PURPOSE: To prevent liquid from leaking through nozzles in the condition that water spray is stopped, by a method wherein a nozzle of which the water- guiding pipe is inserted into the flowing-in hole of a flowing-in pipe and is fastened thereto, is screwed directing its head downward to a spray pipe, and the top end of an inlet for the nozzle is extended to the upper part of the inside of a spray pipe.

CONSTITUTION: The opening level of the top end of a pipe, which acts as an inlet for a nozzle 16, is positioned at the upper part of the inside of a spray pipe 8. In this way, the inside of the spray pipe 8 is filled with water supplied in the spray pipe 8, following which the water is supplied to the nozzles 16. Air in the spray pipe 8 is pushed-out to the inlets for the nozzles 16 by water pressure and is atomized from the nozzles 16 together with the water, and hence the air does not stay behind in the spray pipe 8. Thus the water pressure in the spray pipe is immediately lowered, water spray from the nozzles 16 is instantaneously stopped and water is prevented from leaking.