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surfaces. To accomplish self cleaning, the stopper is typically not conical. A circular recess in a weight that fits over a matching narrow ridge at the rim of an orifice is a common design. The application inherently tolerates a modest reverse leakage rate, a perfect seal is not required. A flow check has an operating screw to allow the valve to be held open, the opposite of the control on a stop-check valve, as an aide for filling the system and for purging air from the system.
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engines as the air intake valve for the crankcase volume and in air compressors as both intake and exhaust valves for the cylinder(s). Although reed valves are typically used for gasses rather than liquids, the
Autotrol brand of water treatment control valves are designed as a set of reed valves taking advantage of the sealing characteristic, selectively forcing open some of the reeds to establish a flow path.
134:
452:, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow.
382:, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can come in various sizes, large check valves are often swing check valves. A common issue caused by swing check valves is known as
600:. The water to the slide flows through a pipe which doubles as the tower holding the steps to the slide. When the facility with the slide closes for the night, the check valve stops the flow of water through the pipe; when the facility reopens for the next day, the valve is opened and the flow restarts, making the slide ready for use again.
386:. This can occur when the swing check closes and the flow abruptly stops, causing a surge of pressure resulting in high velocity shock waves that act against the piping and valves, placing large stress on the metals and vibrations in the system. Undetected, water hammer can rupture pumps, valves, and pipes within the system.
286:-loaded to help keep it shut. For those designs without a spring, reverse flow is required to move the ball toward the seat and create a seal. The interior surface of the main seats of ball check valves are more or less conically tapered to guide the ball into the seat and form a positive seal when stopping reverse flow.
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is a check valve formed by a flexible flat sheet that seals an orifice plate. The cracking pressure is very low, the moving part has low mass allowing rapid operation, the flow resistance is moderate, and the seal improves with back pressure. These are commonly found in two stroke internal combustion
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A stop-check valve is a check valve with override control to stop flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behavior), it can also be deliberately shut by an external mechanism, thereby preventing
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Check valves are also often used when multiple gases are mixed into one gas stream. A check valve is installed on each of the individual gas streams to prevent mixing of the gases in the original source. For example, if a fuel and an oxidizer are to be mixed, then check valves will normally be used
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Pneumatic non-return valves provide the ability to lock the valve, hence preventing flow in either direction. This may be used if for example a site with hazardous materials should be protected from flood water, however it is also important that the materials can’t leak, for example during transfer
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An in-line check valve is a check valve similar to the lift check valve. However, this valve generally has a spring that will 'lift' when there is pressure on the upstream side of the valve. The pressure needed on the upstream side of the valve to overcome the spring tension is called the 'cracking
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and seats made of sapphire or both ball and seat of ruby, for both hardness and chemical resistance. After prolonged use, such check valves can eventually wear out or the seat can develop a crack, requiring replacement. Therefore, such valves are made to be replaceable, sometimes placed in a small
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Typical applications in the nuclear industry are feed water control systems, dump lines, make-up water, miscellaneous process systems, N2 systems, and monitoring and sampling systems. In aircraft and aerospace, check valves are used where high vibration, large temperature extremes and corrosive
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and cooling systems to prevent unwanted passive gravity flow. A flow check is a simple flow lifted gravity closed heavy metal stopper designed for low flow resistance, many decades of continuous service, and to self-clean the fine particulates commonly found in hydronic systems from the sealing
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A diaphragm check valve uses a flexing rubber diaphragm positioned to create a normally-closed valve. Pressure on the upstream side must be greater than the pressure on the downstream side by a certain amount, known as the pressure differential, for the check valve to open allowing flow. Once
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to leave. There are various types of check valves used in a wide variety of applications. Check valves are often part of common household items. Although they are available in a wide range of sizes and costs, check valves generally are very small, simple, and inexpensive. Check valves work
411:(for sanitary drainage system) that protects against flooding caused by return flow of sewage waters. Such risk occurs most often in sanitary drainage systems connected to combined sewerage systems and in rainwater drainage systems. It may be caused by intense rainfall, thaw or flood.
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commonly use inlet and outlet ball check valves. These valves often look like small cylinders attached to the pump head on the inlet and outlet lines. Many similar pump-like mechanisms for moving volumes of fluids around use check valves such as ball check valves. The
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Refers to the pressure differential between the inlet and outlet of the valve during the closing process of the check valve, at which there is no visible leak rate. Reseal pressure is also known as sealing pressure, seating head (pressure) or closing
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Refers to the minimum pressure differential needed between the inlet and outlet of the valve at which the first indication of flow occurs (steady stream of bubbles). Cracking pressure is also known as unseating head (pressure) or opening
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is an example of this type of valve. Tank pressure holding it closed is overcome by manual lift of the flapper. It then remains open until the tank drains and the flapper falls due to gravity. Another variation of this mechanism is the
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In 2010, NASA's Jet
Propulsion Laboratory slightly modified a simple check valve design with the intention to store liquid samples indicative to life on Mars in separate reservoirs of the device without fear of cross contamination.
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in which there are two ball/seat combinations sequentially in the same body to ensure positive leak-tight shutoff when blocking reverse flow; and piston check valves, wafer check valves, and ball-and-cone check valves.
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which is the minimum differential upstream pressure between inlet and outlet at which the valve will operate. Typically the check valve is designed for and can therefore be specified for a specific cracking pressure.
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and fire life safety systems. A hinged gate only remains open in the inflowing direction. The clapper valve often also has a spring that keeps the gate shut when there is no forward pressure. Another example is the
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Ball check valves are often very small, simple, and cheap. They are commonly used in liquid or gel minipump dispenser spigots, spray devices, some rubber bulbs for pumping air, etc., manual air pumps and some other
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automatically and most are not controlled by a person or any external control; accordingly, most do not have any valve handle or stem. The bodies (external shells) of most check valves are made of plastic or metal.
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294:, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials; in some specialized cases out of highly durable or inert materials, such as
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fluids are present. For example, spacecraft and launch vehicle propulsion propellant control for reaction control systems (RCS) and
Attitude Control Systems (ACS) and aircraft hydraulic systems.
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developed a "simple self sealing check valve, adapted to be connected in the pipe connections without requiring special fittings and which may be readily opened for inspection or repair" 1907 (
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systems that are plumbed into the main water supply of a utility provider may be required to have one or more check valves fitted to prevent contamination of the primary supply by rainwater.
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A butterfly check valve is a variant on the swing check valve, having two hinged flaps which act as check valves to prevent backwards flow. It should not be confused with the similarly named
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pressure'. When the pressure going through the valve goes below the cracking pressure, the spring will close the valve to prevent back-flow in the process.
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The operation, benefits, applications and selection of different designs, including lift, disc, swing and wafer check valves are explained in this tutorial
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is a check valve in which flow proceeds through a soft tube that protrudes into the downstream side. Back-pressure collapses this tube, cutting off flow.
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A ball check valve is a check valve in which the closing member, the movable part to block the flow, is a ball. In some ball check valves, the ball is
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A swing check valve (or tilting disc check valve) is a check valve in which the disc, the movable part to block the flow, swings on a
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682:, such as toys, mattresses and boats. This allows the object to be inflated without continuous or uninterrupted air pressure.
333:, which are a different type of valve in which a ball rotating on a pin acts as a controllable rotor to stop or direct flow.
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on both the fuel and oxidizer sources to ensure that the original gas cylinders remain pure and therefore nonflammable.
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positive pressure stops, the diaphragm automatically flexes back to its original closed position. This type is used in
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and similar high pressure applications commonly use small inlet and outlet ball check valves with balls of (artificial)
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Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for
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The check valves on this steam locomotive are located under the small cover between the chimney and the main dome.
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emitters have small check valves built into them to keep the lines from draining when the system is shut off.
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Check valves used in domestic heating systems to prevent vertical convection, especially in combination with
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When a sanitary potable water supply is plumbed to an unsanitary system, for example lawn sprinklers, a
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A ball check valve in the open position to allow forward flow and closed position to block reverse flow
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There are similar check valves where the disc is not a ball, but some other shape, such as a
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1109:"Industrial valve store>>Valves>>Check Valves, paragraph on ball check valves"
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Hydraulic jacks use ball check valves to build pressure on the lifting side of the jack.
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a pressure higher at the outlet of a fitting than that at the inlet or a point upstream
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is used to prevent contaminated water from re-entering the domestic water supply.
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1087:"Chromatography on line, from J.W. Dolan, LCGC North Am. 26(6), 532–538 (2008)"
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1370:– n.b. the test protocol did not match the conditions described in the patent)
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which can withstand high pressure and which is screwed into the pump head.
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A lift-check valve is a check valve in which the disc, sometimes called a
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invented a deceptively simple one-way valve for fluids in 1916, called a
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Check valves are often used with some types of pumps. Piston-driven and
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energized by a spring. Ball check valves should not be confused with
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Multiple check valves can be connected in series. For example, a
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Disc for an alloy check valve also known as axial check valve
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This
Siamese clappered inlet allows one or two inputs into a
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Check valves are used in many fluid systems such as those in
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Check valves are also used in the pumps that supply water to
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ValveMan Brand VM6800 In-Line Check Valve- Product
Overview
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1358:, a scaled down version of Tesla's original fluidic diode.
1320:. NASA's Jet Propulsion Laboratory, Pasadena, California.
968:(3rd ed.). Oxford, UK: Elsevier Advanced Technology.
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Flanged nozzle inconel check valve or axial check valve
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An important concept in check valves is the cracking
593:are fitted with check valves to prevent back-flow.
49:. Unsourced material may be challenged and removed.
1259:"Nuclear Check Valves – Excess Flow Check Valves"
804:Inside hastelloy check valve, wafer configuration
764:Inside view of a tilting disc inconel check valve
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1368:a test of a design showing very poor performance
666:installations, also are called gravity brakes.
1315:"Simple Check Valves for Microfluidic Devices"
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1050:"NIBCO® Chemtrol® TruUnion Ball Check Valves"
1031:"GF PVC Cone Check Valves Type 561 & 562"
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1278:"Aircraft Check Valves in Hydraulic Systems"
996:: CS1 maint: multiple names: authors list (
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530:to keep potentially contaminated water from
423:Large butterfly check valve for a water pump
193:) to flow through it in only one direction.
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310:plastic body tightly fitted inside a metal
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616:, and in many other industrial processes.
440:any flow regardless of forward pressure.
109:Learn how and when to remove this message
1345:Working Principle of Spring Check Valves
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966:Valves, piping, and pipelines handbook
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300:High-performance liquid chromatography
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1374:Check Valve Installation and Benefits
1356:A picture of a microscopic checkvalve
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370:Swing check valve opening and closing
141:. The arrow shows the flow direction.
964:Christopher., Dickenson, T. (1999).
816:Large carbon steel swing check valve
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47:adding citations to reliable sources
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1126:. Northvale Korting. Archived from
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139:piping and instrumentation diagrams
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1366:, Tesla's original fluidic diode (
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678:Check valves are commonly used in
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740:Stainless steel wafer check valve
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321:A disassembled poppet check valve
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402:, used in applications such
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1421:Backflow prevention methods
1295:Valcor Aerospace Division.
1085:Dolan, John (20 May 2016).
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707:. It was patented in 1920 (
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1428:Atmospheric vacuum breaker
1124:"Norval valve performance"
1093:. LCGC Europe-05-01-2016.
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528:backflow prevention device
483:pneumatic non-return valve
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477:Pneumatic non-return valve
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644:, a check valve called a
149:Vertical lift check valve
1297:"Aerospace Check Valves"
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544:double ball check valves
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1494:Steam boiler components
1458:Pressure vacuum breaker
1240:"How Water Slides Work"
1499:Firefighting equipment
728:Hastelloy check valves
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395:flush-toilet mechanism
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1350:Check Valves Tutorial
1208:pentairaquaeurope.com
709:U.S. patent 1,329,559
653:irrigation sprinklers
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415:Butterfly check valve
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346:(face masks) with an
337:Diaphragm check valve
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213:Technical terminology
181:that normally allows
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866:Helium release valve
670:Rainwater harvesting
604:Industrial processes
43:improve this article
1363:US Patent 1,329,559
1222:"Flow Check Valves"
1172:Fleming, Jennifer.
1048:U.S. Plastic Corp.
1029:U.S. Plastic Corp.
852:Plastic Check Valve
752:Inconel check valve
695:U.S. patent 865,631
526:is often used as a
456:In-line check valve
16:Flow control device
1448:Double check valve
646:backflow preventer
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1246:. 31 August 2001.
1244:howstuffworks.com
1122:Wright, Stephen.
1054:www.usplastic.com
1035:www.usplastic.com
889:electrical analog
870:Rolex Sea-Dweller
840:Wafer check valve
542:. There are also
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218:Cracking pressure
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60: –
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58:"Check valve"
55:
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32:This article
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632:Domestic use
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551:Applications
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99:October 2017
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41:Please help
36:verification
33:
1438:Check valve
1091:LCGC Europe
945:Tesla valve
930:Globe valve
864:Integrated
705:Tesla valve
680:inflatables
638:dish washer
344:respirators
331:ball valves
155:check valve
129:check valve
1483:Categories
1414:prevention
1328:2017-10-26
1301:valcor.com
1282:valcor.com
1263:valcor.com
1204:"Autotrol"
1158:2017-10-26
1153:DFT Valves
1134:2009-05-19
952:References
925:Gate valve
910:Ball valve
905:Reed valve
790:deluge gun
583:feed pumps
534:back into
505:Flow check
498:reed valve
492:Reed valve
171:foot valve
69:newspapers
1068:"NEOPERL"
1012:"NEOPERL"
992:cite book
587:injectors
536:municipal
532:siphoning
231:pressure.
222:pressure.
1410:Backflow
1276:Valcor.
1188:1 August
984:41137607
895:Top feed
878:See also
610:chemical
572:such as
380:trunnion
296:sapphire
206:pressure
1433:Air gap
686:History
591:boilers
312:fitting
127:inconel
83:scholar
1504:Valves
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715:Images
538:water
327:poppet
284:spring
187:liquid
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640:or a
556:Pumps
393:in a
376:hinge
303:pumps
292:pumps
244:Types
198:fluid
183:fluid
179:valve
177:is a
173:, or
90:JSTOR
76:books
1412:and
1190:2012
998:link
980:OCLC
970:ISBN
655:and
612:and
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389:The
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