US3613714A

US3613714A - Mixing apparatus

Info

Publication number: US3613714A
Application number: US46052A
Authority: US
Inventors: Paul B Frank; Thomas R Mangan Sr; John C Mcfall
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1970-06-15
Filing date: 1970-06-15
Publication date: 1971-10-19
Anticipated expiration: 1988-10-19

Abstract

FOR PRESENT INVENTION IS DIRECTED TO A LIQUID-MIXING APPARATUS COMPRISING A FIRST CONTAINER AND A SECOND CONTAINER. Means is provided for supplying liquids to the containers with valve means arranged to control the supply of liquid to each of the containers. A liquid-level-sensing means is disposed in each of the containers which is arranged to control the respective valve means. Means is provided to selectively vary the position of each liquid-level-sensing means in the containers whereby the position of the sensing means in the first container is varied directly inversely to the position of the sensing means in the second container. A receiver means is arranged to receive the liquid from the first and second containers. And a control means is operably connected to the liquid-level-sensing means and the valve means whereby a preselected liquid mixture is continuously prepared.

Description

United States Patent [72] Inventors Paul B. Frank;

Thomas R. Mangan, Sr.; John C. Mcfall, all of Rochester, N.Y.

[211 App]. No. 46,052

[22] Filed June 15, 1970 [45] Patented [73] Assignee Oct. 19 197 l Eastman Kodak Company Rochester, N.Y.

[54] MIXING APPARATUS 9 Claims, 3 Drawing Figs.

[52] US. Cl 137/263, 137/391,137/392 [51] Int-Cl G05d 9/12 [50] Field of Search 137/263, 386, 391, 392; 73/304; 141/105, 107

[56] References Cited UNITED STATES PATENTS 2,457,903 1/1949 Kantor et a1. 137/263 X 3,181,557 5/1965 Lannan 137/391 3,428,072 2/1969 Welch 137/263 X Primary Examiner-M. Cary Nelson Assistant Examiner-David R. Matthews Attorneys-Walter O. Hodsdon and Robert L. Randall ABSTRACT: for present invention is directed to a liquid-mixing apparatus comprising a first container and a second container. Means is provided for supplying liquids to the containers with valve means arranged to control the supply of liquid to each of the containers. A liquid-level-sensing means is disposed in each of the containers which is arranged to control the respective valve means. Means is provided to selectively vary the position of each liquid-level-sensing means in the containers whereby the position of the sensing means in the first container is varied directly inversely to the position of the sensing means in the second container. A receiver means is arranged to receive the liquid from the first and second containers. And a control means is operably connected to the liquid-level-sensing means and the valve means whereby a preselected liquid mixture is continuously prepared.

PATENTEDUBT 19 l97| 3.613.714

SHEET 1 [IF 2 FIG: 2

PAUL B. FRANK THOMAS R. MA/V6AN,SR.

JOHN C. M FALL INVENTORS A TTOR/VEYS MIXING APPARATUS BACKGROUND OF THE INVENTION Many products and processes require the use of fluid mixtures which must be prepared immediately before use for incorporation into the product. Moreover, such products and processes often require that these fluid mixtures have variable component ratios to satisfy different product requirements. Various apparatus and methods of obtaining the desired mixtures and for providing relatively easy variation of the volumetric ratio of the components therein have been known.

One method of accomplishing this result has been to prepare as many differently ratioed mixtures as required and supplying them through a selector valve to the point of use. However, this method substantially increases the material inventory required, as well as multiplying the storage space necessary to maintain the stock of different solutions. Other arrangements have been devised for providing the necessary variable ratio solutions which use metering pumps in the supply lines of the mixture components. However, it has been found that apparatus utilizing such metering pumps does not provide the necessary accuracy or repeatability in the mixtures produced that is required for many processes. This results from the fact that metering pumps generally have the necessary accuracy either only at a specified flow rate or over a narrow range of flow rates whereby satisfactory mixture ratios are possible only within a limited range of ratios or at certain flow rates. Moreover, ithas been found that metering pumps can loose their accuracy after extended periods of use whereby the required mixture accuracy cannot be maintained. Still further, such metering pumps often must be operated continuously since the accuracy of these pumps is reduced when starting and stopping, as may be necessary for the intermittent supply of a fluid mixture.

It will thus be apparent that a simple and economic apparatus for continuously and/or intermittently preparing variable ratio mixtures would be desirable. Moreover, such a mixing and proportioning apparatus should operate at either lowor high-flow rates depending upon the requirements of the process while still maintaining the requisite accuracy of the mixture ratio. Such an apparatus should also be substantially automatic, incorporating the necessary safeguards to permit continued operation with relatively little operator attention. Moreover, if such apparatus utilizes no metering pumps, the accuracy of which can vary over a period of time, the attractiveness of the apparatus will be enhanced.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a liquid-mixing apparatus comprising a first container and a second container. Means is provided for supplying liquids to the containers with valve means arranged to control the supply of liquid to each of the containers. A liquid-level-sensing means is disposed in each of the containers which is arranged to control the respective valve means. Means is provided to selectively vary the position of each liquid-level-sensing means in the containers whereby the position of the sensing means in the first container is varied directly inversely to the position of the sensing means in the second container. A receiver means is arranged to receive the liquid from the first and second containers.

Further, the present invention includes a control means operably connected to the liquid-level-sensing means and the valve means whereby a preselected liquid mixture is continuously prepared.

More specifically, the present invention provides apparatus for mixing and dispensing a mixture of two liquids in a preselected volumetric ratio and comprises a substantially vertical support member and a fluid supply assembly for each of the liquids. A receiver container is mounted on the support member below the liquid supply assembled. Each liquid supply assembly comprises a liquid-measuring container mounted on the support member, a liquid conduit communicating with the bottom of the measuring container, means including an inlet valve communicating the liquid conduit to a source of the liquid, and means including an outlet valve communicating the liquid conduit to, and tangentially with, the lower portion of the receiver container. High and low liquid level probes are disposed in the upper and lower portions of each measuring container. A vertically movable probe is disposed in each measuring container. The receiver container is provided with a high liquid level probe and a low liquid level probe and an outlet means including a valve. A reversible drive means is connected to the movable probes through the top of the measuring containers and is arranged to simultaneously move the movable probes in opposite directions. A selectively settable counter means is arranged to automatically operate the drive means whereby the movable probes are located at a preset position. A control means is openly connected to the probes and the valves and is arranged, upon an indication of a low liquid level in the receiver container, to close the valve in the receiver container outlet means, to close the outlet valves from the measuring containers, and to open the inlet valves to the measuring containers. The control means is arranged, upon closing the circuit between a movable probe and the low level probe in a measuring container, to close the respective inlet valve and, upon closing both inlet valves, to open both outlet valves. The control means is also arranged, upon an indication of a low liquid level in a measuring container, to close the outlet valve from that measuring container and to open the inlet valve to that measuring container. The control means is funher arranged, upon an indication of a high liquid level in the receiver container to interrupt the filling cycle of the measuring containers after each of the inlet valves are closed and, upon an indication of a high liquid level in one of the measuring containers, to close the inlet valve s and to activate an alarm.

The various features of novelty which characterize the present invention are pointed out with particularlity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and the specific objects obtained by its use, reference should be had to the accompanying drawings and descriptive matter in which a preferred embodiment of the present invention is illustrated and described.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view, partially in section, of a preferred embodiment of the present invention;

FIG. 2 is a plan view of the preferred embodiment shown in FIG. 1; and

FIG. 3 is a schematic diagram of the control circuit of a preferred embodiment of the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT An elevation view of a preferred embodiment of the mixing apparatus of the present invention is illustrated in FIG. 1 and comprises a substantially vertically disposed support plate member 10 on which are mounted the components of the mixing apparatus. A liquid supply assembly is provided for each of the liquids to be mixed together. TI-Ie embodiment illustrated is arranged to prepare a mixture of two liquids, although an rangements for mixing three or more liquids utilizing the present invention are possible. Each of the two liquid supply assemblies includes a liquid-measuring container, 12 and 14, which in the preferred embodiment comprises a vertically elongated tubular member mounted on the front surface of the support plate 10. Preferably, the liquid-measuring containers are identical and have a relatively small horizontal cross section compared to the height thereof whereby any slight variation in the level of the liquid therein will have relatively little effect on volume of the liquid contained therein. Each of the liquid containers l2 and I4 is provided with a T- shaped liquid conduit, 16 and 18, communicating with the bottom thereof. One end of each conduit is connected to a source (not shown) of that liquid through a solenoid-operated inlet valve, 20 and 22. Each ofthe liquid-measuring containers is provided with an upper liquid-level-

sensing probe

24 and 26, and a lower liquid-level-sensing probe, 28 and 30. Vertically

movable probes

32 and 34 are arranged for movement in each of the liquid-measuring containers, the operation of which will be more thoroughly disclosed hereinafter.

A liquid-receiver container 36 is mounted on the front surface of support plate between and below the liquid-measuring containers l2 and 14. The liquid-receiver container is connected to each of the T-shaped

conduits

16 and 18, which are connected to the measuring containers, through

solenoidoperated outlet valves

38 and 40 via

lines

42 and 44. These lines, 42 and 44, enter the receiver container tangentially near the bottom thereof to facilitate and enhance the mixture of the liquids introduced therein. The receiver container is provided with an outlet line 46 in the bottom thereof which directs the liquid mixture through a solenoid-operated outlet valve 48 to a point of use, not shown. A high liquid level probe 50 and a low liquid level probe 52 are provided in the receiver container.

A drive means for operating the

movable probes

32 and 34 is mounted on the upper rear portion of the support plate member 10, as illustrated in the cutaway portion of FIG. 1. The drive means comprises a reversible probe-setting motor 54 which is connected through

shafts

56 and 58 to drive

assemblies

60 and 62, arranged to drive

vertical worm shafts

64 and 66 which are connected at the upper end to

movable probes

32 and 34 by

members

68 and 70, respectively. The

drive assemblies

60 and 62 are arranged so that as one probe is moved upwardly, the other probe is moved downwardly an equal distance. Thus, when probe 32 is in its lowermost position, as illustrated, probe 34 is in its uppermost position. A presettable counter assembly 72 is also driven by motor 54 through shaft 56 and is arranged to control the operation of motor 54. Accordingly, the operator can preset the solution ratio desired by means such as a dial or indicator lever (not shown) on the front face of support plate 10. Upon actuation of the system, the counter assembly operates the drive motor 54 to move

probes

32 and 34 to the position whereby the liquid levels in the liquid-measuring

containers

12 and 14 correspond to the preselected solution ratio. When the counter assembly reaches the preselected position, drive motor 54 is deenergized and the control system described hereinbelow and shown in FIG. 3 is automatically energized.

The control system itself and the manner in which it coacts with the rest of the apparatus will best be understood by describing the operation during a normal operating sequence. To commence operation, the operator activates the power switch S-l, supplying power down to point 74 which permits the operation of the probe-setting motor 54 and the presettable counter assembly 72. Indicator light 76 is also lit, indicating that the system is receiving power. To ensure that the various valves, relays, etc. are in their proper condition for the start of an operating cycle, a reset button S-2 is then pushed to momentarily close its contacts S-2a and S-2c and to open its contacts S-2b and S-2d. Contacts S-2a activate relay R-DN and drive motor 54, operating it in the direction to drive movable probe 32 to its lowermost position, and probe 34 to its uppermost position. Energization of R-DN will close its points R-DNa to maintain energization of the motor until such time as the probe 32 reaches its lowermost position, when microswitch MS-l is switched from the position shown to deenergize the motor and to activate the "ready light 78. Closing of the reset switch contacts S'2c also momentarily activatcs relay R-9 which closes its contacts R-9a and opens its contacts R-9b and R-9c. THe latter assures that the inlet valves and 22 are deenergized and closed. At the same time, contacts S-2c also energize

outlet valves

38 and 40 to assure that measuring containers l2 and 14 are empty. Relay R- 9 will he deenergized when the reset switch is released. The operator then sets the movable contacts in the counter assembly 72 to the desired liquid ratio and activates start" switch 8-4. The probe-setting motor 54 is thus energized to move probe 32 up and probe 34 down. At the same time, relay R-UP is energized opening contacts R-UPa to control the motor rotation direction and closing contacts R-UPb forming a holding circuit to continue the operation of the motor. The motor drives the movable probes and, simultaneously, the movable counter contacts 72 until they reach the preset position and close, activating relay R-6 which opens contacts R- 6a, deenergizing the motor 54, and closing contact R-6b activating the fill-refill portion of the control system.

When the fill-refill portion of the control system is thus activated, relays R-7 and R-8 will be energized, opening their contacts R-7c and R-Sc respectively to assure that

valves

38 and 40 are deenergized and are thus closed. At the same time,

solenoidoperated inlet valves

20 and 22 will be energized and opened through normally closed contacts R-Sa, R-lb and R- 9b, and R-Sa, R-2b, and R-9c, respectively. Accordingly, liquid-measuring

containers

12 and 14 are supplied with the respective liquid through

inlet valves

20 and 22. The first liquid-measuring container 12 is thus filled until thecircuit between the container 12 and the movable probe 32 is completed by the liquid therein, actuating relay Rl which closes its normally open points R-1a to form a holding circuit, and opens its normally closed contacts R-lb to dcenergize both solenoid-operated inlet valve 20 and relay R-7, shutting off the supply of liquid to measuring container 12. Likewise, the liquid-measuring container 14 is filled until the circuit between the container 14 and the movable probe 34 is completed by the liquid therein actuating relay R-2 which closes its normally open points R-Za to form a holding circuit, and opens its normally closed points R-2b to deenergizc both solenoid-operated inlet valve 22 and relay R-8, shutting off the supply of liquid to the measuring container 14. It will be appreciated that either liquid-measuring container can fill first, depending upon the mixture ratio and the respective liquid supply.

Relays R1 and R-2 remain activated, holding relays R-7 and R8 deenergized, until the liquid levels in the liquid-measuring containers l2 and 14 fall below the low level probes 28 and 30, respectively, as described below. When both relays R- 7 and R-8 are thus deenergized, solenoid-operated

outlet valves

38 and 40 are energized and opened, draining the liquid-measuring

containers

12 and 14 into the receiver container 36 via

lines

42 and 44. At the same time that

outlet valves

38 and 40 are opened, relay R-9 is reenergized, closing normally open points R-9a to form a self-holding circuit, keeping relay R-9 energized until both relays R-7 and R-8 are again actuated when relay R-9 is then deenergized. The

outlet valves

38 and 40 remain open until the respective circuits between low level probes 28 and 30 and the liquid-measuring containers l2 and 14 are opened when the liquid level in the respective container falls below that low level probe. At that time, relays R-1 and R-2 are deactivated, reenergizing relays R-7 and R8. When both R-7 and R-8 are energized, relay R-9 is dropped and contacts R-7c and R-Sc are opened to close

outlet valves

38 and 40. Upon inactivation of relay R-9,

inlet valves

20 and 22 are reopened to refill the respective liquid containers. This fill, empty, refill cycle continues as long as the demand for the liquid mixture continues.

When the liquid level in the receiver container 36 rises, completing the circuit between low level probe 52 and the container 36, relay R-4 is actuated, closing contacts R-4a to energize and open outlet valve 48, permitting the liquid mixture to flow to the point of use (not shown). As illustrated in FIG. 3, switch S-6 may be located at the point of use of the mixture to permit the manual opening or closing of the outlet valve 48.

If the flow of the liquid mixture to the point of use is substantially equal to the flow rate into the liquid-mixing apparatus, it will continue to cycle, filling the liquid-measuring containers to the preset level and then emptying the containers and mixing the liquids in the receiver container. If the liquid mixture use rate is greater than the capacity of the mixing apparatus, then the circuit between low level probe 52 and the receiver container 36 will open, deenergizing relay R-4 to close outlet valve 48. If the liquid mixture flow rate at the point of use is less than the capacity of the mixing apparatus, as is usually the case, the liquid level in the receiver container 36 will rise until the circuit between the high level probe 50 and the receiver container is completed, energizing relay R-3, opening contact R-3a actuating a time delay relay R-T, the contact R-Ta of which opens the circuit controlling outlet valves38 and 40 for a predetermined period. This time period may be selected according to the capacity of the mixing apparatus and the use rate of the system to which the mixture is supplied. Alternatively, the timer may have a manually variable time delay period which may be set by the operator according to the system characteristics. Upon expiration of the time delay period, contact R-Ta recloses and, providing the other conditions are met, the

outlet valves

38 and 40 are again opened to empty the fluid-measuring containers.

Relay R-S is connected to high level probes 24 and 26 in the liquid-measuring containers l2 and 14, respectively. Should a failure occur in one of the relays R-l or R-2, permitting one of the liquid-measuring containers to overfill, relay R-5 is energized, opening its contacts R-Sa to deenergize and

close inlet valves

20 and 22 and closing its contact R-Sb to activate a visual and/or audible alarm 80.

Accordingly, it will be seen that the present invention provides a substantially automatic mixing apparatus which will provide accurate, continuous delivery of a liquid mixture having any desired component ratio. Tl-le mixture component ratio can be easily selected to meet varying requirements. it will be appreciated that the respective liquid levels held in the liquid-measuring containers will provide a flow rate into the receiver container substantially proportional to the liquid mixture ratio whereby the mixture flowing into the receiver container has the proper mixture ratio at all times.

Moreover, it will be seen that, unlike systems utilizing metering pumps or other proportional flow devices, the present mixing apparatus can provide either a continuous or an intermittent supply of the liquid mixture with equal accuracy.

Still further, with the automatic mixer apparatus of the present invention, the liquid supply to the two liquid-measuring containers may be either continuous or intermittent and may be either a pumped supply or a gravity fed supply without affecting the accuracy of the mixture formed thereby.

in a preferred embodiment constructed in accordance with the foregoing description, a ball screw drive having a pitch diameter of 0.375 inch and a lead of 0.125 inch was used for the

drive assemblies

60 and 62 and for the

vertical worm shafts

64 and 66. A General Electric Presin" synchronous motor model U-280 was used for the drive motor 54. This motor has a speed of 75 rpm. and stops within of shaft rotation when the power is cut off. Accordingly, the mechanical accuracy of the probe-positioning portion of the apparatus is l part in 1,800 which gives an accuracy in the final liquid mixture of at least 0.5 percent, even at very extreme mixture ratios.

Alternatively, the present apparatus may be provided with a probe-setting motor and counterarrangement which eliminates the necessity of resetting the movable probe to a given position before the fluid mixture ratio desired may be set. It will also be appreciated that should the nature of the mixture components require, a mechanical mixer can be provided in the receiver container 36.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

We claim:

I. Liquid-mixing apparatus comprising a first container and a second container, means for supplying a first liquid to said first container, means for supplying a second liquid to said second container, valve means arranged to control the supply of liquid to each of said container, liquid level sensing means disposed in each of said containers arranged to control the respective valve means, means arranged to selectively vary the position of each liquid-level-sensing means in said containers whereby the position of the sensing means in said first container is varied inversely to the position of the sensing means in said second container, and receiver means arranged to receive the liquid from said first and second containers.

2. The invention according to claim 1 wherein a control means is operably connected to said liquid-level-sensing means and to said valve means, said control means arranged to operate said valve means in response to the liquid-levelsensing means to prepare a preselected liquid mixture.

3. The invention according to claim 1 wherein said valve means includes an inlet valve and an outlet valve cooperating with said first container and an inlet valve and an outlet valve cooperating with said second container.

4. The invention according to claim 1 wherein said means for supplying liquid to said containers includes a first fluid conduit communicating with the lower portion of the first container and a second fluid conduit communicating with the lower portion of the second container.

5. The invention according to claim 1 wherein said means arranged to selectively vary the position of the liquid-levelsensing means includes a drive motor and a presettable counter arranged to control said drive motor.

6. Apparatus for mixing and dispensing a mixture of at least two fluids in a preselected volumetric ratio comprising a fluid supply assembly for each of said fluids; a receiver container disposed below said fluid supply assemblies; each fluid supply assembly comprising a fluid-measuring container, a fluid conduit communicating with the bottom of said fluid-measuring container, means including an inlet valve communicating said fluid conduit to a source of said fluid, a high fluid level probe disposed in the upper portion of said measuring container, a low fluid level probe disposed in the lower portion of said measuring container, a vertically movable probe disposed in said measuring container, and means including an outlet valve communicating said fluid conduit to said receiver container; said receiver container having an outlet means including a valve; drive means connected to said movable probes arranged to selectively move said movable probes; and control means operably connected to said probes and said valves and arranged to close the outlet valves from said measuring containers and open the inlet valves to said measuring containers, said control means arranged upon closing the circuit between the movable probe and the low level probe in a measuring container to close the respective inlet valve and upon closing both inlet valves to open both outlet valves.

7. The invention according toe claim 6 wherein said fluid supply assemblies and said receiver container are mounted on and supported by a vertically disposed support member.

8. THe invention according to claim 6 wherein said fluidmeasuring containers are vertically extending tubular members which are arranged to permit movement of the vertically movable probe through the upper end thereof.

9. Apparatus for mixing and dispensing a mixture of two liquids in a preselected volumetric ratio comprising a substan' tially vertical support member; a liquid supply assembly for each of said liquids; a receiver container mounted on said support member below said liquid supply assemblies; each liquid supply assembly comprising a liquid-measuring container mounted on said support member, a liquid conduit communicating with the bottom of said liquid-measuring container, means including an inlet valve communicating said liquid conduit to a source of said liquid, a high liquid level probe disposed in the upper portion of said measuring container, a low liquid level probe disposed in the lower portion of said measuring container, a vertically movable probe disposed in said measuring container, and means including an outlet valve communicating said conduit to said receiver container; said receiver container having a high liquid level probe and a low liquid level probe, said conduit means communicating tangentially with the lower portion of said receiver container, said receiver container having an outlet means including a valve;

reversible drive means connected to said movable probes through the top of said measuring containers and arranged to simultaneously move said movable probes in opposite directions; selectively settable counter means arranged to automatically operate said drive means whereby said movable probes are located at a preselected position; and control means operably connected to said probes and said valves and arranged upon an indication of a low liquid level in said receiver container to close the valve in the receiver container outlet means and to close the outlet valves from said measuring containers and open the inlet valves to said measuring containers, said control means arranged upon closing the circuit between the movable probe and the low level probe in a measuring container to close the respective inlet valve and upon closing both inlet valves to open both outlet valves from said measuring containers, said control means arranged upon an indication of a low liquid level in said measuring container to close the outlet valve from said measuring container and to open said inlet valve to said measuring container, said control means arranged upon an indication of a high liquid level in said receiver container to interrupt the filling cycle of said measuring containers after each of the inlet valves are closed, and said control means arranged upon an indication ofa high liquid level in one of said measuring containers to close said inlet valves and to activate an alarm.

Claims

1. Liquid-mixing apparatus comprising a first container and a second container, means for supplying a first liquid to said first container, means for supplying a second liquid to said second container, valve means arranged to control the supply of liquid to each of said container, liquid level sensing means disposed in each of said containers arranged to control the respective valve means, means arranged to selectively vary the position of each liquid-level-sensing means in said containers whereby the position of the sensing means in said first container is varied inversely to the position of the sensing means in said second container, and receiver means arranged to receive the liquid from said first and second containers.

2. The invention according to claim 1 wherein a control means is operably connected to said liquid-level-sensing means and to said valve means, said control means arranged to operate said valve means in response to the liquid-level-sensing means to prepare a preselected liquid mixture.

5. The invention according to claim 1 wherein said means arranged to selectively vary the position of the liquid-level-sensing means includes a drive motor and a presettable counter arranged to control said drive motor.

8. THe invention according to claim 6 wherein said fluid-measuring containers are vertically extending tubular members which are arranged to permit movement of the vertically movable probe through the upper end thereof.

9. Apparatus for mixing and dispensing a mixture of two liquids in a preselected volumetric ratio comprising a substantially vertical support member; a liquid supply assembly for each of said liquids; a receiver container mounted on said support member below said liquid supply assemblies; each liquid supply assembly comprising a liquid-measuring container mounted on said support member, a liquid conduit communicating with the bottom of said liquid-measuring container, means including an inlet valve communicating said liquid conduit to a source of said liquid, a high liquid level probe disposed in the upper portion of said measuring container, a low liquid level probe disposed in the lower portion of said measuring container, a vertically movable probe disposed in said measuring container, and means including an outlet valve communicating said conduit to said receiver container; said receiver container having a high liquid level probe and a low liquid level probe, said conduit means communicating tangentially with the lower portion of said receiver container, said receiver container having an outlet means including a valve; reversible drive means connected to said movable probes through the top of said measuring containers and arranged to simultaneously move said movable probes in opposite directions; selectively settable counter means arranged to automatically operate said drive means whereby said movable probes are located at a preselected position; and control means operably connected to said probes and said valves and arranged upon an indication of a low liquid level in said receiver container to close the valve in the receiver container outlet means and to close the outlet valves from said measuring containers and open the inlet valves to said measuring containers, said control means arranged upon closing the circuit between the movable probe and the loW level probe in a measuring container to close the respective inlet valve and upon closing both inlet valves to open both outlet valves from said measuring containers, said control means arranged upon an indication of a low liquid level in said measuring container to close the outlet valve from said measuring container and to open said inlet valve to said measuring container, said control means arranged upon an indication of a high liquid level in said receiver container to interrupt the filling cycle of said measuring containers after each of the inlet valves are closed, and said control means arranged upon an indication of a high liquid level in one of said measuring containers to close said inlet valves and to activate an alarm.