Swing check valves can be divided into the following main types according to the disc structure and sealing form, suitable for different working conditions:
1. Classification by the number of discs
Single disc swing type
Structure : A single disc-shaped disc is fixed to the valve body by a hinge.
Applicable scenarios : Medium-diameter pipelines (usually DN50-DN600), working conditions with stable fluid flow.
Limitations : A slow-closing device is required for large-diameter applications to reduce water hammer impact.
Dual disc swing type
Structure : Two symmetrical discs are used, which rotate synchronously through the central axis.
Advantages : Smaller flow resistance, dispersed closing impact force, suitable for large and medium-diameter pipelines (DN150-DN1200).
Typical applications : Large flow scenarios such as oil transportation and urban water supply mains.
Multi-disc swing type Structure : It is composed of multiple small-diameter discs in parallel, which are opened and closed independently.
Core value: significantly reduce the hydraulic impact when the super-large diameter (DN ≥ 600mm) valve is closed, and protect the sealing surface.
Application areas: large power station water supply system, chemical plant main process pipeline, etc.
2. Classification by sealing form Metal sealing type
Material: The valve disc and valve seat are made of metal hard seals such as stainless steel and alloy steel.
Features: high temperature resistance (up to 800℃), high pressure (PN250), suitable for steam, high temperature oil and other working conditions.
Soft sealing type
Material: The valve disc is inlaid with rubber or polytetrafluoroethylene (PTFE) sealing ring.
Advantages: good low temperature sealing, corrosion resistance, suitable for water and chemical media (such as acid and alkali).
Limitations: The working temperature is restricted by non-metallic materials (generally ≤200℃).
3. Special design types
Swing check valve with slow closing device:
The valve disc closing speed is delayed by hydraulic damping or heavy hammer mechanism, which effectively eliminates water hammer and is suitable for high impact risk scenarios such as pump outlet.
Wafer-type swing check valve:
Compact structure, light weight, directly clamped between pipe flanges, saving installation space (commonly used for DN15-DN600).
★Selection considerations Diameter matching:
DN≤600mm: single or double disc is preferred;
DN>600mm: multi-disc structure must be adopted.
Flow direction and installation:
When installed vertically, the medium needs to flow from bottom to top, and there is no direction restriction for horizontal pipes.
Sealing trade-offs:
Soft seals are selected for low-pressure conditions to ensure zero leakage; metal seals are selected for high temperature and high pressure to take into account durability.