In Australian commercial construction projects, a gate valve is a type of valve used to control the flow of liquids through a pipeline. It operates by lifting a gate or wedge out of the path of the fluid. Gate valves are typically used when a straight-line flow of fluid and minimum restriction is desired. They are not suitable for throttling purposes, as they are designed to be fully open or fully closed.

Key characteristics of gate valves in this context include:

1. Design: Gate valves have a simple design with a flat or wedge-shaped gate that slides up and down to open or close the valve. This design allows for a tight seal when the valve is closed.

2. Operation: They are operated by a handwheel, electric motor, or actuator, which moves the gate up and down. The operation is generally slower compared to other types of valves, like ball valves.

3. Applications: In commercial construction, gate valves are commonly used in water supply systems, wastewater treatment plants, and other applications where a full flow or shut-off is required.

4. Materials: They are typically made from materials such as cast iron, stainless steel, or brass, depending on the specific requirements of the project, including pressure, temperature, and the type of fluid being controlled.

5. Advantages: Gate valves provide a good seal and are cost-effective for applications where the valve is not frequently opened and closed. They also have a low pressure drop when fully open.

6. Limitations: They are not suitable for throttling or regulating flow, as partially open gate valves can cause vibration and damage to the gate and seat. Additionally, they require more space for installation compared to some other valve types.