Valve Magazine - Summer 2008

main valve was connected by a long stem to a handle on top of the hydrant barrel that stood about two feet above the ground surface. Threads under the handle moved the stem and valve up or down when the handle was turned. A separate rod down the outside of the hydrant’s barrel and connected to the handle, also moved to control a small drain opening located below the frost line on the side of the barrel just above the main valve. It opened when the main valve was closed allowing water drainage to prevent freezing in winter. Hydrants of this type are called “dry barrel” because water is only in the upper part of the hydrant above the frost line during use (Figure 3).

One of the more challenging aspects of recording the history of fire hydrant design is the variety of designs that existed, especially from the middle of the 19th century. The variety stems in part from the great pride towns had in their water systems. Hydrants, perhaps the single most visible feature of a system, became objects of that pride and were cast with elaborate surface decorations. Like Philadelphia, almost every water system had its unique hydrant design custom made by a local foundry.

Figure 3—Historical records credit the Philadelphia Water System as the origin of the fire hydrant as we know it in the United States. This post-style hydrant, designed by Philadelphia’s water superintendent in 1803, used a conical main valve made of leather with a brass seat placed on top of the water main.

Americans Favor Philly Design At the time, both European-style “flush hydrants” and Philadelphia-style “post hydrants” were in use. It was also a time when several volunteer fire brigades might arrive at a fire at about the same time, vying for control of the available hydrants. It was pride, once again, that seemed to favor the post style winning out in America. According to an 1865 article, “In the hurly-burly of a fire-alarm...a fireman looks more picturesque seated on the hydrant which he has secured for his ‘machine,’ and can maintain his position better against the next com-ers, than over a flush case, without such salient points; besides this, it [the post-style hydrant]...certainly looks better in the engraving of his certificate or elaborate art adornments of his engine and fire house.” ¹It wasn’t just exterior decoration that set the early hydrants apart. Several ways were used to control water, including gate and compression main valves, and a “knuckle” arrangement (Figures 4 and 5). Most of today’s hydrants share the basic design concept of the 1803 Philadelphia design. The com-pression-style valve, now made of rubber, closes in the direction of water flow. Water pressure tends to force the valve into tighter contact with its seat, making it easier to achieve a reliable seal. Modern main valves are made to be removable through the top of the hydrant if repairs are needed. The stem terminates at the top of modern hydrants with an operating nut instead of a handle. The operating nut is usually in the shape of a penta-