The core difference between piston check valve (i.e. lifting check valve) and swing check valve is reflected in the working principle, structural design and application scenarios. The specific differences are as follows:
1. Working principle and structural difference
Piston check valve
Movement mode: The valve disc slides up and down along the vertical center line of the valve body, similar to the piston movement (so it is also called lifting type).
Closing mechanism: The valve disc is sealed by the weight of the valve disc + the backflow pressure of the medium. When closed, the valve disc sits vertically.
Structural features: The valve body structure is similar to the stop valve, the flow channel is "L" or "Z" shaped, and the fluid resistance is large.
Swing check valve
Movement mode: The valve disc (disc-shaped) rotates and swings around the hinge axis, similar to the opening and closing of the door leaf.
Closing mechanism: It is closed by rotating through the rocker lever mechanism, and the closing angle is limited by the rotating shaft.
Structural features: The flow channel is streamlined, with less resistance, and the valve disc hardly blocks the flow channel after opening.
2. Installation and applicable working conditions Installation restrictions
Piston type: Only horizontal pipeline installation is allowed, and the valve disc cannot be self-repositioned when installed vertically.
Swing type: Can be installed in horizontal, vertical or inclined pipelines (the medium needs to flow from bottom to top when installed vertically)
Performance Comparison
| Features | Piston Check Valve | Swing Check Valve |
|---|---|---|
| Sealing | Better (valve disc vertically presses the cover tightly) | Weak (rotational closing is susceptible to inertia) |
| Fluid resistance | Large resistance (many flow channel turns) | Low resistance (streamlined channel) |
| Water hammer resistance | Poor (large closing shock) | Can be optimized through multi-petal/damping design |
| Large-caliber applicability | Only for small diameter (DN≤50) | Supports extra large diameter (DN＞2000) |
3. Typical application scenarios
Application scenarios of piston check valves
High-pressure small-diameter pipelines (such as boiler water supply systems, DN≤50 high-pressure pipelines);
Occasions requiring strict sealing (such as steam systems).
Application scenarios of swing check valves
Large-flow, low-velocity pipelines (such as municipal water supply and drainage, crude oil pipelines);
Particle-containing media (choose carbide seals);
Vertical/inclined installation requirements (such as pump room risers).
4. Maintenance and selection recommendations
Maintenance difficulty:
The piston type has a simple structure, but the valve disc guide sleeve is easy to get stuck and needs to be lubricated regularly;
The swing type hinge pin is easy to wear, and the large-diameter multi-disc valve is complicated to maintain.
Selection priority direction:
Sealing priority/small-diameter high pressure → piston type;
Low resistance/large diameter/flexible installation → swing type.
