US2775205A - Device for automatically refilling tanks - Google Patents

Description

Dec. 25, 1956 A. GUNTHER DEVICE FOR AUTOMATICALLY REFILLING TANKS Filed Jan. 24, 1952 3 Sheets-Sheet l j Arnoldo Gunfher BY Maxwell E.S parrow ATTORNEY,

Dec. 25, 1956 A. GUNTHER DEVICE FOR AUTOMATICALLY REFILLING TANKS Filed Jan. 24, 1953 3 Sheets-Sheet 2 m A A 6 2 2 1 F a 4 2 I w B w H B O o 3 M V 9 2 a 7 t 5 2 l #44 PWV INVENTOR.

Arnaldo Gun'rh'er MoxwellE.Sporrow.

ATTORNE).

Dec. 25, 1956 A. GUNTHER 3 1 DEVICE FOR AUTOMATICALLY REFILLING TANKS Filed Jan. 24, 1952 3 Sheets-Sheet 3 INVENTOR. -Ar.nold0 Gunther Maxwell E Sparrow- ATTORNEY.

United States PatentO DEVICE FOR AUTOMATICALLY REFILLING TANKS Arnoido Gunther, Buenos Aires, Argentina Application Ilanuary 24, 1952, Serial No. 268,057

3 Claims. (Cl. 10325) The invention relates to a device for automatically refilling tanks. For this purpose the device starts an electromotor which, in turn, starts the corresponding pumping device, as soon as the level of the liquid contained in the tank drops to a given level, and stops again said electromotor, as soon as, due to pumping, a given level, higher than the first mentioned, is reached.

The device may be used with equal efficiency for all sorts of liquids, provided these liquids are not miscible nor able to react chemically with mercury at room temperatures. Also the tank is of no importance, as the device can be adjusted easily to any particular kind of tank. The location of the device is completely independent of that of the tank, viz it may be placed wherever desired, as for instance near the pumping unit to minimize the cost of the electrical wiring connections. Furthermore, as the device does not have moving elements submerged in the liquid of the tank, there does not exist any danger of corrosion. Also the harmful interference of solid particles, such as sand carried by the liquid, which frequently stop the automatic action of the usual floats, is avoided, as will be seen hereafter.

One of the many uses of the device is in connection with water tanks installed upon the top of buildings for offering a supply of running water throughout the building and with such an installation in mind the invention will now be explained and described with reference to the accompanying drawings wherein:

Fig. 1 is a perspective view of the apparatus, showing also the principal device and the tank to be automatically controlled, in one of their preferred realizations;

Fig. 2 is a vertical section along line 22 of Fig.1;

Fig. 3 is a vertical section along line 3-3 of Fig. 1;

Fig. 4 is also a vertical section along line 2-2 of Fig. l, but with certain elements of the apparatus shown in another position; and

Figs. 5, 6, 7 and 8 are details which will be explained hereafter.

Referring now to the drawings, the numeral 1 indicates a box fixedly containing therein the different elements which will be specified hereafter. Numeral 2 indicates a smaller box containing one or several electrical mercury switches 3. Numeral 4 indicates a bar which passes through perforations effected in lugs 5 and 6 of box 2. Bar 4, lugs 5 and 6 and box 2 with the contents thereof are rigidly connected together. Bar 4 is eccentrically inserted in a solid cylinder 7.

Triangular rods 8 and 9 are rigidly inserted in bar 4. The lower edge of rod 8 rests with the extremes thereof in two opposed perforations of element 10. Element 10 has the shape of an inverted U. It is fixed to the top of box 1. Rods 11 and 12 are fixed to the top of box 1 and, by abutting against box 2, their movement will be limited thereby. The numeral 13 indicates a cylindrical chamber formed by the following elements: Two circular discs 14 and 15, these discs being made of a rigid material, such as iron, ebonite, etc; a solid cylinder 16, preferably of a light material such as ebonite, rubber,

wood, etc., placed between both discs 14 and 15, the diameter of said cylinder being somewhat smaller to that of the discs and provided with one or several channels made in the bases thereof and extending along the diameters; a tube 17 of some elasticand easily extensible material, such as rubber; and two clasps 1S and 19 which fix tube 17 hermetically upon discs 14 and 15.

Chamber 13 depends from rod 9 by means of plates or braces 20 and 21. These braces are perforated at their upper part and rod 9 passes through said perforations. Said braces 20 and 21 have been conveniently curved so as to coincide with the external surfaces of discs 14 and 15 upon which they are fixed by soldering or otherwise.

Disc 14 is provided with a perforation in the center thereof to which is fixed the cock of air outlet 22. Also disc 15 is provided with a perforation in the center thereof to which is fixed curved tube 23 which continues in a flexible tube 24. Tube 24 continues in tube 25. Tube 25 is divided into two sections by cock 26. Cock 26 is adapted to shut or open, as the case may be, the mercury passage through tube 25. Tube 25 is provided with two branches 26 and 27 which respectively continue in tubes 28 and 29. These tubes may be made of rubber, of rubber and cloth, of plastic or similar material. Between the opposed extremes of tubes 28 and 29 another tube 30 is inserted which has a very small, practically capillary, interior diameter. Tube 25 extends externally to box 1 in tube 31. The total length of this latter tube 31 varies and is adjusted according to the requirements of each case, as will be seen hereafter.

The numeral 32 indicates a hermetical chamber which is constructed in a material resistant to pressure, such as iron or the like. It is slidable along rail 33 by means of a groove provided in said rail and a screw 34, the head of which abuts in its inner part against the edges of the groove. Screw 34 passes through the perforation effected in the lug or flange adhered rigidly to the chamber.

For fixing the chamber, the nut which turns upon screw 34 is screwed on. The upper base of said chamber is perforated at the center thereof. Into said perforation the cock of air vent 35 is inserted. Also the lower base is perforated and inserted therein is a tube 36 which is a continuation of tube 31. From the left lateral wall of the chamber parts, tube 37 which continues in a flexible tube 38 and terminates in bent tube 39. Tube 39 penetrates into supply pipe 40. It is placed in such a position as to present its opening perpendicularly to the flow of the liquid current produced by pump 46. The adhesion of bent tube 39 to supply pipe 40 is effected by usual means, such as soldering, screwing, etc.

A tank 41 is provided which is controlled automatically. Tube 42 connects the liquid of tank 41 with supply pipe 40. Tube 42 is connected with supply pipe 49 and tank 41 beneath the level which has been chosen as the lowest to be allowed in the tank, viz. low level 43. 45 is the discharge tube for the liquid in the tank. The drawings show a centrifugal type pump 46 operated by an electromotor 47. Pump 46 is provided with intake tube 48 and a retention valve 49 interposed in this tube which only permits the passage of liquid in a progressive direction from the inlet to the outlet.

If it is intended to use a piston pump, said retention valve would not be necessary, as the pump itself is already provided therewith in its chamber. 50 is a box for the electric connections wherein will be effected the connections between the wires of the motor line, those of the mercury switches and those of the electromotor in the usual manner, the numeral 51 indicating the wires of switches 3 which preferably have great flexibility.

Figs. 1 and 2 show the condition during the correspond ing discharge phase of the tank, viz. when the level of the water drops from a high level 44 to a low level 43. During this descent which is effected at low speed, the water level contained in pipe 40 is at the same horizontal plane as that of the tank, as both communicate with one another through tube 42. Pressure at any one point of supply pipe 40 will, therefore, be equal to the weight of the liquid column at a vertical height comprised between the water level in the tank and the considered point, the straight section of this column being everywhere exactly the same, and equal to the surface unit. Chamber 32 contains two different liquids, which do not mix, viz. mercury 52 at the bottom, and water 53 which occupies the remainder of the chamber. Tubes 36, 31, 25, 24, 23, 26, 27, 28, 29 and 30 as well as the free inner space of chamber 13 defined or limited by the inner surface of tube 17, the outer surface of solid cylinder 16 and the oppose faces of discs 14 and 15 are filled with mercury.

Supposing, for instance, that the whole free space just defined by chamber 13 would be limited by rigid surfaces which pressure cannot deform, the pressure upon the separation surface of both liquids in chamber 32 would be that created by a vertical mercury column of straight section equal to the surface unit and of the same height as that comprised between the base of disc 14 and the just referred to separation surface.

In the present case, as tube 17 is of an elastic and easily extensible nature, to the supposed previous pressure must be added that exercised upon the mercury by tube 17. As the thickness of tube 17 is small in comparison with the other dimensions, it may be considered as an elastic membrane and the deformations thereof will consist in variations of the area of this membrane. This is to say that the material of tube 17 has practically no shape-elasticity, viz. that it does not offer any resistance to a deformation which does not modify the area thereof. More precisely, every fiber of the membrane is only subjected to tensions which operate along it, viz. that the stresses have at any point of the membrane the direction of the tangent to the surface at said point. To an increase of the volume of mercury contained within the free space of chamber 13 corresponds, due to the non-compressibility of the mercury and of all the bodies whose surfaces limit said space, an elastic deformation of the membrane which increases the area thereof. The pressure which the membrane applies now to the mercury contained therein is greater than before said deformation.

If the dimensions and the material of the membrane are chosen conveniently, relatively small pressure increases can be obtained for greater deformation. in other words, the increase of the free space and therewith the increase of the weight of the mercury contained therein may be caused to be relatively great with regard to the weight prior to the considered deformation for a relatively small pressure increase, also with regard to the pressure applied by the membrane prior to deformation. The vertical distance between the separation surface of the liquids in chamber 32 and the inner surface of disc 14 has been selected such that the pressure created by the mercury column and the pressure of the membrane or tube 17 equalizes the water pressure upon the same mentioned separation surface, when the free level thereof in the tank coincides with low level 43. The state of tension of the membrane may be any place far below that which corresponds to the breakage thereof. Therefore, with water occupying the tank up to level 43, there does not exist any flow of liquid, as the whole mercury-water system is in equilibrium.

There now will be considered the forces which operate upon the lever bar 4, the lower edge of rod 8 being the turning axis thereof. Figs. and 6 show said forces schematically, Fig. 5 corresponding to the condition shown in Figs. 1 and 2, and Fig. 6 corresponding to that of Fig. 4.

Force A is derived from the weight of chamber 13 with its accessories and mercury contents. The fraction of the weight of flexible tube 24 with its mercury contents, suspended upon its left support, and tube 23, are comprised in A, whereas the rest of the weight is cancelled by the reaction of the right support or tube 25. The application point of said force A resides at the upper edge of rod 9 which is rigidly connected to bar 4. Force B corresponds to the weight of box 2 with its contents, with the exception of the weight of the movable mercury of switches 3. The fraction of the weight of wires 51 which acts upon box 2 is supposed to be included, as well as the weight of cables 55 and 56, practically devoid of any resistance to flexibility. Their function will be explained later on. The application point of B force resides at the center of gravity of all mentioned masses and it has been arranged in such a way that said center will remain above the horizontal plane which contains the turning axis. Force C is the movable mercury 5'4 of switches 3, the application point thereof being the center of gravity of said masses. Force D is the weight of solid cylinder 7 rigidly united to bar 4. The application point thereof resides at its center of gravity. Force E is the weight of bar 4 and the rods connected therewith.

All forces above specified vary their application point during a turn of the lever which carries it to the position shown in Fig. 6. Supposing that the intensities and the line of the forces shown in Fig. 5 have been chosen in such a way that the resulting force R of all of them passes through the turning axis, after the turn, as shown in Fig. 6, the resultant force R will be displaced to the right of the axis. In order to now obtain displacement of the resultant force R again to the left, and so that its line passes again through the axis, the intensity of force A will have to be increased to a given value A.

The functioning of the apparatus will now be explained. After having selected the place where the apparatus will be located, the approximate vertical distance between the predetermined low level in the tank and the selected place for the apparatus will be measured. Assuming that the liquid of tank 41 is water, this distance will be divided by 13.6 which is approximately the specific weight of mercury, and rail 33 will be positioned such that the center thereof remains in a horizontal plane which is distant from the inner surface of disc 14 just the length obtained by said division. Thereafter, the connections between supply pipe 40 and chamber 32 will be made, as well as the connection between said chamber and tube 25, which is done by means of flexible tube 31. Supposing that tube 42 has been placed between the supply pipe and the tank, the latter will be filled to the low level. Pipe 40 will then be occupied with water up to level 43. Chamber 32 contains now all the necessary mercury. When cock 35 is opened, water will penetrate into said chamber and expel the air contained therein. When water begins to run out through said cock, it will be closed. Cock 22 is now opened and cock 26 with its passage will also be left open. The pressure which the Water applies upon the mercury, causes it to climb up and fill tubes 32, 31, 25, 27, 29, 30, 28, 26, 24 and 23 and the free space of chamber 13, expelling the air therefrom. When the first drops of mercury flow out of cock 22, this too will be closed. As, when chamber 13 is empty, the position which it occupies being that shown in Fig. 4, by a manual effort put upon it it will be compelled to remain in the position shown in Figs. 1 and 2, until it remains in said position when filled with mercury. In the event that insufficient mercury enters therein, then chamber 32 is raised until the mercury is sufficient. All the weights which act upon the previously defined lever, are disposed and selected in such a way that, for a given quantity of mercury in chamber 13, the resultant of all of the weights passes through the turning axis. In order to accomplish this, chamber 32 is caused to slide gently downwards until at a given position thereof, the lever starts its clockwise rotation movement. Chamber 32 is then raised again very slowly and for a very short distance and it will then be fixed permanently in said position.

Thus, equilibrium between the liquid columns of mercury and water is attained. The increase of the height of the mercury column when lowering chamber 32 has as a consequence a diminution of the contents in chamber 13, so as to re-establish the equilibrium, since as it has been explained before, the pressure created by said column is the sum of two pressures, viz. that created by the weight of a mercury column of a straight section equal to a surface unit, the height being equal to the vertical distance between the inner face of disc 14 and the separation surface 5253; and that created by the pressure applied by membrane or tube 17. As the pressure created by the water column did not vary during all the foregoing operations, the sum of both pressures has to remain constant, and if one, the column, increases, the other one, the pressure of the membrane, will diminish.

Therefore, a certain quantity of mercury will flow out of chamber 13 and will flow to 3-2. The area of the separation surface between mercury and water in said chamber has been made sufficient so that a small variation of the volume of mercury contained therein will create only an insignificant variation of the height thereof. If the contrary would happen, when a small volume passes from chamber 13 to chamber 32, the total height of the mrecury column would be greatly diminished and then mercury would not continue to flow from chamber 13 to chamber 32. The reasons are evident.

When chamber 32 is thus installed at its selected place, a small descent of the water level beneath the low level will cause a diminution of the volume of mercury contained in chamber 13. Resultant force R will, therefore move to the right and the lever will turn in a clockwise direction until box 2 abuts against rod 11, when it will then be in the position shown in Fig. 4. The mercury 54 of switches 3 having been displaced to the right, the electric circuit is closed, electromotor 47 started and pump 46 put in operation.

As heretofore stated, the application points of all forces have been selected in such a way that they move to the right during the turn of the lever, whereby the resultant moment of all forces with regard to the turning axis will increase with the turned angle, Which on the other hand causes an increase in the angular rotation speed, whereby a rapid closing of the electric circuit will be attained.

During the whole discharge phase of the tank, viz. during the time the water level descends from high level 44 to low level 43, chamber 13, as it contains more mercury than what corresponds to level 43, will maintain bar 4 in the position of Figs. 1 and 2. In this position the electric circuit is open and, therefore, during this phase the pump will not work.

When bar 4 turns a fraction of the total angle of the complete rotation, cord 55, fixed at one of its ends to box 2 and at the other of its ends to one of the arms of cock 26, will be under tension. From this moment it begins to draw the arm of the cock, causing it to describe an angle. When box 2 abuts against rod 11, the passage of the cock will be closed. In this way, any flow of mercury between chambers 13 and 32 will be compelled to pass through capillary tube 30; that is to say, any flow of mercury has to now follow the channels defined by tubes 36, 31, tube 25 to branch 27, tubes 29, 30, 28, 26, part of tube 25 comprised between 26' and 24, tubes 24 and 23.

There will now be explained the functioning of the apparatus during the filling phase of tank 41, for which purpose reference will be made to Figs. 4, 5, 6, 7 and 8.

The pump begins to work when the water level drops to low level 43. The suction created thereby will open the retention valve and water will flow through admission tube 48 to supply pipe 40. In the present case, by way of example, the pump is of the centrifugal type. The flow created by this type of pump is rather uniform, that is, the speed of the liquid through a section of the admission tube and/ or supply pipe is practically constant as time passes. The pressure which operates upon the inlet of bent tube 39 may be considered to be approximately the sum of two pressures: the static one and the dynamic one. The first one is identical at any plane which passes through a given point of the liquid, supposing this point to be fixed in space. In fluids which are incompressible, the pressure which is exercised in any direction is independent of said direction. The dynamic pressure, sometimes called the velocity head, depends fundamentally from the angle formed by the considered plane and the direction and sense of the vectorial speed of the fluid. Its maximum value is reached for the plane which extends perpendicularly to the direction of the vectorial speed, and taking into account the pressure which operates upon the surface of the plane in front of the current. To these just now mentioned two pressures, must be added in practice the so called charge loss which is the necessary pressure for causing the fluid to circulate, overcoming different resistances, such as: the friction at the limits of the layers, viscosity, turbulences etc. The total sum of these three mentioned pressures which act upon the inlet of tube 39 is greater than the hydrostatic pressure created by the water column, supposed to be fixed or motionless, comprised between said inlet and the high water level.

It has been said heretofore that, when bar 4 is in the position of Fig. 4, the resultant R of all operating forces was displaced to the right of the turning axis and that, so as to obtain again the displacement in an inverse sense, force A has to be increased.

The pressure excess which exists now at the inlet of tube 39, tends to create a displacement or a fluid flow in the sense of the pressure excess. Therefore, the mercury will flow from chamber 32 to chamber 13, passing through the tubes which have been mentioned above.

Capillary tube 30 will only permit the passage of a determined quantity during a given time.

As is known, the volume which passes therethrough, is proportional to time, to the diflference of pressures between the corresponding extremes of the capillary, and inversely proportional to the length thereof and to the diameter raised to the fourth power, as well as to the viscosity of the fluid. After a certain time which depends from the just now stated parameters, a suflicient quantity of mercury went into chamber 13 so as to cause bar 4 to turn, this time in a sense which is counterclockwise. During this turn, mercury 54 of the switches will flow to the left, will thus open the circuit and the pump will stop.

Cable 56 will act upon the right arm of cock'26' and will open it, in the same fashion as explained above about cable 55. So as to size capillary tube 30, in ac- .cordance with each particular case, in practice the following manner will be adopted:

The time will be measured which passes, with a given capillary tube, from the moment when the pump starts, to the moment when it is stopped by the turn of bar 4. Now will be measured the fraction of the total water volume comprised between levels 43 and 44, which entered into tank 41 during this time. If the measured fraction is l/n, n being greater than the unity, the given capillary tube will be withdrawn and will be replaced by another one of the same diameter, but of a length which is n times more.

Indeed, what interests here, is that the charging time of the tank coincides with the charging time of chamber 13. One of the ways of getting this coincidence is the indicated one, but there exists others; thus, for example, when the volume is known which passes through the given capillary tube during the time needed to get lever 4 again to its initial place, as shown in Figs. 1 and 2, it is very easy to find the sizes of the other capillary tube, of a different diameter to the first one, which enables the passage of this same volume during a time which is n times greater.

The object of cook 26' is to offer a passage of a relativel great section to the mercury which comes from chamber 13 during the discharge phase of the tank. in this fashion the pressure drop through tubes 23, 24, 25, 31 and 36 is insignificant and the chamber follows rapidly the descents of the level in tank 41. It must be kept in mind that there exist other solutions for this question and Fig. 8 shows one of them.

As may be seen there, capillary tube 557 is associated with tube 39. This tube 39 is now provided with a retention valve 58, which closes the passage for fluid when the pressure at the left side thereof increases due tothe impulsion of liquid in the tank. Then only the passage through capillary tube 57 remains open and the action is similar to the one stated above. As will be noticed, this type of disposition of a capillary tube does away with the necessity of cock 26' and cables 55 and 56, as well as the tubes 26, 27, 2E 29 and 30.

If the construction of Fig. 1. has been preferred, because of the fact that with this disposition of the capillary tube, it is first subjected to lesser inner pressures, then, as the variation of the viscosity with temperature is considerably less for mercury than for water, oscillations in the originally chosen levels 43 and 44 will be avoided as much as possible.

As may be deduced from what has been heretofore explained, chamber 13 does not need to be necessarily cylindrical. as the same object will be attained with an elastic cover of any other shape, for example a spherical globe entirely constructed in an easily extensible and elastic material connected and suspended by convenient means.

The solid cylinder 16 placed within chamber 13 has only the purposes of cconomizing mercury, and to cause the counterweights, viz. solid cylinder 7, to be lighter, as the function accomplished by tne chamber is the same with said solid cylinder or without it.

What I claim is:

1. A device for automatically refilling liquid containing tanks, said device comprising a hermetic chamber containing liquid of the tank in the upper part and mercury in the lower part, a duct between the upper part of said hermetic chamber and a tank supply pipe, a downwardly bent end on said duct and projecting into said supply pipe for detecting pressure changes therein, a connection tube opening into said tank below the lowest liquid level and connected to said supply pipe, a second chamber provided with extensible, resilient walls, a second duct between the lower part of said first chamber and said second chamber, an oscillatory bar from which said second chamber is suspended, mercury switches operatively associated with said bar, and a pump operatively connected to said mercury switches for actuation thereby, whereby said pump is automatically actuated upon a reduction in pressure in said supply pipe to refill said tank.

2. A device for automatically refilling a liquid con taining tank, said device comprising a hermetic chamber containing the tank liquid in the upper part and mercury in the lower part, a duct between the upper part of said hermetic chamber and a tank supply pipe, at downwardly bent end on said duct and projecting into said supply pipe, a connection tube under the lowest liquid level in said tank between said supply pipe and tank, a second chamber provided with elastic, extensible walls, a second partially flexible duct between the lower part of said first chamber and said second chamber, a valve connected in said second duct, a capillary by-pass in parallel with said valve, an oscillatory bar from which said second chamber is suspended, a fixed axis supporting said oscillatory bar, two cables fixed to said oscillatory bar and operatively attached to said valve, 21 box supported by said oscillatory bar, mercury switches contained in said box, and a pump operatively connected to said mercury switches for actuation thereby, whereby said pump is operative in response to reduced pressure in said supply pipe detected by said first duct end.

3. A device for automatically refilling a tank, said device comprising a chamber having extensible walls, means movable around an axis and supporting said chamber, a second chamber having rigid walls, connection means between said second chamber and a supply duct of the latter being in communication with said tank, said connection means having one end extending into said supply duct and bent towards the flow of liquid for detecting pressure variations in said supply duct, a retention valve in said connection means, a by-pass in parallel with said retention valve, a connection tube between said supply duct and tank, said tube being disposed beneath the lower level of tank liquid, a partially flexible duct between said elastic and rigid chambers, mercury contained within the lower part of said rigid chamber, the last named duct and elastic chamber, and mercury switches connected to said movable means for closing and opening operation upon movement of mercury into and out of said extensible chamber.

References ited in the file of this patent UNITED STATES PATENTS 1,794,962 Johnson Mar. 3, 1931 1,972,812 Woolley Sept. 4, 1934 2,013,576 Palmer Sept. 3, 1935 2,430,257 Teeson Nov. 4, 1947 2,462,076 Dryden Feb. 22, 1949 l i l l

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