Which hydrant style always has water in it for immediate use by firefighters and is controlled by separate valves for each opening?

The wet barrel hydrant is designed to always maintain water within its structure, allowing for immediate accessibility in emergencies. This feature is especially vital in areas that do not experience freezing temperatures, as it ensures that firefighters can quickly access water without having to first activate any valves.

In a wet barrel hydrant, each outlet is equipped with its own valve. This allows firefighters to control the flow of water individually for each connection, making it possible to supply water to multiple hoses simultaneously. This design enhances the efficiency of firefighting operations, as it provides immediate and prioritized access to water based on the situation and needs of the firefighters on the scene.

The other hydrant styles have different functionalities. For instance, dry barrel hydrants are designed to prevent freezing by keeping the water supply below the frost line and rely on a main valve to open the water supply when it is needed. Post indicator valves and flow-through hydrants serve specific purposes related to system operation and configuration rather than providing immediate water availability in the way wet barrel hydrants do.