Which type of hydrant is installed in areas where prolonged periods of subfreezing weather are common?

A dry barrel hydrant is designed specifically for use in areas where temperatures frequently fall below freezing. The key feature of a dry barrel hydrant is that it has a valve located below the frost line, which prevents water from remaining in the hydrant itself. When the hydrant is not in use, the valve closes, and any water in the hydrant drains out, preventing freezing and potential damage.

In contrast, wet barrel hydrants keep water in the barrel at all times, making them unsuitable for cold climates, as the water within them can freeze and damage the hydrant. Post indicator valves and standpipes are used for different purposes within fire protection systems, such as indicating the status of a valve or providing access to water from a building's plumbing system, but do not relate to the freezing issue in the same way. Thus, the dry barrel design is essential for maintaining functionality and safety in freezing conditions.