How can the vertical fire hydrant be properly closed?
Most vertical fire hydrants sold today are closed inside, and the cone closes from the bottom to the top. During the closing process, the cone is pulled from below into a cylindrical seal region to close the hydrant by initial radial compression. If the upper drain valve is accidentally closed before the fire hydrant is closed, the top of the hydrant will be filled with water. If the cone is pushed to the seal area when closed, the water at the upper part of the hydrant will not be removed until the hydrant is closed. When the closed cone moves up and closes the hydrant, it will squeeze the existing water.
When the vertical fire hydrant is closed, unless the at least one discharge valve is slightly opened, the executing parts are damaged, and the shutoff valve of the vertical fire hydrant is completely damaged.
When water can no longer be squeezed, it produces a sharp surge of pressure. In this case, assuming that more than 50bar, the upper part of the hydrant continues to exhibit allowable operating pressure. As a result, the operation pressure is increased when the hydrant is operated. If the operator closes the fire hydrant with excessive force, the nut of the drive rod will be damaged, resulting in deformation or even damage to the taper fastener of the valve body. Normally, the damage of fire hydrants will not be noticed at first, but such damage will affect the use of the whole hydrant when the fire hydrant is used again.
