止回阀按结构原理可分为以下几类，适用场景因介质特性、结构差异而不同。

　　Check valves can be divided into the following categories based on their structural principles, and their applicable scenarios vary depending on the characteristics of the medium and structural differences.

　　升降式止回阀升降式止回阀是通过阀座的上升和下降来实现止回功能，当流体流向反转时，阀座会被流体冲击使其关闭阀门，防止流体倒流。结构：沿阀体垂直中心线上下滑动，类似截止阀结构阀瓣，阀瓣沿轴向升降启闭，流道狭窄，阻力大，密封性能较好。适用场合：仅适用于清洁介质（如成品油、水、蒸汽）、小口径管道（DN≤200），且安装在水平管道。

　　Lift check valve Lift check valve achieves the check function through the rise and fall of the valve seat. When the fluid flow direction is reversed, the valve seat will be impacted by the fluid to close the valve, preventing fluid backflow. Structure: Sliding along the vertical center line of the valve body, similar to a globe valve structure valve disc, the valve disc rises and falls along the axial direction, with narrow flow channels, high resistance, and good sealing performance. Applicable occasions: Only suitable for cleaning media (such as finished oil, water, steam), small-diameter pipelines (DN ≤ 200), and installed in horizontal pipelines.

　　旋启式止回阀

　　Swing check valve

　　阀瓣为圆盘状，绕阀体内部的固定转轴做旋转启闭（类似门绕合页转动）。结构：阀瓣绕轴旋转启闭，流道宽敞，阻力小，单瓣/双瓣/多瓣设计适应不同口径。适用场合：适用于大口径管道（DN≥200）、介质含少量杂质的场景（如工业废水、冷却水系），可水平或垂直安装（流向向上）。

　　The valve disc is disc-shaped and rotates around a fixed axis inside the valve body to open and close (similar to a door rotating around a hinge). Structure: The valve disc rotates around the axis to open and close, with a spacious flow channel and low resistance. The single/double/multi disc design is suitable for different diameters. Applicable occasions: Suitable for large-diameter pipelines (DN ≥ 200) and media containing small amounts of impurities (such as industrial wastewater, cooling water systems), can be installed horizontally or vertically (with upward flow direction).

　　蝶式止回阀结构：阀瓣为圆盘状（类似蝶阀），绕阀体偏心轴旋转启闭；结构紧凑，体积小，重量轻，流道呈流线型；适合大口径低压管道。适用场合：适用于DN≥300的低压管道（如城市污水干管、污水处理厂总排管），可处理含悬浮物的污水，但需避免高黏度介质黏附阀瓣。

　　Butterfly check valve structure: The valve disc is disc-shaped (similar to a butterfly valve) and rotates around the eccentric axis of the valve body to open and close; Compact structure, small volume, light weight, streamlined flow channel; Suitable for large-diameter low-pressure pipelines. Applicable occasions: Suitable for low-pressure pipelines with DN ≥ 300 (such as urban sewage main pipes and sewage treatment plant main discharge pipes), which can treat sewage containing suspended solids, but high viscosity media should be avoided from adhering to valve discs.

　　球形止回阀结构：阀瓣为实心/空心球体，依靠介质压力推动球体沿流道滚动实现启闭；阀体内部有导向槽，限制球体仅沿轴向移动；阻力极小，抗堵塞能力强。适用场合：适用于含颗粒、纤维的介质（如污水提升泵出口、农业灌溉），低压大流量场景，不易被毛发、泥沙卡阻。

　　Spherical check valve structure: The valve disc is a solid/hollow sphere, which relies on the pressure of the medium to push the sphere to roll along the flow channel to achieve opening and closing; There is a guide groove inside the valve body, which restricts the ball from moving only along the axial direction; Extremely low resistance and strong anti blocking ability. Applicable occasions: Suitable for media containing particles and fibers (such as sewage lift pump outlet, agricultural irrigation), low-pressure and high flow scenarios, not easily blocked by hair and sediment.

　　活塞式止回阀

　　Piston check valve

　　结构：阀瓣为活塞状，沿阀体内部的精密导向孔做轴向滑动；通常内置弹簧（辅助关闭），部分无弹簧（依赖介质反向压力）。适用场合：仅用于清洁介质（如自来水、成品油等），严禁用于污水系统。

　　Structure: The valve disc is piston shaped and slides axially along the precision guide hole inside the valve body; Usually equipped with a built-in spring (to assist in closing), some without a spring (relying on the reverse pressure of the medium). Applicable occasions: Only used for cleaning media (such as tap water, refined oil, etc.), strictly prohibited for use in sewage systems.

　　轴流式止回阀轴流式止回阀，是通过流体压力差与弹簧力协同作用实现阀瓣的轴向启闭，正向流动时静压差推动阀瓣开启，反向流动或压力不足时弹簧力促使阀瓣快速关闭以防止逆流。结构：轴流式止回阀主要由阀体、阀座、阀瓣、弹簧、导向杆、导向套及导流罩等零部件组成，进口介质压力推动阀瓣开启，阀瓣进口侧表面为圆弧形；停泵后，进口压力逐渐降低，在弹簧作用下，阀瓣关闭，防止倒流；阀瓣关闭时平稳、减震、消声、减小水击。适用场合：压缩机出口、大功率泵出口（特别是高压水泵和油泵）、油气输送管道以及电站给水系统等。

　　Axial flow check valve is a type of valve that achieves axial opening and closing of the valve disc through the synergistic effect of fluid pressure difference and spring force. When flowing forward, the static pressure difference pushes the valve disc to open, and when flowing backward or under pressure, the spring force quickly closes the valve disc to prevent backflow. Structure: Axial flow check valve is mainly composed of valve body, valve seat, valve disc, spring, guide rod, guide sleeve, and guide cover. The inlet medium pressure pushes the valve disc to open, and the inlet surface of the valve disc is arc-shaped; After stopping the pump, the inlet pressure gradually decreases, and under the action of the spring, the valve disc closes to prevent backflow; When the valve disc is closed, it is smooth, shock-absorbing, soundproof, and reduces water hammer. Applicable occasions: compressor outlet, high-power pump outlet (especially high-pressure water pump and oil pump), oil and gas transmission pipeline, and power plant water supply system, etc.

　　橡胶瓣止回阀

　　Rubber flap check valve

　　结构：阀瓣为橡胶材质，弹性好，密封面不易磨损，流道通畅。适用场合：适用于污水、雨水等含杂质介质，中小口径管道（DN50~DN300），抗堵塞和耐腐蚀性能优于金属瓣。

　　Structure: The valve disc is made of rubber material, with good elasticity, the sealing surface is not easily worn, and the flow channel is smooth. Applicable occasions: Suitable for media containing impurities such as sewage and rainwater, small and medium-sized pipelines (DN50~DN300), with better resistance to blockage and corrosion than metal plates.

　　梭式止回阀（轴流式）梭式止回阀（又称“滑块式止回阀”“梭阀”）属于升降式止回阀的特殊衍生类型，其核心设计是将传统“圆盘/圆柱阀瓣”替换为“梭形滑块”，结构与性能具有显著特殊性。结构：阀瓣为梭形（两端尖、中间粗）滑块；阀体内部有对称的流线型导向腔，滑块仅能沿轴向做往复滑动（类似“梭子在织布机中移动”）；部分型号内置轻量化弹簧（辅助滑块复位，减少关闭滞后），流道全程无死角、无突出部件。性能特点：①压力损失极小：梭形滑块与流线型流道匹配，介质流动阻力远低于旋启式、蝶式。关闭速度快：②滑块滑动阻力小，且对称结构受力均匀，反向介质压力可瞬间推动滑块密封，水锤风险低。③抗杂质能力强：流道无转轴、凹槽等易卡堵结构，少量杂质可随介质排出，不易卡住滑块。④安装灵活：可水平或垂直安装（滑块重力影响小），适用角度范围广。

　　Shuttle type check valve (axial flow type) Shuttle type check valve (also known as "slide type check valve" or "shuttle valve") belongs to a special derivative type of lift type check valve. Its core design is to replace the traditional "disc/cylindrical valve disc" with a "shuttle shaped slide block", and its structure and performance have significant characteristics. Structure: The valve disc is a shuttle shaped (pointed at both ends, thick in the middle) slider; There is a symmetrical streamlined guide cavity inside the valve body, and the slider can only slide back and forth along the axial direction (similar to "shuttle moving in a loom"); Some models are equipped with lightweight springs (to assist in resetting the slider and reduce closing hysteresis), and the entire flow path has no dead corners or protruding parts. Performance characteristics: ① Minimal pressure loss: The shuttle shaped slider matches the streamlined flow channel, and the medium flow resistance is much lower than that of the rotary and butterfly types. Fast closing speed: ② The sliding resistance of the slider is small, and the symmetrical structure is uniformly stressed. The reverse medium pressure can instantly push the slider seal, and the risk of water hammer is low. ③ Strong anti impurity ability: The flow channel has no shaft, groove or other easily clogged structures, and a small amount of impurities can be discharged with the medium, making it less likely to get stuck in the slider. ④ Flexible installation: can be installed horizontally or vertically (with minimal influence of slider gravity), suitable for a wide range of angles.