Fire Hydrants & ValvesType of fire hydrant used in locations that freeze. The main valve is located below ground and a drain valve allows water to drain from barrel when the main valve is closed. By jay@americanwatercollege.org | January 19, 2017 | Certification Exams . Distribution . Water Treatment | Tags: Certification Exam Prep, Distribution System, Dry-Barrel Hydrant, Fire Hydrants & Valves, Water Treatment