What type of hydrants have no main valve?

• A. Dry-barrel hydrants
• B. Wet-barrel hydrants
• C. Pumper hydrants
• D. Post hydrants

Answer: (B)

Hydrants are designed so that the presence or absence of a shutoff valve in the underground supply matters for freezing protection and how water reaches the hydrant. In a wet-barrel design, the hydrant is connected directly to a pressurized water main and the barrel remains filled with water at all times. Because the supply is already open to the hydrant, there isn’t a separate main valve located in the underground portion to control flow to the hydrant. That’s why this type is described as having no main valve.

In contrast, dry-barrel hydrants keep the main valve underground to protect it from freezing; the portion of the hydrant above ground can be dry when not in use, and water is admitted to the barrel only when the valve is opened. Pumper and post hydrants refer to other configurations and uses and aren’t defined by the absence of an underground main valve in the same way wet-barrel hydrants are.