712,072. Proportionate mixing of liquids; mixing appliances. CROWN CORK & SEAL CO., Inc. April 9, 1952 [May 18, 1951], No. 9145/52. Class 86 [Also in Group XXXV] A liquid proportioning apparatus comprises a plurality of pumps each fed from a separate source of liquid and having its outlet jointed to conduits adapted to deliver all of the separately pumped liquids to a mixing device. characterized by by-pass connections returning each pumped liquid to its source and a valve associated with each pump for alternatively delivering the pumped liquid to the mixing device or returning said liquid to its source, the valves for all of the pumps being connected for operation to deliver or return all of the pumped liquids. An apparatus for the proportionate mixing of water and syrup in the manufacture of soft drinks comprises two tanks 20, 22, Fig. 2 for water and syrup respectively, connected to water and syrup supply lines 36, 38 which include valves 44, 46 controlled by floats in the respective tanks so that the liquid 'levels in the tanks are maintained constant. Pumps 60, 62 which are preferably of the type which have a helical screw rotor revolving within a stator which has a double internal helical thread, are connected by flow lines 64, 66 to outlet pipes depending from the bottom of the tanks. The pumps are driven by a single electric motor 102. the pump 60 being directly coupled to the motor shaft and the pump 62 being driven through a variable speed mechanism 106 which effects gradual and uniform changes of speed when adjusted by means of a hand wheel 108 mounted on a control panel 94. The outlets of the pumps 60, 62 are connected by flow lines 68, 72 with three way valves 70, 74 which are operatively connected together so that the output of both pumps 60, 62 can either be directed through flow lines 76, 82 to a mixing device 78, or bypassed back to the tanks 20, 22 respectively, through by-pass lines 80, 84. The three way valves 70, 74 are connected to a hand operated control lever 90 having a handle portion 92 extending through an arcuate slot in the control panel 94. The mixing device 78 comprises a horizontal tubular casing 130 into which the water from the line 76 is delivered through the lateral limb of a tee fitting 128, and an inner coaxially disposed tube 132 into which the syrup is delivered through an enlarged portion 136 sealed into the tee fitting. The tube 132 has a closed end 134, a spiral vane 138, is mounted within the annular space between the tubes 130, 132 and a longitudinal row of relatively small discharge ports 142 is provided in the upper side of the tube 132 for discharging the syrup into the helical passageway 140 where it becomes mixed with the water in concurrent flow. In a modification of the mixer 78, Fig. 8 (not shown) for preparing pulpy beverages, the ports 142 in the tube 132 are replaced by a lesser number of ports of considerably larger cross section located in the under side of the tube 132. The mixer 78 discharges into a delivery line 146 which is provided with a back pressure valve 148. The line 146 is connected to a cooler or saturator, Fig. 10 (not shown). An analyzing and/or controlling instrument may be connected in the mixture delivery line to sample the mixture being delivered and/or automatically control the variable - speed mechanism 106 to automatically maintain the proportions of syrup and water within close limits. As described the analysing means comprises a chamber 270, Fig. 13, through which a small quantity of the mixture flowing in the delivery line 146 is by-passed. The chamber contains a submerged float 280 connected by several small chains 282 to the casing 270. A change in the specific gravity of the mixture alters the buoyancy of the float 280 and results in a vertical displacement of the float and a redistribution in the proportion of the weight of the chains 282 taken by the float 280 and wall 270 so that the float comes to rest in a position which indicates the specific gravity of the mixture. Means to render automatic the control of the speed change mechanism 106 includes a differential electric transformer 284, Fig. 14, having its windings located around the casing 270 and having a core 286 consisting of an element of high permeability magnetic material in the float 280. The change of inductance of the transformer in accordance with variations in the height of the float is utilized to actuate voltage responsive apparatus 294 by which means a reversible motor 302 is caused to run in one direction or the other when the specific gravity rises or falls beyond predetermined limits, the motor 302 adjusting the variable speed mechanism 106 so as to restore the proportions of syrup and water delivered by the pumps 60, 62 to within the required limits. The apparatus is operated by an automatic electric controller which is associated with pressure actuated switches which cause the motor to be switched off in the event of a failure of the liquid supplies to the pumps 60, 62 or in the event of a build-up of excessive pressure in the delivery line 146. Limit switches associated with the handle 92 of the three-way valves prevents operation of the motor if the handle 92 is not in either the delivery position or the by-pass position.