Fire Hydrant Hydrants Early methods of obtaining water for firefighting purposes were crude. Water systems used hollowed-out logs for water mains. Pits were dug at specified intervals to expose the mains. A hole was made in the main and a wooden plug was inserted. These plugs were known as "fire plugs, " and this term is still sometimes used to identify hydrants. When a fire occurred, the wooden plug was removed from the main, water filled the pit, and fire apparatus drafted from the pit. However, the flow of water was so meager that the system was seldom effective. Cast iron pipe permitted the system pressure to be increased, and this led to the development of the post-type fire hydrant. An opening at the upper end of the standpipe provided a place for the fire pumpers to receive their supply. Two basic types of fire hydrants used today are dry barrel and wet barrel. FIRE PROTECTION SYSTEMS Hydrant Installations For hydrants to be immediately useful, they must be kept clear of obstructions such as fences, walls, landscaping, and snow. The center of the large opening should be a minimum of 18 inches above grade. The hydrant must be far enough from any adjacent object to allow the hydrant wrench to turn in a continuous movement and to allow for hose connection. The caps on the openings and the threads need to be inspected on a periodic basis to assure that they operate freely and that the hose couplings can be connected. Any hydrants found to be nonfunctional should be reported to the utility authority and a followup inspection made to be sure the hydrant was repaired and placed in service. One of the most common problems with out-of-service hydrants is that someone failed to turn on the control valve for the hydrant after installation or maintenance. Usually each hydrant on a system will have its dedicated valve so that only one hydrant will have to be out of service for repair or replacement. Hydrants come in many styles. Utility companies usually will have one type of hydrant on their system; however, some communities may have more than one design of hydrant on the system. Some large developments have hydrants designed to add to the aesthetics of the development.