一个排气阀是一种装置，调节，指导或控制流量的流体 （ 气体 ， 液体 ， 流化床 固体或泥浆开幕）的，关闭或部分阻碍各个通道。 Valves are technically pipe fittings , but are usually discussed as a separate category.排气阀在技术上管 件 ，但通常是作为一个单独的讨论范畴。 In an open valve, fluid flows in a direction from higher pressure to lower pressure.在打开的排气阀，流体流动的方向，从更高的压力，降低压力。

      Valves are used in a variety of contexts, including industrial , military , commercial, residential, and transport .排气阀是用在各种情况下的，包括工业 ， 军事 ，商业，住宅和运输 。 The industries in which the majority of valves are used are oil and gas , power generation , mining , water reticulation , sewerage and chemical manufacturing . ^{[ citation needed ]}该行业 ，其中大部分用于排气阀是石油和天然气 ， 发电 ， 采矿 ， 水网 ， 污水处理及化学制品制造业 ^{。[ 来源请求 ]}

      In daily life, most noticeable are plumbing valves, such as taps for tap water .在日常生活中，最引人注目的是管道排气阀，这种水龙头的自来水 。 Other familiar examples include gas control valves on cookers, small valves fitted to washing machines and dishwashers , safety devices fitted to hot water systems , and valves in car engines.其他熟悉的例子包括对灶具燃气控制，小阀门安装在洗衣机和洗碗机 ，安全装置安装在热水系统 ，在汽车和发动机排气阀。 In nature, veins acting as valves are controlling the blood circulation ; heart valves control the flow of blood in the chambers of the heart and maintain the correct pumping action.在自然界中， 静脉作为排气阀控制血液循环 ， 心脏瓣膜控制血液的流量在心室的 ，保持正确的抽水行动。

        Like in case of human body, in industry too, the valves play a very vital role, be it transportation of drinking water, or control of ignition in a rocket engine.就像人体的情况下，行业也是这样，阀门起到非常重要的角色，无论是运输饮用水，或在火箭发动机点火控制。

      Valves may be operated manually, either by a handle , lever or pedal.阀门可手动操作，或者通过一个手柄 ， 手柄或踏板。 Valves may also be automatic, driven by changes in pressure , temperature , or flow.阀门也可能是自动的，在推动的变化由压力 ， 温度或流量。 These changes may act upon a diaphragm or a piston which in turn activates the valve, examples of this type of valve found commonly are safety valves fitted to hot water systems or boilers .这些变化可能采取行动的一个膜片或活塞这反过来又激活阀门，阀门这种类型的例子，发现常见的有安全阀门安装在系统或热水锅炉 。

More complex control systems using valves requiring automatic control based on an external input (ie, regulating flow through a pipe to a changing set point) require an actuator .更复杂的控制系统采用全自动控制阀，需要基于一个外部输入（即，调节管道流经一个不断变化的设定点）需要一个执行机构 。 An actuator will stroke the valve depending on its input and set-up, allowing the valve to be positioned accurately, and allowing control over a variety of requirements.行程执行器，阀门将其输入并根据设置，使阀门被精确定位，并允许在一个控制的各种要求。

排气阀