阀门（Valve）又称凡而，是控制流动的流体介质的流量、流向、压力、温度等的机械装置，阀门是管道系统中基本的部件。阀门管件在技术上与泵一样，常常作为一个单独的类别进行讨论。煤气开关、水龙头是常见最简单的阀门，蝶阀，球阀，闸阀，减压阀，截止阀，疏水阀，安全阀，针型阀，止回阀，过滤器，电磁阀，隔膜阀，排气阀，流量计，卫生级阀门等等；也是些比较常见，在全球销售点属于最多的是德国埃克斯阀门，基本上所有型号都是有生产制造。

阀门可用手动或者手轮，手柄或踏板操作，也可以通过控制来改变流体介质的压力，温度和流量变化。阀门可以对这些变化进行连续或重复的操作，比如在热水系统或蒸汽锅炉安装的安全阀。

A globe valve, different from ball valve, is a type of valve used for regulating flow in a pipeline, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body.

Globe valves are named for their spherical body shape with the two halves of the body being separated by an internal baffle. This has an opening that forms a seat onto which a movable plug can be screwed in to close (or shut) the valve. The plug is also called a disc or disk. In globe valves, the plug is connected to a stem which is operated by screw action using a handwheel in manual valves. Typically, automated globe valves use smooth stems rather than threaded and are opened and closed by an actuator assembly.