supply the handle has a cam that positively actuates a normally closed anti siphon valve so that water left in the wet pipe can fall under gravity to a collection chamber within the well casing beneath the piston lifting the handle again lowers the wet pipe and forces the water in the collection chamber back up the wet pipe at the same time the anti siphon valve will close and the wet pipe re opens the supply valve application_number US 84165504 A description referring now to the drawings wherein like reference characters represent corresponding elements throughout the several views the present invention will be described in the context of an exemplary yard hydrant 10 referring to fig1 the hydrant 10 generally includes a pipe assembly 12 a nozzle head 14 and a handle assembly 16 as shown in fig2 the pipe assembly 12 includes a well casing 18 a wet pipe 20 and a stand pipe 22 all being generally elongated cylinders concentric with axis 24 made of pvc or galvanized metal the well casing 18 has the largest diameter and is capped at both ends by end caps 26 and 28 lower end cap 26 fits over the bottom end of the well.