In what type of fire hydrant design is the main valve located below ground level?

In the context of fire hydrants, the design where the main valve is located below ground level is referred to as the dry-barrel hydrant. This design is particularly advantageous in colder climates, as it prevents water from remaining in the hydrant's barrel when it is not in use, thereby reducing the risk of freezing. When the hydrant is not activated, the main valve is closed, and water is contained below the frost line, which helps maintain the functionality and safety of the hydrant in freezing temperatures.

Additionally, the dry-barrel hydrant typically features a simple mechanism that allows for easy operation. When the hydrant is opened, the water flows from the underground supply line, through the main valve, and up through the barrel for firefighting purposes. This design effectively combines safety and efficiency, making it a common choice for many municipalities.

In contrast, the wet-barrel hydrant design has the valve situated above ground and is filled with water at all times. A flush hydrant is designed to be flush with the ground to reduce tripping hazards and is often used in locations like parking lots. A submersible hydrant generally refers to designs specifically made for use in areas that may be submerged under water, which is a distinct concept