良工阀门：截止阀为什么要“低进高出”？

　　Lianggong Valve: Why do globe valves have "low inlet and high outlet"?

　　在管道安装中，截止阀是常用的阀门之一。但很多人在安装时都会疑惑：为什么阀体上的箭头指向“低进高出”？

　　In pipeline installation, globe valve is one of the commonly used valves. But many people may wonder during installation: why does the arrow on the valve body point to "low in, high out"?

　　截止阀的工作原理截止阀通过阀杆驱动阀瓣垂直升降实现启闭。阀瓣落下压紧阀座时切断管路，阀瓣抬起脱离阀座时管路连通。

　　The working principle of a globe valve is that it opens and closes by driving the valve disc vertically up and down through the valve stem. When the valve disc falls and presses the valve seat tightly, the pipeline is cut off. When the valve disc lifts and separates from the valve seat, the pipeline is connected.

　　为什么要“低进高出”开启省力，密封性强：阀门开启时，介质从下方进入，压力向上顶起阀瓣，起到助开作用，操作更省力；关闭时，阀瓣顺着流向压向阀座，即使是人力也能实现严密密封。

　　Why do we need "low in, high out" to open with ease and strong sealing: When the valve is opened, the medium enters from below, and the pressure pushes up the valve disc, which helps to open and makes the operation more effortless; When closed, the valve disc is pressed towards the valve seat along the flow direction, and even manual labor can achieve a tight seal.

　　延长使用寿命：阀门关闭状态下，介质压力被阀瓣隔绝在下方，阀盖密封垫和阀杆填料不承压、不受介质冲刷，填料寿命大幅延长，泄漏概率也明显降低。

　　Extended service life: When the valve is closed, the medium pressure is isolated below by the valve disc, and the valve cover gasket and valve stem packing are not under pressure or subject to medium erosion. The packing life is significantly extended, and the probability of leakage is also significantly reduced.

　　维修方便：阀门全关且管道有旁路时，可以直接排空出口端，更换阀杆填料，无需拆卸整台阀门。

　　Easy maintenance: When the valve is fully closed and there is a bypass in the pipeline, the outlet end can be directly emptied and the valve stem packing can be replaced without disassembling the entire valve.

　　适用场景：绝大多数常规工况，尤其是小口径、中低压的蒸汽、水、油管路。装反了会怎样？关阀困难：关阀时介质从阀瓣上方压下来，操作扭矩大大增加。如果强行启闭，很容易造成阀杆弯曲。

　　Applicable scenarios: The vast majority of conventional operating conditions, especially for small-diameter, medium low pressure steam, water, and oil pipelines. What would happen if I installed it backwards? Difficulty in closing the valve: When closing the valve, the medium is pressed down from above the valve disc, greatly increasing the operating torque. If forcibly opened or closed, it is easy to cause the valve stem to bend.

　　密封失效：介质压力会持续顶着阀瓣，无法形成自密封，即使用力关闭阀门，阀瓣阀座也很难贴合，容易出现介质泄漏问题。阀门老化加速：阀门关闭状态下介质压力直接作用在阀杆填料上，长期冲刷会加速填料的变形和碎裂，显著缩短阀门的使用寿命。

　　Sealing failure: The medium pressure will continue to press against the valve disc, making it impossible to form a self seal. Even if the valve is forcefully closed, the valve disc and seat are difficult to fit, which can easily lead to medium leakage problems. Accelerated valve aging: When the valve is closed, the medium pressure directly acts on the valve stem packing, and long-term flushing will accelerate the deformation and fragmentation of the packing, significantly shortening the service life of the valve.

　　“高进低出”并非完全不能用，在大口径（DN200以上）或高压差工况下，如果还是低进高出，巨大的介质压力会死死顶住阀瓣，人力根本关不动，这时更适合采用“高进低出”。

　　High in and low out "is not completely unusable. In large-diameter (DN200 or above) or high-pressure differential conditions, if low in and high out are still used, the huge medium pressure will firmly press against the valve disc, making it impossible to close manually. In this case," high in and low out "is more suitable.

　　截止阀的“低进高出”适配绝大多数工况，“高进低出”是特殊场景的补充，安装时务必参照阀体上的箭头标识，避免装错流向引发安全事故。

　　The "low inlet and high outlet" of the globe valve is suitable for most working conditions. "High inlet and low outlet" is a supplement to special scenarios. When installing, it is necessary to refer to the arrow markings on the valve body to avoid installing in the wrong direction and causing safety accidents.

　　本文由 良工阀门 友情奉献.更多有关的知识请点击 http://www.jnlgvf.com/ 真诚的态度.为您提供为全面的服务.更多有关的知识我们将会陆续向大家奉献.敬请期待.

　　This article is a friendly contribution from Lianggong Valve For more related knowledge, please click http://www.jnlgvf.com/ Sincere attitude To provide you with comprehensive services We will gradually contribute more relevant knowledge to everyone Coming soon.