If a nozzle is quickly shut down, where does the water hammer go?

When a nozzle is quickly shut down, a phenomenon called water hammer occurs, which is a shock wave resulting from the abrupt stopping of water flow. This sudden change in pressure travels back through the piping system.

The correct choice indicates that the water hammer travels to the hydrant and water main. In this scenario, when the flow is suddenly stopped, the kinetic energy of the moving water generates a pressure wave that propagates upstream toward the source of the water, which includes the hydrant and the main supply lines. The existing pressure in these systems helps absorb some of the shock, but significant forces can still be transmitted through the pipes, potentially leading to stress and failure if not properly managed.

Other options imply that the water hammer's impact is limited to the tank, pump, or atmosphere, which doesn't accurately represent how the pressure wave behaves within a closed hydraulic system. The water hammer effect predominantly affects the joints and connections of the system leading back to the water source, including the hydrant and water main, making that choice the most accurate reflection of the phenomenon.