To more uniformly disperse the liquid sprayed on a dampening roller by a nozzle by allowing an opening and closing means to communicate with the first end part of a chamber and allowing the nozzle to communicate with the second opposed end part of the chamber.

A first passage 26 communicates with a cavity 34 so that a plunger 30 permits the communication of the passage 26 with a second passage 38 at a second inside position and prevents the communication between the passages 26, 38 at a first outside position and the plunger 30 of a solenoid 28 controls the flow of the liquid passing through a nozzle assembly 16. The assembly 16 has a chamber 40 and the outer end part of the passage 38 communicates with the inner end part of the chamber 40 at the surface part of the block 22 forming the chamber 40. The assembly 16 has the nozzle 42 communicating with the outer end part of the chamber 40 allowing a liquid to flow through the chamber 40 and the nozzle 42 sprays the liquid on a dampening roller through an outside orifice 44. When the inner end part of the chamber 40 and the passage 38 become the same plane, the more uniform dispersion of the sprayed liquid is achieved and the optimum spray can be performed.