US2635546A - Pump control - Google Patents

Description

April 1953 H. F, ENYEART ETAL 2,635,546

PUMP CONTROL Filed Jan. 5, 1949 2 SHEETS-SHEET 1 INVENTORS. H/IEOLD 1 f/VYELQT April 21, 1953 H. F. ENYEART ETAL 2,635,546

PUMP CONTROL Filed Jan. 5, 1949 2 SHEETSSHEET 2 l gig-1529mm...

an j 56 a2 INVENTORS.

70 #42040 E ENYE'AET 2 HERBERT W. KAA TZ ATTUENEYS.

Patented Apr. 21, 1953 PUMP CONTROL Harold F. Enyeart and Herbert W. Kaatz,

Elyria, Ohio I Application January 5, 1949, Serial No. 69,334

This invention relates to pumping systems, the control or controls therefor, and the methods of operating them.

One of the objects of the invention is to pro.- vide a pumping system and method of operating it that will be of general usefulness where a system responsive to the level of liquid, usually the liquid to be pumped, is employed; for example, in a sump or in the bilge of a ship. Another object is to provide a system and method of operating it that may advantageously be used where an installation is desired that is responsive to the presence or absence of a liquid under pressure. Another object is to provide a system and method of operating it that becomes efiective upon the occurrence of one and remains in effect during the continuance of the other of these conditions.

A further object of the invention is to provide a pump control that makes it possible, in a limited space, to use two or more pressuresensitive members responsive to different conditions in actuating and/or deactuating a pump. A further object is to provide such a control in which the action of one pressure-sensitive member augments that of another during part of the cycle of operations. A further object is to pro vide a control of this kind in which one pressure-sensitive member restricts operation of another to conditions exceeding an operational threshold and, upon manifestation of a tendency to reversal, overrides it. A further object is to provide a pump control having the indicated characteristics in which deactuation of the pump can occur only in the event that neither pressure-sensitive member is stimulated to activity by existence of the condition or conditions to which it is responsive.

Still another object of the invention is to provide, in a control system, a compact control unit of general application characterized by low height and small mass comprising an actuating chamber, means for admitting air under pressure to the actuating chamber, and a skirt-like portion for entrapping and placing under pressure the air so admitted. Still another object is to provide, in a singe housing, a control comprising a micro-switch, an actuating chamber defined by two diaphragms of like dimensions but of difierent efiective areas, one of them in proximity to the switch, and a spacer within the chamber for transmitting to the switch a force or forces applied externally of the chamber.

Still other objects include the provision of methods and means making possible economic,

Claims. (o1.'103 12) 2 efiicient, compact, rugged, long-lived units and systems of the kinds described.

In the accompanying drawings, from which, taken with the detailed description which follows, other objects and advantages will become apparent, Figure 1 represents a fragmentaryperspective of the bilge of a vessel showing a pumping system of a kind to which the invention relates' Figure 2 represents a central vertical section, with parts in elevation, of the control unit appearing in Figure 1. Figure 3 represents an exploded perspective, looking upward, of the control unit shown in section inFigure 2. Figure 4 represents a wiring diagram of a circuit that may, if desired, be employed in the system illustrated in Figure 1 and with the control unit illustrated in Figures 2 and 3.

As shown in Figure 1, the hull l of the vessel in which the pumping system is employed carries on the bottom or in the bilge thereof a bilge pump 2 provided with inlets 3 and a liquid discharge outlet 4. This pump may conveniently be of the typeshown, described and claimed in Enyeart and Kaatz application Serial No. 18,347, filed April l, 1948, for Pump; however, any other type of pump capable of drawing in bilge water, preferably at or near the base of the pump, and discharging it in the form of a stream through an outlet may be employed in lieu of that disclosed in such application. Connected to outlet 4 is a discharge line 5 which carries the bilge water through a discharge port fitting 6 located at a point above the water line. In discharge line 5 is a mounting T 1 which, for convenience an illustration, is shown as having its side connection at a level above that of its straightthrough connections, but which, in practice, may equally well be mounted at an angle of to that shown in order that the side connection and straight-through connections may all be at the same level. Mounted on or connected to such side connection is pump control unit 8, hereinafter described, from which project the leads 9 forming part of the electric circuit illustrated in Figure 4.

As indicated in Figure 2, control unit 8 consists in general of three principal parts; namely, a bell-shaped top section Ila, a generally annular middle section Nb, and a skirted bottom section He, the three taken together making up a three-part housing. Between top section Ha and middle section lib is an upper diaphragm l2; between middle section Nb and skirted bottom section He is a lower diaphragm l3 of like dimensions but of somewhat diiierent construction. By means of diaphragms l2 and I3, control unit 8 is in effect divided into an upper chamber or space M in top section Ha, a middle chamber or space l between diaphragms l2 and i3, and a lower chamber or space IS in bottom section He, the latter space serving as an air trap as hereinafter described.

Referring now to top section Ha and to Figures 2 and 3 of the drawings, a mounting flange 29 marks the lower limit of top-sectiow H a, such flange being machined on its bottom face and:

provided with a series of screw holes for the screws which hold top section Ha to the other sections which make up the three-part housing On the opposite side of top section i la is air-upstanding internally threaded collar-.21, the same.-

switch is biased toward a position in which the. circuit is open. By a force acting upward against switch button 25, the circuit may be closed so long as such force continues to be exerted; in its absence, the switch returns to open position and button 25 moves to the position which it occupied before the force was applied. 7

Below and withinthe limits of collar 2! is a circular opening 26 in the upper portion of top. section Ila, the same being provided for thedual' purpose. of permitting leads ll to pass therethrough and venting space ldlto the atmosphere. These ends are accomplished by providing a breather tube 2'! of relatively stiff rubber or other suitable material which extends to a point above any level likely to be reached by li uidlv collecting in the bilge of' the vessel, usually, but not necessarily, a point approximately at the level of discharge port fitting 5-. Breather tube 21 is provided with a reinforcing grommet 28 expanded in place inside the lower. end of breather tube 2? to prevent collapse of the breather tube under abnormal conditions. Surrounding opening I6 in the upper portion of top section Ha is a stepped portion 29 in which is seated'a tightly-fitting flexible gasket 3!) of a size such as to enable it' to bear against the outer walls of breather tube 2?. Such gasket 36 is surmounted by a rigidwas'he'r 3! and by an externally threaded follower plug 32 fitting the threads inside collar 2i. Follower plug. 32 may be moved into or out of place, as the case. may be, by means of a hexagonal nut 33 on the outer end thereof and, when moved into place, acts through washer 3| to place a forceon gasket 36 tending to expand the same into water-tight relation to breather tube 21.

With the exception of stepped portion 29, these parts are shown in exploded fashion along breather tube 2f near the top of Figure 3..

Glued to the top side of upper diaphragm I2 is a rigid reinforcing disc 35 surrounded by a raised flexing portion or corrugation 36 formed in the diaphragm itself; Upper diaphragm I2 is provided near its periphery with a series of holes conforming in position, size and number to the holes in flange 2d of top section Ila, the purpose of such holes being to accommodate the screws which hold together the three parts of the housing. Lower diaphragm 1.3 is of the same dimensions as and generally similar in construction to upper diaphragm I2, having a rigid reinforcing disc 31 glued to the top side thereof and, surrounding such disc, a raised flexing portion or corrugation 33, both disc 3? and corrugation 38 being of considerably smaller diameter than the corresponding parts of upper diaphragm l2. Overlying lower diaphragm 43 in such manner as to limit its effective area to the portion within corrugation 38 is a rigid annulus 32 the outer edge of" whichisreceived within an annular recess 36 formed in:the bottom face of middle section HZ), such annulus 39 being clamped in place between lower diaphragm l3 and middle section Hb.

Middle section H2) is machined on its top and bottom" faces and provided. with screw holes extending therethrough registering with the holes in upper diaphragm i2 and a like series of holes in lower diaphragm I3.

Underlying upper diaphragm l2 and overlying reinforcing disc 3'! on lower diaphragm i3 is a button or spacer it, the same taking the form of a cylinder having a round or frusto-conical top surface in proximity to the bottom side of upper diaphragm l2. Spacer 4! is characterized by the presence of a central opening 22 and a'narrowslot' 43 milled or cut in the side wall thereof. Intoslot 4-3 projects one end of a flexible strap or springe which has been partly but not completely punched through, as by the introduction of a suitable tool through opening 32, to hold spacer 4i firmly in position on spring d4. The opposite end of spring 44 extends between two opposed pairs of lugs or pins 45 which are peened over tohold spring l'in place, such pins 55 being formed on the bottom of an inwardly'projecting portion 46 that extends from and is formed. integrally with the annular body portion of middle section Hb. Spacer. M is' of a height such as to substantially equal the. distance between the bottom face of upper diaphragm l2 and exposed top face of disc 31 when the two diaphragms are in their normal or unflexed positions.

Inwardly projecting portion 46 is characterized by an inclined bore 3?, threaded at its anterior end, which bore is accessible from the exterior of middle section lib. A gasket 43 and a closure screw fi'il threaded to fit the threaded or anterior portion of inclined bore 4! permit access to bore 47. Extending from. chamber !5 into inwardly projecting portion 26 and into the pos terior end of inclined bore 3-? is an adjustingsorew 58, the same being mounted for movement axially of. inclined bore 4?. Adjusting screw is provided with a slot at its end by ns f which.

when closure screw 49 and gasket d8 are removed,

screw 52* can be adjusted lengthwise of bore 31 from the exterior of middle section lib.

The head of adjusting screw 5% bears against or is in proximity to spring id and c'on'stitutes'a fulcrum about which spring M can bend under the influence of force applied to'spacer ll from the bottom face of lower diaphragm 53. By moving the head of adjusting screw 58 closer to spacer ll, increased resistance is offered to bending of spring 24; similarly, by retracting adjusting screwv 56 within inclined bore it, decreased resistance is offered to bending of spring 35. Whether spacer A! will or will not operate to transmit to upper diaphragm 12 a force applied to the bottom face of lower diaphragm i3 depends in part on the value of the force and in part on the position of adjusting screw 59, which, in general, should be so positioned as to permit the transmittal only of forces of substantial magnitude. 7

Bottom section 1 lo, which, as shown in Figure 3, is provided with a series of screw holes registering with those in theparts previously described;

includes a machined mounting flange 54 and a shelf-like portion or plate 55 underlying and to some extent backing, but not in ordinary circumstances in contact with, the bottom face of lower diaphragm I 3. Bottom section He is characterized, among other things, by 2. depending skirtlike portion 56 for entrapping air, such skirt-like portion defining the lateral limits of space I6 except toward the left-hand side of bottom section I I as represented in Figures 2 and 3, where a semi-circular extension 51 of skirt-like portion 55 reaches almost to the outer periphery of bottom section I30. Semi-circular extension is of the same height and thickness as skirt-like portion 55 and, where it adjoins the main body of skirt-like portion 56, is open to permit the free passage of air into and out of semi-circular extension 57.

Extending upward through plate 55 from a point within semi-circular extension 51 of skirtlike portion 56 is a passageway 58 through which trapped air may escape from space I6 in bottom section I Io into chamber I5 between diaphragms I2 and I3. ,To the same end, lower diaphragm I3 has therein a hole 59 which registers with the upper end of passageway 58. Also, the machined bottom face of middle section lib is provided with a shallow recess 50 which permits air escaping from space I5 by means of passageway 58 to by-pass metal annulus 39. Thus chamber I5 in middle section III) is in constant communication with and, as regards pressure, under the same conditions as space It in bottom portion IIc.

Plate 55 is also characterized, at least in the preferred embodiment of the invention, by a depending internally-threaded boss 8! which is formed integrally with and inwardly of an inwardly projecting portion 62, the latter being itself integral with skirt-like portion 55 and plate 55. Boss 6| receives a short connecting pipe 53 fitted at its other end into the upwardly extending side connection of T I. Immediately above boss BI is a shallow chamber 64 formed as a depression in the upper face of plate 55, such chamber 64 underlying lower diaphragm I3. Bilge water under pump pressure that makes its way from T I through connecting pipe 63 exerts a force that is felt in chamber 64, where it imposes a force upon the bottom face of lower diaphragm I3 but more effectively against the movable portion defined by corrugation 38.

As shown in Figure 2, bottom section He is provided with a communicating passage 65 extending downward from chamber 64, such pas-' sage terminating in an opening 63, threaded at itsouter end, which is formed within the limits of inwardly projecting portion 62. opening 66 is shown as closed by a screw-threaded plug 61, this being the normal state of affairs when pump control unit 8 is mounted directly above the side connection T I as shown in Figure 1. If, however, T I is so positioned that the side connection and straight-through connections lie in a common horizontal plane, connecting pipe 63 will enter the housing through threaded opening 66 in inwardly projecting portion 52, thereby communicating the pressure of the liquid in the pump discharge outlet 4 through opening 66 and passageway 65 to chamber 54. In such case, plug 61 is used to close the opening in the bottom of threaded boss BI.

This alternative method of mounting has an advantage over that illustrated in Figure 1 in that pump control unit 8 is brought closer to the bottom of hull I of the vessel, advancing Threaded 6 thereby the operational threshold or point at which pump 2 begins to function.

For marine purposes, the major metal components of pump control unit 8 will ordinarily be of bronze, brass or the like, although other corrosion-resistant materials may, if desired, be employed in lieu thereof. The diaphragms and other non-rigid parts; e. g., gaskets 30 and 48 and breather tube 21, may be of natural rubber, synthetic rubber, synthetic resin, or any other composition that will serve the intended purposes. Reinforcing elements such as discs 35 and 3'! may be of corrosion-resistant metal, hard rubber or synthetic resin, as may be preferred. Inasmuch as switch 24 is located in space I4 in top section Il a, which space is open to the atmosphere, switch 24 may be of conventional micro-switch construction preferably having a travel for actuation of but a few thousandths of an inch and requiring very little movement of the diaphragm I2 for its actuation and therefore little breathing through the tube 21. Consequently the atmosphere in chamber I4 tends to remain dry and pure through many different seasonal and atmospheric changes.

The electrical components of the system may be connected in any manner that will provide the desired results, one method being illustrated in the wiring diagram shown in Figure 4. In the circuit therein disclosed, a single pole, doublethrow switch 69 is interposed between pump control unit 8 and battery I0. In one position of switch 55, shown in solid lines, pump control unit 8 is in effect by-passed, thus permitting pump 2 to be operated as if pump control unit 8 were not present for such time as the circuit is kept closed. In the other position of switch 69, indicated in dotted lines, pump control unit 8 intervenes between pump 2 and battery I8, thereby imposing upon pump 2 and the system as a whole the various conditions of actuation and deactuation which pump control unit 8 is designed to initiate, continue or discontinue, as the case may be.

In operation, the level of the bilge water colleeting in hull I of the vessel rises as the quantity increases, sealing ofi from the atmosphere inlets 3 at the base of pump 2. When the level of liquid reaches the lower extreme of skirt-like portion 55 of bottom section He, the air present in space I6 becomes trapped therein. As the level continues to rise, air in space I6, passageway 58 and chamber I5 is placed under superatmospheric pressure. Such pressure is exerted equally in all directions against the walls or limits of chamber I5 but is without substantial effect on lower diaphragm I3 for the reason that it tends only to force lower diaphragm I3 downward into contact with shelf-like plate 55. However, the pressure of the air on the lower face of upper diaphragm I2 causes the same to flex at corrugation 36 and to move upwardly into contact with or to induce upward switch closing movement of the switch button 25 of microswitch 24, causing the switch 24 to close the circuit to the pump 2.

This is the operational threshold, for until this condition is reached the pump 2 is idle unless cut in manually by movement of switch 69 to the solid line position shown in Figure 4.

Once the operational threshold has been reached and pump 2 has been actuated, liquid under pressure is discharged in a stream through pump discharge outlet 4. For the most part, such liquid passes through discharge line 5 into dis charge port fitting 6 and out of the vessel, but

part of it enters connecting pipe 63. Assuming the presence of some air in connecting pipe 63 and chamber 64 underlying lower diaphragm l3, fluid under pressure entering connecting pipe 63 transmits its pressure to the under side of lower diaphragm [3; this pressure being substantially commensurate with the head between the chamber 64 and the outlet 6 plus the line loss between the T 7 and the outlet 6. Since usual sump or marine installations may put the outlet from about one foot to ten or fifteen feet above the diaphragm l3, the head in the chamber 64 when the pump is discharging will run somewhat greater than the difference in level between the diaphragm and the outlet depending on the character of the outlet pipe 5. In all events this head is built up and the corresponding fluid pressure in the chamber 64 developed 'as soon as the pump begins to discharge and fills the pipe 5.

The efiect of this pressure in the chamber 64 is to fiex lower diaphragm l3 and cause spacer M to move upwardly against the resistance of the spring M as the same may be adjustably influenced by the screw toward or into contact with the lower face of the upper diaphragm i2. Assuming that the outlet 6 is at such an elevation that the head of liquid in the pipe 5 that is reflected in the chamber 64 has a greater influence moving the diaphragm I2 and spacer 4| upwardly than the resistance of the spring 24 to such movement, then the spacer will contact the diaphragm l2 and augment the pressure of the diaphragm 12 upon the switch button or pin 25 and will tend to hold the switch closed while the pressure in the chamber 15 diminishes as the level of bilge water falls.

Assuming also that the head of liquid in the discharge line is such as to overcome the resistance of the spring 44 by an amount measurably greater than the net influence of the static pressure of the bilge water in the chamber l5 that initially closed the switch 24, then as the pump 2 removes bilge Water from the hold I and the level of liquid falls with respect to the diaphragm l2 and exposes the lower edge of the skirt-like portion 56, returning the chamber Hi to atmospheric pressure, the tendency of the diaphragm l2 to permit the switch 24 to open will be more than offset by the tendency of the diaphragm [3 to retain the switch in closed position so that the pump is induced to continue in operation to lower the liquid level below the control element and continue to discharge liquid from the bilge so long as the pump can draw in liquid through the inlets .3. When, however, the bilge is substantially dry and the pump draws or begins to draw air through its inlet 3 thereby tending to lose or reduce its discharge pressure so will the pressure under the diaphragm l3 be diminished to permit the spring 4d to move the diaphragm l3 and spacer ii downwardly to open the switch 24 and stop the pump. Thereupon whatever liquid lay in the discharge line may drain back through the pump into the bilge without building a pressure under the diaphragm l3 sufficient to reclose the switch if the spring 44 is adjusted properly with respect to the height of the outlet 6 for this purpose.

. On the other hand if the spring '44 be adjusted, as could be desirable .in some cases, to restrain the diaphragm l3 from upward movement when the pump is discharging then the control would beresponsive only tothe pressure in the chamber l5, i. e. to the level of bilge water, which how-1 ever would tend to turn the pump on and off with a narrow range depending on the travel of the switch button and the sensitivity of the diaphragm 12. Since we prefer that this travel be small and the diaphragm be freely flexible to enhance our preferred mode of operation and method of control we prefer to so adjust the spring 44 to take advantage of the coaction of both diaphragms for the purposes above described.

However, if the pressure exerted by the spring M downwardly upon the diaphragm I3 is substantially eliminated and the level of the outlet 6 is much higher than the level of the diaphragm, for example ten feet higher, when the diaphragms are sensitive to only a few inches change in liquid level, then the pumping cycle will be initiated as above described and the level of bilge water reduced down to the ports 3 and the pressure in the diaphragm chamber 64 reduced when the pump loses its full discharge pressure thereby tending to open the switch 24. Here, however, in the absence of any effect from the spring 44 the head of water in the discharge pipe 5 in its back flow to the pump may well be sufiicient to raise the diaphragm l3 and reactuate the pump motor with the not very happy or desirable result in most instances or continuing an on and off operation of the pump more or less indefinitely or until by successive surges a'substantial quantity of the water of the discharge pipe may be ejected from the outlet 6 to reduce the effective head at the end of a cycle. In this illustration it will be apparent that we have not fully considered the purpose and effect of the difference between the effective areas of the portion of the diaphragm I3 which is responsive to the pressure in the chamber 64 and the portion of the diaphragm l2 that is responsive to pressure in the chamber l5. This diiference in area works on the side of the function of the spring 44 in avoiding the awkwardness above described and relieves the spring of a por-' tion of the burden it would otherwise have to assume were the effective area of the diaphragm 13 on the side of the chamber 64 as large or larger than the effective area of the diaphragm l2.

Thus in the preferred form of our invention we bring into play advantageously the reduced effective area of the diaphragm [3 in its response to pressure in the chamber 64 and the adjustment of the spring M, it being practicable under these circumstances to use a relatively light small spring which is flexed through a small displacement and is readily adjustable through the screw 58 to cover a wide'range of conditions of operation and give the desired preferred method and mode 'of operation to the action of our control under widely different conditions of use. That is to say, when the outlet 6 is only a foot or two above the diaphragm I3, the spring 44 may be so adjusted as to exert little or substantially no downward pressure on the diaphragm l3 whenthe diaphragm has been raised by the discharge head to contact with the raised diaphragm l2. The same control mechanism, however, when installed with the outlet '5 fifteen feet higher than the diaphragm l3 may, by adjustment of the screw 58 to increase the pressure of the spring upon the diaphragm, substantially balance or compensate for the increased head of the .discharge line to guarantee that when the bilge has been pumped down to the level of the inlets 3 that the switch 24 will be opened and will not be reclosed by the head of water in the discharge pipe after the pump has .once been stopped. We

are aware, of course, that at least theoretically a check valve in the discharge line beyond the T 1 on the side of the discharge port 6 would tend to relieve certain aspects of the problems we have mentioned but such a valve would be directly subjected to all the destructive forces of corrosion and jamming and impairment by the passage of anything but pure liquids therethrough that are ordinarily found in bilges or suinps whereas our control mechanism is essentially and primarily protected from the deleterious effects of the fluid it controls and eliminates the need for a check valve besides.

In the preferred form of our invention the pump discharge outlet is preferably but a nominal height above the inlet port 3 such that when the T connection is placed horizontally and the control device is connected through the port otherwise closed by the plug 61 that the lower edge of the skirt 5'! will be so close to the bottom of the bilge or sump that the switch 24 will be closed when the level of the bilge water is only about 1 deep. When the control element is connected as shown in Figures 1, 2 and 4 with the T 1 upright and when the conduit 63 comprises a short nipple the elevation of the skirt 51 will be such as to start the pump when the level of bilge water is approximately 4 high. If a higher level of bilge water is desired to establish the turnon point for the pump the length of the conduit or nipple 63 may be correspondingly increased. Influencing the. turn on point are such factors as the area of upper diaphragm [2, the switch pressure, and the fluid being controlled. In a preferred form of our invention, the intake ports 3 may be conveniently formed so that a shut-off point as determined by the level of water and bilge when air is first inducted into the pump may be approximately as little as Thus our control and the mounting thereof in relation to the bottom of the sump or bilge and in relation to the discharge line and with the facility of adjustment afforded through the screw 50 and spring 44 facilitates a wide and selectively variable range of operations and installations and a wide choice of levels and cycles for such purposes as may be desired.

While the foregoing description is directed to a preferred embodiment of the invention, it is not necessary that the parts, arrangement of parts or mode of operation appurtenant to such embodiment be followed in every case. For example, upper and lower diaphragms l2 and I3 may be used with or replaced by bellows, pistons and other pressure-sensitive elements; similarly, the micro-switch may be replaced by a snap switch, a magnetic switch or any other type of switch. Nor is it necessary that the control unit embodying the switch be located in juxtaposition to the pump: it may, if desired, be located at a point remote therefrom. Neither is it necessary that the control unit, even though designed for and especially valuable when used in conjunction with a bilge or sump pump, be employed with a bilge pump, with a sump pump or even with liquid-handling pumps generally.

Specific changes that may be made include the omission of corrugations 36 and 38 on diaphragms l2 and I3, respectively, this inasmuch as the required movement can be obtained with flat diaphragms made of flexible material, especially if reinforcing discs 35 and 3'! are not glued thereto over their entire areas but are so fastened, as at their centers, to permit them to rise as the diaphragms assume or approach spherical shape. Other changes go to the height and shape of spacer 4|, which, in order to allow more movement of the spring before holding the switch in the on position, may be less than the distance between the bottom face of upper diaphragm I2 and the exposed top face of the disc 31; its rounded upper end may conveniently take the form of a spherical segment the surface of which is generated from the center of the spring slot, this having the advantage of providing a fairly constant eifective length as spring 44 is deflected. In some instances, lower diaphrgam I3 may be eliminated; in others, the air trap therebelow may be omitted.

While we have illustrated the preferred form of our invention with respect to the actuation of the electrical switch 24, we do not necessarily cuit or instrumentality, it being within the province and utility of our invention that the button 25 actuate a pneumatic, hydraulic or other instrumentality or relay for purposes analogous to those accomplished electrically through the switch 24. For example, a servo-motor or like mechanism operating a fluid-pressure motor may be employed to the same end. In such circumstances, the pump may, if desired, be air-driven, steam-driven or engine-driven rather than electrically driven, as in the embodiment of the invention shown in the drawings. In any event, modifications in the unit and in the system, either by way of simplification or elaboration, may readily be made without departing from the spirit of the invention.

It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty reside in the invention.

What is claimed is:

1. In a pumping system, a pump, a discharge line from said pump, means for actuating said pump and a control device for controlling said actuating means, said control device having one means responsive to water level for initiating the actuation of said pump and having a second means independently responsive to pressure in said discharge line for maintaining the operation of said pump after the water level has changed from the point of initiation, said second means being responsive to a reduction of pressure in the discharge line to terminate the actuation of said pump.

2. A pump control comprising a plurality of pressure-sensitive members responsive to different conditions to actiate means to operate a pump, one of said pressure-sensitive members being responsive to changes in liquid level and the other to the presence of liquid under pressure in the system independently of said liquid level, said other member acting through said one member to control the pump.

3. A pump control as in claim 2 in which, in actuating said means to operate the pump, the pressure-sensitive member responsive to the presence of liquid under pressure supersedes the action of the other pressure-sensitive member.

4. The pump control as in claim 2 in which said pump operating means comprises a single switch responsive to both said pressure sensitive members.

5. The pump control as in claim 4 in which the switch overlies the first named pressure sensitive member, the first named pressure sensitive member overlies the second named pressure asserts in'isai'd housing, a switchactuatablebyjmov'eijnient of said diaphragm means, said housing having a fluid tight depending skirt-like portion penat its bottom to risi'ng'liquid and otherwise Ic'losed except for communication with said chamber, a second chamber communicating with pum discharge pressure, and second flexible dia-' 'f phragm meajns closing saidsec'ond chamber and ppei'ativ'ely connected to actuate said switch independently'ofthe tendency of sai'd'first diaphragm means to actuate said switch. III "7. The control of claim 6 with means for momfying the'relative responses of said diaphragm means to pressures in said first and second chambers.

8. The control of claim 6 withaidjust'able re- "silient means opposing the flexing of said'second flamed diaphragm means. I I 9. The control or claim 6'in which said dia- Iphragm means are coaxially disposed in said housing and of different efiective areas, and means fortransmitting movement of said second diaphragmmeans to said switch through said first-diaphragm means.

10.'A pump controlin'dependently responsive d m m "sa hous i zals o skirt-like portion open I at its bottom to means, a fluid tight conduit leading fro Il f d i i "ahdTto in ana i fcomprising a'housing having a chamb in said chamber flexible 'di'aphra in means being actuatablebymovement of said; diaphi means; a second chamb'er'definedinjpart liquid and otherwise closed I except for cation with said second chamber, a thiric'haih- 'ber Communicating {with pump 'disch arge pres:- sure, flexible diaphragm means closing' saidthird chamber. and operatively connected toactuate said switch independently of said first diaphragm 7 Q 3 sealed to sai d first chamber-and 'co'nnecti'ng t he same to atmospheregand electrical leads from "said switch' for actuating said pump *carrid 'in said conduit. I W I I I,

H O D HERBERT W. KAATZ.

References Cited in the fileof this patent UNITED STATES PA'IENTS Number Name Date 1,253,687 Hicks Jan. 15,1918 1,380,442 Trumble June 7,-1921 1,744,684 Grifiith Jan.; 21,:1930 1,760,382 Teesdal'e May 27, $1930 1,913,557 Millar June 13,119,333 1,952,265 Leland Mar.j 27,-;1934 2,488,506 Bernhardt ;;;N0v.'15,"1949

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