蝶式对夹止回阀的特点：1.蝶形止回阀的阀瓣呈圆盘状，在阀座通道的旋转轴上进行旋转运动。因为阀内的通道是流线型的，所以流压比蝴蝶式止回阀小，适合于低流速和流动不大变化的大口径的情况。蝴蝶式止动阀分为单瓣式、双瓣式和多半式三种。这三种形式主要根据阀门的口径来划分。目的是为了在媒体停止流动或逆流时减弱水力冲击。2.阀瓣围绕阀座内的销轴旋转的止回阀。碟式止回阀结构简单，只能安装在水平管道上，密封性较好。3.阀瓣沿着阀体中心线滑动的阀门。管道式止回阀是新出现的一种阀门，它的体积小，重量较轻，加工工艺性好，是止回阀发展方向之一。

The characteristics of butterfly check valve: 1. The valve disc of butterfly check valve is disc-shaped and rotates on the rotating axis of the valve seat channel. Because the channel inside the valve is streamlined, the flow pressure is lower than that of butterfly check valves, making it suitable for large-diameter situations with low flow rates and little change in flow. Butterfly stop valves are divided into three types: single disc, double disc, and half disc. These three forms are mainly divided according to the diameter of the valve. The purpose is to reduce hydraulic shock when the media stops flowing or flows backwards. 2. A check valve in which the valve disc rotates around the pin axis inside the valve seat. The disc check valve has a simple structure and can only be installed on horizontal pipelines, with good sealing performance. 3. A valve in which the valve disc slides along the centerline of the valve body. Pipeline check valve is a newly emerged type of valve, which has a small volume, light weight, and good processing technology, and is one of the development directions of check valves.

这种类型的阀门的作用是只允许介质向一个方向流动，而且阻止方向流动。通常这种阀门是自动工作的，在一个方向流动的流体压力作用下，阀瓣打开；流体反方向流动时，由流体压力和阀瓣的自重合阀瓣作用于阀座，从而切断流动。

The function of this type of valve is to only allow the medium to flow in one direction and prevent directional flow. Usually, this type of valve works automatically, and under the pressure of fluid flowing in one direction, the valve disc opens; When the fluid flows in the opposite direction, the pressure of the fluid and the self weight of the valve disc act on the valve seat, thereby cutting off the flow.

内螺纹止回阀,蝶式止回阀就属于这种类型的阀门，它包括旋启式止回阀和升降式止回阀。旋启式止回阀有一介铰链机构，还有一个像门一样的阀瓣自由地靠在倾斜的阀座表面上。为了确保阀瓣每次都能到达阀座面的合适位置，阀瓣设计在铰链机构，以便阀瓣具有足够有旋启空间，并使阀瓣真正的、与阀座接触。阀瓣可以全部用金属制成，也可以在金属上镶嵌皮革、橡胶、或者采用合成覆盖面，这取决于使用性能的要求。旋启式止回阀在完全打开的状况下压力几乎不受阻碍，因此通过阀门的压力降相对较小。升降式止回阀的阀瓣座落位于阀体上阀座密封面上。

Internal thread check valve and butterfly check valve belong to this type of valve, which includes swing check valve and lift check valve. The swing check valve has a hinge mechanism and a valve disc like a door that freely rests on the inclined valve seat surface. In order to ensure that the valve disc can reach the appropriate position on the valve seat surface every time, the valve disc is designed in a hinge mechanism so that the valve disc has sufficient swing space and truly contacts the valve seat. The valve disc can be made entirely of metal, or it can be embedded with leather, rubber, or a synthetic cover on top of the metal, depending on the performance requirements. When the swing check valve is fully open, the pressure is almost unobstructed, so the pressure drop through the valve is relatively small. The valve disc of the lift check valve is located on the sealing surface of the valve seat on the valve body.