If a gate valve has a flow arrow indicated on it, it is because the gate valve has a -------.

A gate valve typically features a flow arrow to indicate the correct flow direction for optimal operation, and this aspect is particularly relevant when a double gate design is in use. In a double gate valve, there are two gates that can independently seal against the flow, allowing for better throttling and sealing capabilities compared to a single gate valve. The flow arrow helps ensure that the flow direction aligns with the design and functionality of the valve, promoting efficient operation and preventing potential issues such as backflow or improper sealing.

While single gate, revolving gate, and quick opening designs serve different purposes, they typically do not require the same level of attention to flow direction as found in a double gate configuration. The inclusion of a flow arrow signifies the necessity to follow the specified orientation for correct performance, underscoring the unique characteristics of the double gate valve and its operational advantages.