Proportioner

A proportioning system for creating admixture from diluent and concentrate comprises accumulators which are alternatively repetitively recharged so that one is always on-line. Recharging is controlled by a fluid system including a piston assembly for injecting a measured charge of concentrate into an accumulator being recharged. Diluent is introduced by opening and closing a valve from the diluent supply with the recharging being activated and terminated by level sensing switches associated with the accumulators. Electrical control circuitry and a stroke adjustment mechanism for the piston assembly are also disclosed.

What is claimed is:

1. Apparatus for mixing two liquids, normally a concentrate and a diluent, to form an admixture of desired concentration and for delivering admixture to work stations, said apparatus comprising a plurality of accumulators for accumulating admixture upstream of the work stations, a reservoir for containing one of said liquids, a supply of the other of said liquids, a delivery line for delivering admixture to the work stations, means for selectively connecting said accumulators on and and off said delivery line, means for recharging an off-line accumulator while another of said accumulators is on-line, said recharging means comprising a piston assembly which is operable to draw a measured charge of said one liquid from said reservoir and to inject the measured charge into a particular off-line accumulator which is being recharged, a valve for controlling the introduction of said other liquid into the particular accumulator being recharged, sensing means for sensing different levels of admixture in said accumulators, and control means for opening said valve to cause said other liquid to flow into the particular accumulator being recharged in response to said sensing means sensing a given low level of admixture in the particular accumulator being recharged, and for closing said valve in response to said sensing means sensing a given high level of admixture in the particular accumulator being recharged, said sensing means defining a known volume in each accumulator between the given high and low levels thereof thereby to attain the desired admixture concentration in a fully recharged accumulator per measured charge of said one liquid injected into the accumulator during recharging.

2. Apparatus as set forth in claim 1 in which there are two accumulators which are repetetively alternatively operated to on-line and off-line connection with the delivery line to the work stations.

3. Apparatus as set forth in claim 2 in which said one liquid is concentrate and said other liquid is diluent.

4. Apparatus as set forth in claim 2 in which said sensing means comprises a pair of level switches for each accumulator.

5. Apparatus as set forth in claim 2 in which said two liquids have a path of confluence to the particular accumulator being recharged.

6. Apparatus as set forth in claim 5 including a further valve in said path of confluence which is selectively operated by said control means to repetitively alternately conduct the confluent flow of the two liquids to the accumulators.

7. Apparatus as set forth in claim 6 including venting and pressurizing means associated with said accumulators and operated by said control means for alternately repetitively pressurizing and venting said accumulators such that the headspace of the accumulator which is online is pressurized and that of the accumulator which is off-line is vented.

8. Apparatus as set forth in claim 2 in which said piston assembly comprises a variable displacement volume chamber into which said one liquid is drawn from said reservoir on a return stroke of the piston and which is effective on the advance stroke of the piston to inject said one liquid into the particular accumulator being recharged, and a stroke adjustment mechanism associated with said piston assembly for adjusting the volume displacement of said chamber to a desired measure for each charge which is injected into the accumulator being recharged.

9. Apparatus as set forth in claim 8 in which said stroke adjustment mechanism comprises a stop, means for selectively positioning said stop axially along the direction of travel of the piston and abutment means on the piston for abutting said stop.

10. Apparatus as set forth in claim 9 in which said control means comprises means for sensing the abutment of said abutment means with said stop and for permitting the injection of a measured charge from said piston assembly during the recharging of a particular accumulator only if abutment of said abutment means with said stop has been sensed.

11. Apparatus as set forth in claim 9 in which said stroke adjusting mechanism comprises means biasing said piston in the direction to draw liquid from said reservoir and including a valve associated with said piston operable to allow a force greater than the bias force acting on the piston to cause the piston to inject a measured charge into the accumulator being recharged.

12. Apparatus as set forth in claim 11 including time delay means by which said first-mentioned valve is operated in a time delay relation to the switching of the particular accumulator being recharged from its on-line to its off-line status.

13. Apparatus as set forth in claim 12 in which said time delay means is also effective for causing venting of the headspace of the accumulator being recharged so that the valve associated with the piston is operated after the headspace of the accumulator being recharged has been vented.