一方向弁

関: unidirectional valve

WordNet

to a great degree or by a great distance; very much (`right smart is regional in the United States); "way over budget"; "way off base"; "the other side of the hill is right smart steeper than the side we are on" (同)right_smart
a portion of something divided into shares; "they split the loot three ways"
the condition of things generally; "thats the way it is"; "I felt the same way"
a course of conduct; "the path of virtue"; "we went our separate ways"; "our paths in life led us apart"; "genius usually follows a revolutionary path" (同)path, way of life
a journey or passage; "they are on the way"
any artifact consisting of a road or path affording passage from one place to another; "he said he was looking for the way out"
the property of distance in general; "its a long way to Moscow"; "he went a long ways"
a general category of things; used in the expression `in the way of; "they didnt have much in the way of clothing"
doing as one pleases or chooses; "if I had my way"
used informally as an intensifier; "that is one fine dog"
the smallest whole number or a numeral representing this number; "he has the one but will need a two and three to go with it"; "they had lunch at one" (同)1, I, ace, single, unity
a single person or thing; "he is the best one"; "this is the one I ordered"
used of a single unit or thing; not two or more; "`ane is Scottish" (同)1, i, ane
having the indivisible character of a unit; "a unitary action"; "spoke with one voice" (同)unitary
being a single entity made by combining separate components; "three chemicals combining into one solution"
indefinite in time or position; "he will come one day"; "one place or another"
of the same kind or quality; "two animals of one species"
indicates continuity or persistence or concentration; "his spirit lives on"; "shall I read on?"
(of events) planned or scheduled; "the picnic is on, rain or shine"; "we have nothing on for Friday night"
in a state required for something to function or be effective; "turn the lights on"; "get a load on"
in operation or operational; "left the oven on"; "the switch is in the on position"
control consisting of a mechanical device for controlling the flow of a fluid
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
one of the paired hinged shells of certain molluscs and of brachiopods
the entire one-piece shell of a snail and certain other molluscs
a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it
structure consisting of a sloping way down to the water from the place where ships are built or repaired (同)shipway, slipway

PrepTutorEJDIC

〈C〉(…へ向かう)『道』,通り道;(…への)道筋《+to+名》 / 〈C〉『方向』,方角 / 〈U〉道を進むこと,進行,前進 / 〈U〉《しばしば a way》距離,道程 / 〈U〉《しばしば形容詞とともに》『やり方』,方法,手段 / 〈C〉特有なやり方,流儀,癖 / 〈U〉《しばしば複数形で》《単数扱い》習慣,風習,しきたり / 〈C〉《in…way[s]の形で》(…の)点(箇所)で / 〈U〉《しばしば a way》(特に健康の)ぐあい,様子 / 〈C〉経験の及ぶ範囲;人生(行動,経験)の道 / 通行権(the right of way)
はるかに,大いに,ずっと
『1個の』,一人の,単一の;《補語にのみ用いて》1歳の / 《時を表す名詞と共に》『ある』… / 《人名に付けて》…という[名の]人 / 同一の,同じ(the same) / 《theまたは所有格を付けて》たった一つの,唯一の / 《another, [the]otherと対比して》一方の / 〈U〉〈C〉『1つ』,1個,一人,1時,1歳 / 〈C〉(数字の)『1』;1の記号(1,Iなど) / 《the O-》超人的なもの / 〈U〉《しばしばa ~》(攻撃・冗談・うそなどの)一発 / 《前に述べた可算名詞を受けて》『それ』 / 《修飾語を伴わないで》 / 《修飾語句を伴って》 / 《後》に「of+複数名詞・代名詞」を伴ってその名詞・代名詞の》『一つ』,一人 / 《後にanother, [the]otherと対照して》一つ,一方 / 《修飾語句を伴って》(特定の)『人』,者 / 《総称的に》『人』 / 私,自分
(また《文》upon)《位置・場所》…『の上に』,の上で,の上の / (また《文》upon)《運動・動作の方向・対象》…『に』[向かって] / 《話》…を身につけて / (また《文》upon)《近接して場所》…の近くに,…に面して,…の側に / 《特定の日時》…『に』 / 《状態》…『して』,…中で,…すると / (また《文》upon)…『について』,…に関して / 《目的》…『で』,…に / (また《文》upon)…に基づいて,…によって,…の支え(助け)で / 《所属を表して》(委員会・チームなどの)一員で / (また《文》upon)…を軸にして,…で / (また《文》upon)《前後に同じ名詞を並べて》…に加えて,…についで / 『上に』,『身につけて』 / (電気・水道・ガス・ラジオなどが)『ついて』,通じて / 行われて,続けて,従事して / 《時の副詞[句]を伴って》前方へ,ずっと
(液体・ガスなどの流れを調節する)『バルブ』,弁 / (血液の流れを調節する)弁,弁膜 / (管楽器の)バルブ / (2枚貝の)から,貝がら / 《英》真空管

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/13 19:10:23」(JST)

wiki en

[Wiki en表示]

Tilting disc inconel check valve

Check valve symbol on P&IDs. The arrow shows the flow direction.

A check valve, clack valve, non-return valve or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction.

Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid 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, or inexpensive. Check valves work 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.

An important concept in check valves is the cracking pressure which is the minimum upstream pressure at which the valve will operate. Typically the check valve is designed for and can therefore be specified for a specific cracking pressure.

Heart valves are essentially inlet and outlet check valves for the heart ventricles, since the ventricles act as pumps.

Technical terminology

Cracking pressure — the inlet pressure at which the first indication of flow occurs (steady stream of bubbles).

Reseal pressure — the pressure at which there is no indication of flow.

Back pressure — the differential pressure between the inlet and outlet pressures.

Types of check valves

A ball check valve in the open position to allow forward flow and closed position to block reverse flow

A ball check valve is a check valve in which the closing member, the movable part to block the flow, is a spherical ball. In some ball check valves, the ball is spring-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.

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 pumps, and refillable dispensing syringes. Although the balls are most often made of metal, they can be made of other materials, or in some specialized cases out of artificial ruby^{[citation needed]}. High pressure HPLC pumps and similar applications commonly use small inlet and outlet ball check valves with both balls and seats made of artificial ruby, for both hardness and chemical resistance^{[citation needed]}. 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 plastic body tightly-fitted inside a metal fitting which can withstand high pressure and which is screwed into the pump head.

There are similar check valves where the disc is not a ball, but some other shape, such as a poppet energized by a spring. Ball check valves should not be confused with ball valves, which is a different type of valve in which a ball acts as a controllable rotor to stop or direct flow.

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 positive pressure stops, the diaphragm automatically flexes back to its original closed position.^[1]

A swing check valve or tilting disc check valve is check valve in which the disc, the movable part to block the flow, swings on a hinge or trunnion, 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. The flapper valve in a flush-toilet mechanism 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 clapper valve, used in applications such firefighting 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 backwater valve (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.

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 any flow regardless of forward pressure.

A lift-check valve is a check valve in which the disc, sometimes called a lift, 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.

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 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. ^[2]

A duckbill valve 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.

A pneumatic non-return valve.

Multiple check valves can be connected in series. For example, a double check valve is often used as a backflow prevention device to keep potentially contaminated water from siphoning back into municipal water supply lines. There are also double ball check valves 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.

Applications

Pumps

The check valves on this steam locomotive are located under the small cover between the chimney and the main dome

Check valves are often used with some types of pumps. Piston-driven and diaphragm pumps such as metering pumps and pumps for chromatography 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 feed pumps or injectors which supply water to steam boilers are fitted with check valves to prevent back-flow.

Industrial processes

Check valves are used in many fluid systems such as those in chemical and power plants, and in many other industrial processes.

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.^[3] In aircraft and aerospace, check valves are used where high vibration, large temperature extremes and corrosive 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.^[4]^[5]

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 on both the fuel and oxidizer sources to ensure that the original gas cylinders remain pure and therefore nonflammable.

Domestic use

Some types of irrigation sprinklers and drip irrigation emitters have small check valves built into them to keep the lines from draining when the system is shut off.

Check valves used in domestic heating systems to prevent vertical convection, especially in combination with solar thermal installations, also are called gravity brake.

Rainwater harvesting systems that are plumbed into the main water supply of a utility provider may be required to have one or more check values fitted to prevent contamination of the primary supply by rainwater.

Hydraulic jacks use ball check valves to build pressure on the lifting side of the jack.

History

Frank P. Cotter 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 (U.S. patent #865,631).

Nikola Tesla invented a deceptively simple one-way valve for fluids in 1916, called a Tesla valve. It was patented in 1920 (U.S. patent 1,329,559).

Images

Hastelloy check valves
Stainless steel wafer check valve
Inconel check valve
Inside view of a tilting disc inconel check valve
Flanged nozzle inconel check valve or axial check valve
This Siamese clappered inlet allows one or two inputs into a deluge gun.
Inside hastelloy check valve, wafer configuration
Large carbon steel swing check valve
Disc for an alloy check valve also known as axial check valve
Wafer check valve

References

^ Wright, Stephen. "Norval valve performance". Northvale Korting. Retrieved 2009-05-19.
^ Fleming, Jennifer. "ValveMan Blog". ValveMan Brand VM6800 In-Line Check Valve- Product Overview. ValveMan LLC. Retrieved 1 August 2012.
^ http://www.valcor.com/nuclear-power/check-excess-flow-check-valves/
^ http://www.valcor.com/aircraft/aircraft-check-valves/
^ http://www.valcor.com/missiles-and-aerospace/aerospace-check-valves/

External links

Working Principle of Spring Check Valves
Check Valves Tutorial The operation, benefits, applications and selection of different designs, including lift, disc, swing and wafer check valves are explained in this tutorial
A picture of a microscopic checkvalve, a scaled down version of Tesla's original fluidic diode.
US Patent 1,329,559, Tesla's original fluidic diode (a test of a design showing very poor performance - n.b. the test protocol did not match the conditions described in the patent)
Check Valve Installation and Benefits

UpToDate Contents

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4. 経大動脈弁置換のためのイメージング imaging for transcatheter aortic valve replacement
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English Journal

Iatrogenic tracheal flap mimicking tracheal stenosis with resultant stridor.

Tan KL, Chong AW, Amin MA, Raman R.SourceDepartment of Otorhinolaryngology, Universiti Malaya Medical Centre, Kuala Lumpur, Malaysia.
The Journal of laryngology and otology.J Laryngol Otol.2012 May 14:1-5. [Epub ahead of print]
Objective:To illustrate a case of an iatrogenic mucosal tear in the trachea which caused a one-way valve effect, obstructing the airway and manifesting as post-extubation stridor.Case report:We report a case of iatrogenic tracheal mucosal tear secondary to violent movement during intubation. The pat
PMID 22578299

Migrating pseudomeningocele causing posterior fossa syndrome.

de Jong L, Engelborghs K, Vandevenne J, Weyns F.SourceDepartment of Neurosurgery, University Hospitals Leuven , Leuven , Belgium.
British journal of neurosurgery.Br J Neurosurg.2012 May 6. [Epub ahead of print]
We present two cases of spontaneous intracerebellar migration of a pseudomeningocele. This is a rarely reported complication of posterior fossa surgery with possible life threatening cerebellar mass effect. The probable mechanism is a slow but progressive cerebrospinal fluid (CSF) movement (one-way
PMID 22559723

Japanese Journal

空気肩関節造影検査後，棘窩切痕部ガングリオン内に空気が貯留した一例

村橋靖崇,廣瀬聰明,山下敏彦,岡村健司
肩関節 36(3), 1083-1085, 2012
… Because labral tears were confirmed arthroscopically in all patients on whom we performed arthroscopic decompression in our institution, we think that the one way valve mechanism causes ganglion cysts. … This case suggested that the detached labrum functioned as a check-valve from articular joint into the ganglion cyst. …
NAID 130002103518

ディフューザ型バルブレスマイクロポンプの解析的・実験的研究(流体工学,流体機械)

田中誠一,塚本寛,宮崎康次
日本機械学會論文集. B編 76(765), 839-844, 2010-05-25
… The pressure-loss in a nozzle is lower than that in a diffuser, therefore one-way flow is considered in the nozzle direction. …
NAID 110007619443