt weld ends. Flangedend valves are also available.

The entire disc is made of chromium steel to reduce abrasive effects.

SCV

SCV with a pneumatic actuator for assisted closing

SCV Body during ISO Certification on the 3Dmeasuring machine

The top entry mounting port allows discreplacement without removing the valve fromthe line.

The stainless steel inlayed seat is welded onthe body and meets Class V tightness.

The SCV is thoroughly designed on a 3D-CADsystem.

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The FCV is a robust valve withlow inertia moving parts designedto withstand very fast closurewith complete reliability. Theinclined tilting disc designensures inherent gravity closure,stable operation, low pressureloss and fast response.



Pressure Class:PN 16/25/40/64/100/160/250ANSI 300/600/900/1500

Features:– ultra fast-closing, non-return

valve– triple offset design with


– optimum flow openingcharacteristics

– inherent gravity closure– low inertia– all parts designed to tolerate

high impact– fast response– butt weld ends

(body length ISO F5)

Advantages:– robust forged steel

construction– excellent sealing

characteristics at high and lowoperating pressure

– short closing travel– absorption of high dynamic

forces– freedom from jamming at seat– low friction– no internal screw connections– field replaceable disc– minimum maintenance– reliable operational function

Options:– inspection/mounting port– internal steam heating– accessories for remote control– flanged design– power assisted:

pneumatic, hydraulic orspring return actuator

FCV with gravity closing assistance

Closing time of a FCV of 450 mm (18") size, class 300in free air

FCV with spring return pneumaticactuator as closing assistance

FCV

On loss of load, large steam turbinescan rapidly accelerate to overspeeddue to reverse steam flow caused bythe energy contained in theextraction and feedwater heatersystem. Flow reversal can occur inless than 0.2 seconds and this cancause very high impact loads oncheck valve closure if delayed. Thisnecessitates the special designfeatures of the type FCV.

The FCV is designed to respond as rapidly aspossible by means of low inertia components,optimum closing moment and minimumfriction.

The type FCV has achieved an enviable recordof reliability over long periods of services withvery low maintenance, even in units withnumerous shut-downs. The FCV, with gravityclosing, is particularly designed for use onsteam extraction lines to protect turbinesagainst overspeed and partial water inductionon load rejection.

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MAGNominal Diameters:100 mm / 4 inchesto 2000 mm / 80 inches

Temperature Range:-50° C / -58°Fto 500° C / 932° F

Pressure Class:PN 6/10/16/25/40ANSI 150/300

Features:– quick-closing check valve

with internal balance weightin a pressurized externalhousing

– laminated metal-to-metalsealing


– opened by flow– auto-closing– fast-response at low

differential pressure

Advantages:– excellent sealing

characteristics– low pressure loss coefficients– axial pressure balanced shaft

seals for low friction– additional screw safety

device– robust construction– minimum maintenance

Options:– manual or electrical override– pneumatic or hydraulic

actuator– steam purge at seat– heating jacket– butt weld ends

MAG with gravity closing

MAG with power assisted closing

The ADAMS type MAGhas been speciallydesigned anddeveloped for lowpressure gas / steamservice to protectsteam turbines andcompressors from theeffects of reversal ofgas / steam flow ontrip or emergencyshut-down. Its mainfeatures are ultra-reliable fast closure,

tight shut-off, low pressure loss and the ability to with-stand a large number ofcycles without failure.

The MAG is a gravity closing tilting disc check valve opened by gas /steam flow and designed to close rapidly just prior to flow reversal. The disc isprofiled to improve aerodynamic lift, and the closing weight partially balancesthe disc weight in any open position to minimize pressure loss. The pressurizedweight chamber out of the flow stream to avoid the friction of a shaft seal andto further enhance reliability and reduce flow disturbance. The weight chamberis provided with adequate drains to eliminate problems with condensate or dirtbuild-up and is accessible for maintenance.

The MAG is also available with an actuator for positively assisted closure,which operates via lost motion coupling on the valve shaft. The coupling iscontained in the weight chamber to ensure that shaft seal friction is notaffecting the valve performance. Actuation can be either manual, electric,hydraulic or pneumatic.

The MAG is generally used on large, low pressure steam extraction lines eitherwith or without power assisted closure as specified. Another application of theMAG is for use on process gas lines to protect large cracking furnaces againstflow reversal during the switch-over procedure or due to a tube rupture in thefurnace.

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CONCLUSION

The check valve types, as presented in thisbrochure, are available in a wide range of sizes,pressure ratings and materials. In addition, manyspecial construction features and variousaccessories can be supplied to meet requirementsfor specific applications.

The foregoing discussion, together with theSelection Diagram, lists the most common check valveapplications. There are many special options anddesigns which cannot be covered in a briefguide like this. ADAMS produces many specialvalves (air admission, line break, emergencyshut-down, etc.) some of which utilize check valvefeatures. Leaflets giving detailed data on specialapplications are available on request.

When specifying check valves for major projects,it is advisable to consult your nearest ADAMS salesoffice or representative for specific information andadvice.

Thank you for considering ADAMS.

ADAMS Armaturen GmbHBaukauer Strasse 55D-44653 HernePhone +49 - (0) - 2323 2090Fax +49 - (0) - 2323 209286Internet: www.adams-armaturen.deE-Mail: [email protected]

ADAMS Schweiz AGBadstrasse 11CH-7249 Klosters-SerneusPhone +41 - (0) - 81 4102222Fax +41 - (0) - 81 4102229Internet: www.adamsarmaturen.chE-Mail: [email protected]

ADAMS Valves Inc.10649 Haddington Dr. No. 160Houston, Texas 77043 U.S.A.Phone +1 - (713) - 973-2490Fax +1 - (713) - 973-2788Internet: www.adamsvalves-usa.comE-Mail: [email protected]

Since 1960, ADAMS‘ valves havebeen internationally proven acclaimedin all major industries and services.

The ADAMS name is synonymous withuncompromising quality.

Today, the ADAMS group hasmanufacturing facilities in Germany,Switzerland and the United States andmultiple sales offices with authorizedagents on every continent.

This widespread network assuresoptimum service to all customers.

To find your local sales agent pleaselog onto one of our websites orcontact one of the offices above.

a wide selection of specialty check valves - ms · pdf file4 the purpose of check valves or...

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