Net weight dispensing system and method
AssigneeThe Dow Chemical Company
InventorsQ. Gordon von Nehring, John O. Beyer
Life of this patent
Estimating the term…
Abstract
A method and system for dispensing a fluid to provide a predetermined weight percent concentration of a sample material to the fluid. An estimated density value for the fluid is used to determine the volume of fluid to dispense in an initial injection of fluid which is less than the total volume of fluid required to achieve the predetermined weight percent concentration. A working fluid density is then determined from the volume of fluid dispensed and a measurement of the weight of the fluid dispensed. The working density is then used to determine the volume of fluid to dispense in a subsequent injection. Preferably, at least three fluid injections are performed, and the working density is determined after each fluid injection.
Claims30
A method of dispensing a fluid to provide a predetermined weight percent concentration of said fluid relative to a sample material, comprising the steps of:
- weighing a vessel;
- introducing a quantity of said sample material into said vessel and reweighing said vessel with said sample material contained therein;
- determining a target weight of said fluid in response to the weight of said sample material, and determining a target volume of said fluid to add to said vessel from the combination of said target weight and an initial density value of said fluid;
- dispensing a predetermined portion of said target volume of said fluid to said vessel which is less than said target volume, and reweighing said vessel with said sample material and fluid contained therein;
- determining a working density of said fluid in response to said second reweighing step, and determining a volume of fluid to be added to said vessel from said working density in order to substantially achieve said target weight of said fluid;
- and
- dispensing at least one additional volume of said fluid to said vessel to substantially achieve said target weight of said fluid.
A system for dispensing a fluid to provide a predetermined weight percent concentration of a sample material said fluid, comprising
- balance means for measuring the weight of a quantity of said sample material introduced into a vessel and the weight of selected fluid volumes subsequently added to said vessel, and for producing a signal indicative of the weight being measured;
- dispensing means for delivering selected volumes of said fluid to said vessel;
- input means for identifying a density characteristic of said fluid, and for identifying said predetermined weight percent concentration of said sample material in said fluid;
- controller means, operatively connected to said balance means, said input means and said dispensing means, for causing said dispensing means to add selected volumes of said fluid to said container to substantially achieve said predetermined weight percent concentration in a programmed sequence of fluid injections of variable volume in which the density of said fluid is determined after at least one of said fluid injections.
A method of dispensing a fluid to provide a predetermined weight percent concentration of said fluid relative to a sample material, comprising the steps of:
- weighing a vessel;
- introducing a quantity of said sample material into said vessel and reweighing said vessel with said sample material contained therein;
- determining a target weight of said fluid in response t the weight of said sample material, and determining na initial volume of said fluid to add to said vessel from a predetermined portion of said target weight of said fluid and an initial density value of said fluid, said predetermined portion of said target weight of said fluid being less than said target weight;
- dispensing said initial volume of said fluid to said vessel, and reweighing said vessel with said sample material and fluid contained therein;
- determining a working density of said fluid in response to said second reweighing step, and determining at least one additional volume of fluid to add to said vessel from said working density in order to substantially achieve said target weight of said fluid;
- and
- dispensing said additional volume of said fluid to said vessel.
A method of preparing an admixture of materials of predetermined concentration;
- the method comprising:
- (a) weighing a first material of the admixture;
- (b) calculating the target weight of a second material of the admixture which when admixed with the first material would achieve the desired predetermined concentration;
- (c) converting a portion of the calculated target weight to a corresponding volume based on an initial density of the second material, and dispensing the corresponding volume of the second material;
- (d) determining the weight of the dispensed second material;
- (e) calculating the density of the second material based on the volume of the second material determined in step (c) and the weight of the second material determined in step (d);
- (f) calculating the residual weight of the second material necessary to reach the target weight;
- (g) converting at least a portion or all of the residual weight to a corresponding residual volume using the calculated density of step (d) and dispensing the residual volume of the second material;
- (h) admixing the materials to prepare said admixture of materials of predetermined concentrations.
Dependencies are inferred from the claim text.