1. Basic definition
Parallel gate valve refers to a valve with sealing surfaces on both sides of the gate parallel to each other and perpendicular to the pipeline axis. It is opened and closed by the lifting and lowering movement of the gate. It is suitable for full-open or full-closed cutoff control and is not recommended for flow regulation. Its core design feature is the use of a parallel double gate structure, which is combined with a spring or a propping mechanism to enhance sealing.
2. Structural features
Sealing surface design
The sealing surface is a parallel plane, perpendicular to the center line of the pipeline, and the gate is fitted with the valve seat by spring preload or medium pressure.
Typical structures include:
Double gate with thrust wedge: suitable for low-pressure small and medium-caliber valves of DN50-DN400.
Spring preloaded double gate: The spring provides initial sealing force to reduce the risk of low-pressure leakage.
Full-bore design: The gate channel is consistent with the inner diameter of the pipeline to reduce fluid resistance.
Drive and transmission
Common drive methods include manual (handwheel), electric or pneumatic control, and some models use a structure with a mechanical propping device.
3. Working Principle
Sealing Mechanism
Low-pressure working condition: Spring preload or mechanical expansion mechanism pushes the double gate to fit the valve seat to form an initial seal.
High-pressure working condition: The medium pressure acts on the back of the gate, pushing it to further press the valve seat to form a self-enhanced seal.
Opening and closing characteristics
When the valve is closed, the gate completely covers the flow channel, and when it is opened, the gate moves to the top of the valve cavity to achieve full-bore flow.
4. Application scenarios
Applicable media
Water, sewage, particulate or viscous fluids (such as petroleum, chemical slurry).
Working conditions
Low-pressure system: Steam and oil pipelines with a nominal pressure of ≤1.0MPa.
Municipal and industrial: Medium-diameter pipelines (DN50-DN400) in urban water supply, sewage treatment plants, metallurgy and power industries.
