A gate valve controls fluid flow by inserting a rectangular gate or wedge into the path of the fluid.
Understanding Gate Valve Operation
Gate valves are primarily designed for on/off service rather than flow regulation. Here's a more detailed look:
- Mechanism: The valve operates using a threaded stem. This stem connects the actuator (like a hand wheel or motor) to the valve's gate. When the actuator is turned, the stem moves the gate up or down.
- Positioning: The rectangular gate moves perpendicularly to the fluid's flow direction.
- Open Position: When the gate is fully withdrawn from the flow path, the valve allows unrestricted fluid flow.
- Closed Position: When the gate is fully inserted into the flow path, it blocks the fluid flow entirely.
- Stem Type: A rising stem valve allows users to visually check the valve's position. This is because the stem's position will change as the valve opens or closes.
Key Features and Practical Insights:
- Full Flow: When fully open, a gate valve provides minimal flow restriction, making it suitable for applications where unrestricted flow is needed.
- Tight Shut-off: When closed, the gate creates a tight seal to prevent leaks.
- Not for Throttling: Gate valves aren't designed for throttling (partially opening to regulate flow rate). Doing so can damage the valve.
Examples:
- Water Mains: Gate valves are commonly used in water mains to isolate sections for maintenance.
- Oil & Gas Pipelines: They're used to control the flow of fluids through long pipelines.
- Industrial Processes: Gate valves are used in various industrial processes to stop or start fluid flow.
Table: Gate Valve Operation Summary
| Feature | Description |
|---|---|
| Control | Rectangular gate/wedge inserted into the flow path. |
| Operation | Threaded stem moved by actuator (hand wheel, motor). |
| Flow Control | Primarily on/off service. Not suitable for throttling. |
| Stem Type | Rising stem indicates position visually. |
