Why should a dry barrel hydrant be opened completely?

• A. The drain valve would be completely closed
• B. It would cause backflow
• C. It would cause air intake
• D. It would waste water

Answer: (A)

When a dry barrel hydrant is opened fully, the internal drain valve is driven to a closed position. That means water pressure from the supply can rise into the hydrant and out to the nozzle without it leaking away through the drain. Keeping the drain valve closed ensures you have maximum water supply available at the discharge and prevents unnecessary loss of water through the drain.

It wouldn’t cause backflow or air intake as a direct result of opening fully, and opening fully is not about wasting water; in fact, it prevents water from being wasted down the drain.