Control apparatus for silver halide emulsion making

Claim 1

Apparatus for controlling the flow rate of a salt solution into a precipitation vessel of the type used in the preparation of a silver halide emulsion, said apparatus comprising: (a) means for containing a quantity of salt solution and having an outlet and return inlet; (b) first conduit means, connecting said outlet to said return inlet, for providing a closed path outside of said containing means for the salt solution; (c) second conduit means for directing salt solution into a precipitation vessel; (d) valve means, located in the closed path and movable between a first position and a second position, for selectively directing the salt solution from the container outlet to said return inlet or into said second conduit means; (e) means for moving solution from said container through said first conduit means at a predetermined rate; (f) means for sensing the flow rate of said solution through said first conduit means whereby establishment of an equilibrium flow rate can be determined prior to directing said salt solution into the vessel; (g) means for sensing the pAg of the solution within such a precipitation vessel after initial introduction of said salt solution and for producing a signal representative thereof; (h) means for generating a reference signal in accordance with a desired pAg profile; and (i) means for comparing the signal from said sensing means with said reference signal for controlling the flow rate of the salt solution into said vessel subsequent to the initial introduction of said salt solution.