Arrangement for regulating the moistening solution mixture in a moistening solution preparation plant for an offset printing press

Claim 1

Arrangement for regulating the moistening solution mixture in a moistening solution preparation plant for use in an offset printing press comprising a tank having two separate spaces with one space containing a moistening solution mixture and the other space containing a moistening solution additive, a float switch positioned within the moistening solution mixture space, an injector above the moistening solution additive space, a suction pipe connected to the injector and extending downwardly into the space containing the moistening solution additive, a conduit system connected to said injector and suction pipe and including a line extending from said injector into said moistening solution mixture space, a flow detector in said conduit system and connected to said injector, a first solenoid valve connected to said flow detector, a second solenoid valve connected to said moistening solution mixture space, wherein the improvement comprises that a crystal sand filter and a circulating pump associated with said filter are located in said conduit system for filtering the moistening solution mixture from said moistening solution mixture space for feeding a portion of the filtered mixture to the printing press and for returning a portion into the moistening solution mixture space in said tank, a pH measuring electrode in said conduit system, a switch box, a first electrical line connecting said pH measuring electrode to said switch box, a second electrical line connecting said float switch to said switch box, a third electrical line connecting said first solenoid valve to said switch box, a fourth electrical line connecting said second solenoid valve to said switch box, said switch box including a line recorder, an acid content regulator a pH-meter and switches arranged to regulate the moistening solution mixture, said conduit system further comprising a first line connecting said mixture space to said filter through said pump, a feed line for flowing the moistening solution from said filter to the printing press, a first branch line connecting said feed line to said measuring electrode, a second branch line connecting said feed line to said mixture space, a second line connecting said measuring electrode to said mixture space, a return line for flowing the moistening solution from the printing press to said mixture space, a third line connecting a source of fresh water to said first and second solenoid valves, said solenoid valves being arranged so that one of said solenoid valves can be opened by said switch box by a signal from said measuring electrode while maintaining the other closed thereby selectively admitting the fresh water either directly into said mixture space or through said flow detector to said injector for withdrawing additive from said additive space through said suction pipe for mixture with the fresh water and flow into the mixture space, and said float switch arranged for operating at least one of said solenoid valves when the level in said mixture space drops below a selected level for adding make-up into said mixture space.