Assuming that the channel diameter in a valve body is different (usually the diameter at the valve seat is smaller than that at the flange connection), it is called path shortening.

通径缩短能使零件尺度减小，开、闭所需力相应减小，一起可拓展零部件的运用规划。

Reducing the drift diameter can reduce the size of parts and the force required for opening and closing. Together, it can expand the application planning of parts.

通径缩短后。流体阻力丢掉增大。

After reducing the drift diameter. Fluid resistance increases.

在某些有些的某些工作条件下（如石油有些的输油管线），不允许选用通径缩短的阀门。这一方面是为了减小管线的阻力丢掉，另一方面是为了避免通径缩短后给机械清扫管线构成阻碍。

Under certain working conditions (such as oil pipelines), it is not allowed to select valves with shortened diameter. On the one hand, it is to reduce the resistance of the pipeline, on the other hand, it is to avoid the obstruction to the mechanical cleaning of the pipeline after the diameter is shortened.

闸 阀是作为截止介质运用，在全开时悉数流转直通，此时介质工作的压力丢掉更小。闸阀通常适用于不需要常常启闭，而且坚持闸板全开或全闭的工况。不适用于作为 调理或节约运用。关于高速活动的介质，闸板在有些翻开情况下可以致使闸门的振动，而振动又可以危害闸板和阀座的密封面，而节约会使闸板遭受介质的冲蚀。 从规划方法上，首要的区别是所选用的密封元件的方法。根据密封元件的方法，常常把闸阀分红几种不一样的类型，如：楔式闸阀、平行式闸阀、平行双闸板闸阀、楔 式双闸板闸等。更常用的方法是楔式闸阀和平行式闸阀。

The gate valve is used as the cut-off medium. When it is fully open, all flow through. At this time, the working pressure of the medium is the minimum. Gate valves are usually suitable for working conditions that do not need to be opened and closed frequently and insist on full opening or full closing of the gate. Not suitable for conditioning or economical use. With regard to the medium moving at high speed, the ram can cause the vibration of the gate in some cases, and the vibration can endanger the sealing surface of the ram and valve seat, and the RAM will be eroded by the medium. In terms of planning method, the primary difference is the method of sealing elements selected. According to the method of sealing elements, gate valves are often divided into several different types, such as wedge gate valve, parallel gate valve, parallel double gate valve, wedge double gate valve, etc. The most common methods are wedge gate valve and parallel gate valve.

这种类型的阀门的作用是只允许介质向一个方向活动，而且阻挠方向活动。通常这种阀门是自开工 作的，在一个方向活动的流体压力作用下，阀瓣翻开；流体反方向活动时，由流体压力和阀瓣的自重合阀瓣作用于阀座，然后堵截活动。其间止回阀就归于这种类型 的阀门，它包括旋启式止回阀和升降式止回阀。

The function of this type of valve is to allow the medium to move in only one direction and block the direction. Usually, the valve is self opening. Under the action of fluid pressure moving in one direction, the valve disc opens; When the fluid moves in the opposite direction, the fluid pressure and the self weight of the valve disc act on the valve seat, and then block the activity. Meanwhile, the check valve belongs to this type of valve, including swing check valve and lift check valve.

旋启式止回阀有一 介铰链安排，还有一个像门一样的阀瓣安闲地靠在倾斜的阀座表面上。为了确保阀瓣每次都能抵达阀座面的适合方位，阀规划在铰链安排，以便阀瓣具有满意有旋启 空间，并使阀瓣真实的、悉数的与阀座触摸。阀瓣可以悉数用金属制成，也可以在金属上镶嵌皮革、橡胶、或许选用构成覆盖面，这取决于运用功能的需要。旋启式 止回阀在彻底翻开的情况下，流体压力几乎不受阻挠，因此通过阀门的压力降相对较。

The swing check valve has a hinged arrangement and a valve disc like a door resting comfortably on the inclined seat surface. In order to ensure that the valve clack can reach the appropriate orientation of the valve seat surface every time, the valve is planned to be arranged on the hinge, so that the valve clack has a satisfactory swing space and makes the valve clack truly and fully touch the valve seat. The valve disc can be made of metal, or inlaid with leather and rubber on the metal, or selected to form the coverage, depending on the needs of the application function. When the swing check valve is completely opened, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively low.

升降式止回阀的阀瓣位于位于阀体上阀座密封面上。此阀门除了阀瓣可以安闲 地升降以外，其余有些如同截止阀一样，流体压力使阀瓣从阀座密封面上抬起，介质回流致使阀瓣回落到阀座上，并堵截活动。根据运用条件，阀瓣可以是全金属结 构，也可以是在阀瓣架上镶嵌橡胶垫或橡胶的方法。像截止阀一样，流体通过升降式止回阀的通道也是狭窄的，因此通过升降式止回阀的压力降比旋启式止回阀大 些，而且旋启式止回阀的流量遭到的束缚很少。

The disc of the lift check valve is located on the sealing surface of the valve seat on the valve body. Except that the valve disc can rise and fall freely, others are like stop valves. The fluid pressure lifts the valve disc from the sealing surface of the valve seat, and the medium backflow causes the valve disc to fall back to the valve seat and block the activity. According to the application conditions, the valve disc can be an all metal structure or a method of inlaying rubber pad or rubber on the valve disc frame. Like the stop valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow of the swing check valve is less constrained.