SINKING HYDRANT

摘要

A riser tube rigid with a piston head is vertically reciprocable in a cylindrical housing to which water under pressure may be admitted from the bottom to raise the tube into an elevated position, in which its tip extends above the ground, or through a lateral port near the top of the housing to lower the tube into a retracted position below ground. The piston head has a peripheral groove which communicates with the bore of the tube and, in the extended position, registers with an upper set of holes in the housing wall which are connected through a stationary external sleeve with a lower set of holes, lying then beneath the piston head, whereby water from a distributing pipe of an irrigation system can enter the riser tube after having elevated same into that position.