US3002064A - Sump pump and flood control equipment - Google Patents

Description

Se t. 26, 1961 A. L. NIELSEN 3,002,064

' SUMP PUMP AND FLOOD CONTROL EQUIPMENT Filed March 26, 1958 2 Sheets-Sheet 1 FIG I- IN VEN TOR.

I AXEL L- NIELS ATTORNEYS Sept. 26, 1961 A. NIELSEN SUMP PUMP AND FLOOD CONTROL EQUIPMENT 2 SheetsSheet 2 Filed March 26, 1958 F ICE--2- z aii INVENTOR.

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ACTTORN EYS tf d States PfltentO Filed Mar. 26, 1958, Ser. No. 124,193 14 Claims. c1. 200- -83) The present invention relates to improvements in electrically operated sump or flood control pumps, for either rural or urban installation and more particularly to novel and improved provisions whereby the commencement and termination of the operation of the pump are rapidly and reliably controlled under all possible operating conditions to be encountered. The invention provides a pump control whose operation is based on the response of a special multiple diaphragm unit to three pressure conditions, i.e., to the hydrostatic head in starting, to the pump pressure at its discharge 'duct and to the operating vacuum at its intake.

This application is a continuation-in-part of my cc- ,pending applications Serial No. 684,111 and Serial No.

684,308, both filed September 16, 1957, of which the former is now Letters Patent No. 2,922,854 of January 26, 1960.

It is a general object of the invention to provide a control for the operating motor of either a pump impeller installed in a sump or one fitted in a sewer riser as an anti-flood precaution, In either case the control embodies a switch and a multiple-diaphragm, pressure responsive unit to govern the making and breaking of a motor circuit at the switch in response to the three pressure factors mentioned above, or a combination of them.

In accordance with another object, pressure and vacuumchambers defined by the multiple diaphragm unit of the control are respectively in static pressure communication with the pump adjacent its hydraulic intake, at

its discharge and at its impeller eye.

' This enables the control to most rapidly and efiiciently respond to all sump or sewer flooding conditions. Static pressure of course controls the initial closing of the motor switch and starting of the pump. If operating under a high head, it is desirable to use the'pump discharge pres- 'in the sump.

' 2 ing the'spacing of the motor switch from the diaphragm unit which controls its closing and opening.

Another specific object of the invention, particularly in an embodiment of its principles as applied to a sump pump, is a control unit of very simple compact and inexpensive sort which may be supplied as a part of an original sump pump assembly or may optionally be supa plied as an adapter type motor control easily and quickly applied to an existing sump pump to afford perfect control of its motor. In either sort of installation the unit has the important advantage that, although it is hydraulically connected to the pump, it need not be physically supported by the pump; nor need it be submerged A further specific object, pertaining to both embodiments of the control illustrated herein, is to provide a motor control unit including a diaphragm-operated motor control switch wired to a primary electrical connector which plugs into a suitable electric outlet, as well as a further electrical socket connected in series with such connector and switch, into which the usual plug connector of an existing sump pump motor may be plugged in the event the control is furnished as an adapter.

In an adaptation of the principles to the flood control of buildings in the event of overloading of a municipal or other sewer system, or its equivalent, the improved control is structurally very compact, simple, inexpensive sure to keep the switch closed and insure continued pumping.

On the other hand, in low head operation intake suction operation of the diaphragm unit better performs this function as vacuum at the impeller intake eye increases. Either condition may be the major factor in the operation of the diaphragm, and both may be in effect at the same time, once the pump is started.

'In respect to the vacuum control aspect of the invention, it is an object to improve the eifect of the vacuum for its intended purposes, in a multiple diaphragm installation as described. This is accomplished by providing improved means for pressure-interconnecting the vacuum control chamber of the unit, defined by a pair of opposed di'aphragms, with another chamber'of the unit, also in part defined by a diaphragm. The result is that the eiiect of the vacuum in the first named chamber to move one of the diaphragms thereof in a given direction is overcome or overbalanced by the eifect of the equal vacuum in the other chamber of moving its diaphragm in the opposite direction. This intensifies the vacuum-responsivity of the multiple diaphragm unit as a whole.

A further object is to provide a control W-hichis freed from reliance on a float or other mechanical switch operating device as the result of its actuation, as above described, solely in response to various pressure conditions imposed on its multiplediaphragm unit.

In accordance with' a still further and more specific object of the invention, the control of cut-in and cut-out of the pump motor may be governed by ad-justably vary-' and readily installed in or removed from a drain and,

clean-out riserby an-unskilled person. As installed in a rural building or other setting not associated with a,

sewer system, the apparatus of the invention also elim;-

inates the need fora relatively large sump and sumpv pump, and the expense, danger and odor incident to their use. Its units may be installed in a sub-floor collector riser constituted by a four inch pipe;

It is a general object of the invention, as so embodied, to provide an improved floor control assembly featuring aself-contained and self-priming double pump unit including an above-floor pump adapted to be fitted to a basement floor clean-out opening of a plumbing system, preferably in association with an improved one-way back water control plug (as illustrated and described in my above identified application, Serial No. 684,308) posi-,

tioned inthe riser beneath the entrance. of the usual storm drain line to the riser and trap. The pump is direct-driven by a motor positioned directly thereabove, under the control of the multiple diaphragm unit referred to, having its intake side in downward communication with the housing of a further primer pump disposed in the riser; and the diaphragm unit may be directly mount;- ed on the above-floor structure, or otherwise. The abovefloor pump is quickly primed by the sub-floor priming.

pump, eliminating an operational difiiculty characteristic of existing generally comparable installations, which require that connecting hose be full before satisfactory operation is possible. I

As distinguished from all other so-called self-priming pumps, it is not necessary to make any provision whatsoever in my improved pump to hold water or other liquid captive to a predetermined level at the intake side of the pump in order to prime it. I

The foregoing as well as other objects will become more apparent as this description proceeds, especially when considered in connection with the accompanying. drawings illustrating preferred embodiments of the invention, wherein:

FIG. 1 is a fragmentary view, partially broken .away

and in vertical section through a control unit or device in accordance with one embodiment of the invention in,

a sump pump;

FIG. 2 is a fragmentary view, in vertical axial section and partially broken away, of a pump unit and control of amassecommunicating certain chambers of the control unit for improved vacuum responsivity.

Referring first to an adaptation ofjhe principles of the invention to a sump pump installation, generally designated 10, asillustrated in FIG. 1 of the drawings, a portion of. a vertical motor shaft housing 11' is shown, with. a motor driven shaft 12 projecting downwardly therein. Shaft lZ is securedto a centrifugal pump im- [9161161113 in an impeller housing 14 beneath the shaft housing. A conventional intake trap 15 is associated beneaththe pump impeller housing 14 and the latteris pro.- yided with an upright discharge pipev or duct 17.

A diaphragm and switch housing or casing is generally designated 16, being constituted by four casing members 18', 19, 20 and 21 suitably secured together in coaxial relation. A primary flexible diaphragm 22 of suitable flexible material such as spring brass, treated fabric, or the like, is marginally clamped between members .18 and 19 to in part define a static pressurechamber 23 of small volume on its left and a vacuum chamber 24 onitsright.

A suitable clamp member 25 is provided on, the casing member 18, by which the control housing or casing 16" maybe supported at a desiredeletvation on the. pump discharge pipe 17.

The casing member 20 is inthe form of anannular ring mounting a dual diaphragm unit. 26 betweenthe casing members 19, 20 on either side thereof. This diaphragm unit comprises a first or inner flexiblediaphragm 27 and a second or outer simi ar diaphragm 28,, both .Of material similar to that of the primary diaphragm 22. They are marginally clamped between the casing ring 20 and the respective casingmembers 19, 21, so as to enact with thering in defining an air space or air p essure chamber 29 therebetween. Diaphragms 27, 28 are, further maintained in fixedly spaced relation to one anotherby a short spacer sleeve dtlattheir centen this part being clamped in place by an axial stud 31. "lThe -free end of stud 31 extends through an axial aperture 32. of substantial' size in the adjacent face of casingmemher 19, for engagement by a contact disk-33 on primary diaphragm 22 a The inner peripheral wall 34 of thediapbragm spacing ring 20 is of outwardly tapered or frusto-conical outline, and it is seen that there is thus provided an. air pressure. chamber 29 in which the area, i'.e., of, eifective, pressureresponsive flexibility, of the outer diaphragm 21.8 exposed to pressure is largerthan the area of the inner diaphragm. 27 similarly exposed.

Structural featuresof the dual diaphragm unit 26 are similar to what is illustrated and described inmy Letters Patent 2,730,591 of January 10, 1956, and it canbe seen that when pressure exists within the chamber 29. thereis a resultant force to the right, as viewed in FIG. 1, tending to move the diaphragm unit in that direction, due to the force times area differential product. Itis. also seen that in using a pair of opposed diaphragms of different area it is possible to employ relatively large diaphragms, with resultant freedom of movement, and, avoidance I oifatigue and the like. The actual difference in area between the diaphragms 27, 28 may be as little. as required.

The small volume static pressure chamber 2,3.is downwardly communicated by. a passage 36 with ahydrostatic pressure tube 37 of relatiyely large internalbom size, which tube terminates at a level adjacent but somewhat above the pump housing 14. This insures that the. tube 37 will empty gravitationally after each pumping cycle, and not tend to buildup a head therein after repeated frequent cycles, such as might affect thereliability of the control operation.

The vacuum chamber casing member 19 is bell-like in outline. and the inner diaphragm27 of thezdual. dia-' phragm unit 26 coacts with it in defining the chamber 24, which it will be noted is of relatively large volumetric capacity as compared with vacuum chamber 23.

A vacuum line or tube 39 of small internal bore size, as compared with tube 37, extends downwardly from the chamber 24, being brought laterally at 46 into ccmmunication with the intake-side of the impeller housing 14. The lateral tubelength. lit-extends into the trap 15 and is provided with an upturned end 41 coaxial with the intake eye, of; the impeller housing.

Theair pressure chamber. 29 between diaphragms. 27, 28 is. connected by a. tube or pipe. 43 with the upright pump discharge, pipe. or conduit, at. a point 4 1 substan: tially below. the connection at. 4-5 of the tube 43 to the control housingcr casing 16. Thus, entry of discharge liquid into the. chamber 29, under the substantial pressure of pump discharge, is prevented.

An appropriatev electricalv control switch 47 is mounted within. the space 48 between. diaphragm 28 and the final. cesiugmcmber 21, which space is at atmospheric pressure. Switch 47 is a suitably enclosed, normally open type having. a controlnbutton. 49 positioned directly to the right of the center. of the diaphragm 28, for actuation by thev clamp stud 31 for the latter. The button may be springv urgedor the; switch may. be a reversible snap acting one, but, in accordance with the invention; switch. 47 is: one. which Will be actuated to close. an electrical circuitonly when a; substantial force of, say 2 0 oz.,.-is exerted on. control buttonv 49. Likewise, the switch. 47' is chosen so that whenthis force drops to, say, 302., the switch will return to. itsnormally open condition;

Switch 4 7 .isappropriately secured to a suitable-U- shaped mounting bracket-51, to which a. tubular horizontal mounting fitting 52. ,coaxially ahgned. with the. switch control button 49 is in turn secured. The tube fitting 52 is..threaded.- extem-ally for, rotative adjustmentin a lateral hoss53ofcasing. member 21, and a nut 54 is. applied to it tohold. thefitting and switch rigidly in place when adjusted as desired.

Conventional. wiring leads 5.6; are applied to the switch terminals andarebroughtoutwardly of casing 16. through tubular. fitting 52. The latter may be open. at its outer end, to maintain.v atmospheric-pressure in casing chamber 4%, or an. atmospheric pressure port 52 may be formed-v intlie casing, member. 21.

Thus it is seenthat regulation of the control action,

maybe. accomplished by a .rotativeadjustment of the fittin-g52 in casing boss 53, enabling the switch button 49 to. be. positioned variably in relation to. diaphragm 218 andthus to. regulate the commencement and duration of motor cycles.

In the sump pump unitillustrated. in FIG. 1. the elcctrical. leads 56 from theswitch. arev brought out through thetubularmounting fitting; 52,. preferably inv the. form of a conventional. insulated cable 58 leading to. a conventional electricalplug-in connector. 59, and a type of female electrical socket member 6t? is connected-in the. cableflSS with. its socket. terminals 61 wired in series with the plug 59 andthe terminals of switch 4-7. Cable 58 may be. of any desired length, so that in applyingthe control. unit as a replacement, all that is necessary to do is toconnectitheexistingelectrical. motor connector (not shown.) of. the sump pump. in the sockets 61, then plug.

the connector 59 suitable electricalv outlet socket or box. It is then not necesary to make any particular mounting for the control casing or housing 16, and any support on which it may be suspended will suifice.

Inithe operation of the structure thus far described. it is evident that as the level of liquid rises predeterminedlyin the respective hydrostatic pressure and vacuum lines 37, 39, the respective static pressureand vacuum chambers 23, 24 will be increasingly pressurized, although sponsor. a

39 being of small bore, compresses air in the large vacuum tube 39 being subject as pumping goes on to the suction at the intake of the impeller.

The resultant partial vacuum becomes effective through vacuum tube 39 on chamber 24, and this vacuum causes the diaphragm structure to be held in closing relation to the switch 47. The vacuum is not reduced sufiiciently to enable the di-ahpragm to move away from the switch button and permit the switch to open until the level has dropped beneath the intake, or impeller eye, end 41 of the vacuum line 39. When this occurs, the vacuum in chamber '24 is immediately broken, and switch 47 'will open.

The provision of the vacuum line 39 is seen to constitute one of two available simple and convenient ways to materially lengthen the operating cycle of the motor, once it has been started, and thus practically dry out the sump before the motor cycle terminates.

The other control aspect of the improvement, present in both of the embodiments of the invention herein described, is in the holding of switch 47 closed by internal pressurization of the dual diaphragm unit 26, through tube 43, under the discharge pressure in pipe 17 as applied to the differential in area between the constituent diaphragms 27, 28 of that unit. As indicated above, this action is most effective when the installation is operating against a high hydraulic head, the discharge pressure differential being ampleto keep switch 47 closed. The other or vacuum effect is better effective against a low head. In both instances initial starting is accomplished by hydrostatic pressure in tube or line 37, and the two effects in many instances take place concurrently.

Reference should now be made to FIG. 2 of the drawings, showing an alternative embodiment of the invention in an anti-flood sewer control installation. Inasmuch as the control provisions in this modification closely re semble, if not being identical to those of FIG. 1, corresponding reference numerals are employed to designate corresponding parts or relationship, and repeated descrip tion is dispensed with. The reference numeral 64 generally designates an improved self-priming pump unit as installed in an upright sewer riser or standpipe 65, for example, as in a typical domestic installation. The usual storm drain or seepage line (not shown) opens to this riser somewhat above its trap (not shown) which discharges to the city sewer.

The usual sanitary system of the installation, from tubs, sinks, toilets and the like, discharges to the sewer downstream of the trap. 7

On many occasions it is desirable to control and confine the rise of sewer liquid in riser 65 beneath such seepage line, as by the use of an expansible backwater contnol plug such as is illustrated and described in my the boss 69 surrounding the intake eye 71 to a centrifugal impeller 72 in this housing. Impeller 72 has its hub 73 fixed on an'elongated driveshaft 75 extending downward- 'ly and coaxially through the primer housing 66. The

latter may be of, say, 3 /2 inch maximum diameter for installation in a four inch pipe riser.

Pump housing 70 discharges laterally through a discharge pipe 77 to which the upright air pressure tube or line 43 of the control casing 16 is connected; and pipe 77 may be return-connected to the sanitary line, or

it may be connected to discharge to the exterior of the dwelling or other building in question.

A centrifugal priming impeller 78 featuring a top shroud disk or plate 79 is secured to the shaft 75 adjacent the lower end thereof, within a downwardly tapered conical bottom portion 80 of primer housing '66. This end of the shaft may be appropriately journaled in a fixed intake trap 81 secured beneath housing 66, through which liquid enters to the blading of impeller 78 from the storm drain line therebencath.

The upward divergence of the tapered lower housing portion 80 and the top shrouding of impeller 78 at 79 considerably assist the latter in obtaining a rapid initial lift of water, which is then further speeded to housing 70 by the upward convergence of the housing 66 above impeller 78.

It is the function of the impeller 78 to positively and rapidly prime the above-floor pump housing 70 through tubular connector 67, whenever any water collects in the riser, whether storm drainage or otherwise. In this the priming pump housing 66 serves the combined functions of an impeller housing and an accelerative discharge pipe to the housing 70.

- A suitable axially acting, spring urged rotary seal 83 is interposed between the upper end of the discharge impeller hub 73 and a hollow top extension 84 of centrifugal pump housing 70, the seal preferably including a carbon seal disk 85 to contain upward flow at this point.

Drive shaft 75 is appropriately journaled by a ball bearing 86 in a cylindrical mounting block 87 upwardly of pump housing 70, and the upper end of shaft 75 is connected by an appropriate coupling 87' with the depending shaft 88 of an electric drivemotor 89 for control by the switch 47. The switch is similar in all particulars to that of the first embodiment, hence requires no further description. Its electrical conduit 58 will not incorporate the optional socket '60 of FIG. 1.

The shaft sealing, bearing and coupling provisions just described are encased in a tubular motor mounting sheath? 90, which is clamped about a motor boss 91 at its top and about the axial housing extension 84 at its bottom,

a clamp for this purpose being designated 92.

The operation of the system of FIG. 2 is, in regard to the multiple diaphragm operation of switch 47, identical with that of the sump pump installation of 'FIG. 1, save for the fact that the hydrostatic and vacuum tubes 37, 39 are brought down to the priming impeller 78 rather than main pump impeller 72. However, in the broad sense of the invention the two types of tube connection are equivalents.

The improvement of FIG. 2 provides an entirely selfcontained, self-priming flood control assembly of great compactness, rapidly and easily mounted in operative position by an entirely unskilled user. In a rural or similar non-sewer installation the danger, cost and annoyance of a sump system may be avoided by the system of FIG. 2.

Priming impeller 78 lifts water practically instantaneously to impeller 72, upon static pressurization of tube 37, to close switch 47. Thereafter, either the pressurization of the internal space 29 of the dual diaphragm unit 26from discharge line 77, or the evacuation of vacuum chamber 24 through tube 39, or both, serve to keep the switch closed until the desired result is had, regardless of the hydraulic head which is involved. I It is to be emphasized that the essential purposes of the' meanes- 7 primin'g'impeller 78 and its'shaped housing 66, delivering through a-coaxial tube or conduit e'i'to'the intake of the main impeller 72, is to efiect a rapid lift of the liquid't'o the'main pump, which is, the essentially efficient agency for pumping. A rapid lift in a comparatively high intervening housing section of tubular form is made possible, to a pump whose-primary function is to produce an adequate output pressureand capacity.

Referring to FIG; 3 of the drawings, there is shown therein an alternative arrangement for controlling pressure within the chamber 48 of the housing section El, and at the same time intensifying the vacuum control action of the unit. The modification shown in FIG. 3 is, of course, equally applicable'to the embodiments of the invention shown in FIGS. 1 and 2.

In. this alternative form, the only change in reference to whatis shown in FIGS 1 and 2 is a very simple one, consisting of. the fact that the stud which secures the diaphragrns 27 and 2s together, being specially designated 94, is provided with an internal axial bore of very small diameter throughout its length. The stud 94* receives nuts 96, 97 to secure the diaphragms 27, 28 to spacer 3G, and it projects to the left for mechanical engagement and actuation by the contact dish 33 of primary diaphragm 22. Its right hand end is engageable with the button, 49; of switch 47.

I'The effect of the bore 9% of stud 94 is to communicate the. secondary or vacuum chamber 24. with the chamber 43in which switch 47 is disposed. As the result of this, the, vacuum: in chamber 24, acting on diaphragm 27 in a direction to shift the latter to the left, is at the same time" effective in chamber 48 'on the diaphragm 28, of larger exposed size than the diaphragm 27, to overcome the. first mentioned vacuum eflect and as a result urge the diaphragm. unit 26 to the right, as viewed in FIG. 3.

Thus, the relatively slight'eflect of the vacuum on the diaphragm 27 in opposition to its effect on primary diaphragm 22 is overbalanced, and a diiferential in vacuum responsive force is added to the force, of vacuum on primary diaphragm 22, the diaphragms 22 and 28 working in the same direction to hold switch 47 closed until pumping 1138136811 thoroughly completed. Of course, in a control equipped with the; improvement of PEG. 3, the port or passage 52 in casing. member 21 will be eliminated, and the chamber 45 will be sealed, from atmospheric pressure.

What I claim as. my invention is:

l. A. control for a pump comprising a control unit including first and second flexible, pressure responsive devices having areas of eflective flexibility facing and at least in-part defining a vacuum chamber, and being movable in opposite directions in. response to evacuation of said chamber, said second device having a further area of efiective flexibility spaced from and facing oppositely of said vacuum chamber, means coacting with said second device in defining. a sealed chamber on the side of said further area thereof remote from said vacuum chamber, and a control device actuable by said devices in response to evacuation of said vacuum chamber, said control unit having means placing said vacuum and scaled chambers in. communication with one another, thereby subjecting said second device to vacuum on both of its areas.

. 2. A control for a pump comprising a plural-diaphragm control unit including first and second flexible, pressure responsive diaphragm. devices having areas or effective flexibility facing and at least in part defining a vacuum chamber, and being movable in opposite directions in re sponse toevacuation of said chamber, said second diaphragm device having a, further area of effective flexibility spaced from andof larger area than its area facing said chamber, means coacting with said second device in defining a sealed. chamber on the side of said further area thereof remote from said vacuum chamber, and a control device actuable by: said diaphragm devices in response to evacuation. ofi said vacuum chamber, said control' unit havingmeans placing-said v-acuurnand sealed chambers in communication withone another; thereby subjecting said second device: to vacuum on both of its areas.

3. A control for a pumpcomprising a plural-diaphragm control unit including first and second flexible, pressure responsive diaphragm devices having areas of effective flexibility facing and at'least in part defining a vacuum chamber, and being movable in opposite directions in response to evacuation of said chamber, the opposite sides of the first device at least partially defining a hydrostatic pressure chamber opposite said vacuum chamber, said second diaphragm device having a further area ofeifective flexibility spaced from and of larger area tlianits area facing said chamber, means coacting with said second device in defining a sealed chamber on the side of said further area thereof remote from said vacuum chamber, and a control device actuable by said diaphragm devices in response to pressurization of. said hydrostatic pressure chamber and evacuation of said vacuum chamber, "said control unit having means. placing said vacuum and sealed chambersin communication with one another, thereby subjecting said second device to vacuum on both of its areas.

4. A control for a pump comprising a plural-diaphragm control unit. including first and second flexible, pressure responsive diaphragm devices having areas of elfective flexibility facing and at least in part defining a vacuum chamber, and being movable in opposite directions in response to evacuation of said chamber, said second diaphragm device having afurther area of effective flexibility spaced from and facing oppositely of said vacuumv chamber, means coacting with said second device in defininga sealed chamber on the side of said further area thereof remote from said vacuum chamber, and a control device in said sealed chamberactuable by said diaphragm devices in response to evacuation of said vacuum chamber, said control uni-t having means placing said vacuum and sealed chambers in communication with one another,. thereby subjecting said second device to vacuum on both of its areas.

5. A control for a pump comprising a plural-diaphragm control unit. including first and-second flexible, pressure responsive diaphragm devices having areas of effective flexibility facing and. at least in part defining a vacuum chamber, and being movable in opposite directions in response to evacuation of said chamber, the oppositev sides. of the first. device at least partially defining a hydrostatic. pressure chamber opposite said vacuum chamber, said. second diaphragm device having -a further area of eiiective' flexibility spaced. from. and of larger area than its. area facing, said. chamber, means coacting with said second. .de. vice in defining a sealed chamber on the side ofsaid further area. thereof remote from said. vacuum chamber,- and a control. device in said sealed chamber actuable by said. diaphragm. devices in response to pressurization of. said hydrostatic pressure chamber and evacuation of said vacuum chamber, said control unit having means placing said vacuum and sealedchambers in communication with one another, thereby subjecting said second device to vacuum on both of its areas.

6. A pump control in accordance with claim 5 in which said second diaphragm device comprises a pair of spaced flexible diaphragms at least partially defining therebetween a pressure chamber having a pressure transmitting connection in communication therewith.

7. A control fora motor driven pump, comprising fluid pressure responsive means including elements at least in part defining chambers including a first static pressure chamber, a second vacuum chamber, and a third pressure chamber, and pressure transmitting means connected to said three chambers and adapted to place the same respec-- tively in. fluid pressure communication with a hydrostatic pressure, with a partial: vacuum, and with a.- hydrodynamic:

diaphragms respond to change in pressure, said control unit further comprising a control device operated by said pressure responsive means.

8. A control in accordance with claim 7, in which said last named means comprises at least two vertically elongated tubes extending upwardly to saidcontrol.

9. A control for an electric motor driven pump, comprising pressure responsive means including a first flexible diaphragm at least in part defining chambers including a first static pressure chamber, and a pair of diaphragms at least in part defining a second vacuum chamber and a third pressure chamber, said elements being movably responsive to pressure changes in said chambers, pressure transmitting means connected to said three chambers and adapted to place the same respectively in fluid pressure communication with a hydrostatic pressure, with a partial vacuum, and with a hydrodynamic pressure, and a control device operable by said pressure responsive means as said pressure in said chambers.

10. A control in accordance with claim 9, in which said last named means comprises at leasttwo vertically elongated tubes extending upwardly to said control.

11. A control for a sump or like pump, comprising a housing structure having a first flexible diaphnagm therein coacting therewith in defining a first hydrostatic pressure chamber, said chamber having means to communicate the same with, and subject said diaphragm to, a hydrostatic pressure, said housing structure having therein a control chamber and a control unit in said control chamber, a flexible diaphragm device separating said control chamber from said hydrostatic pressure chamber and coacting with said housing structure to provide a second hydrodynamic pressure chamber therein, said last named chamber having means to communicate the same with a hydrodynamic pressure and thus subject said diaphragm device to said last named pressure, said diaphragm device being engageable by said first diaphragm upon hydrostatic pressure fiexure of the latter and engaging said control unit to operate the same, said diaphragm device maintaining said last named engagement under hydrodynamic force in said second chamber.

12. A control for a sump or like pump, comprising a housing structure having a first flexible diaphragm therein coacting therewith in defining a first hydrostatic pressure chamber, said chamber having means to communicate the same with, and subject said diaphragm to, a hydrostatic pressure, said housing structure having therein a control chamber and a control unit in said control chamber, a flexible diaphragm device including spaced, second and third flexible diaphragms separating said control chamber from said hydrostatic pressure chamber and coacting with said housing structure to provide a second, hydrodynamic pressure chamber therein between saidisecond and third diaphragms, said last named chamber-having means to communicate the same with a hydrodynamic pressure and thus subject said second and third diaphragms of said diaphragm device to said last named pressure, said diaphragm device being engageable by said first diaphragm upon hydrostatic pressure flexure of the latter and engaging said control unit to operate the same, said diaphragm 1O device maintaining said last named engagement under hydrodynamic force in said second chamber.

13. A controlfor a sump or like pump, comprising a housing structure having a first flexible diaphragm therein coacting therewith in defining a first hydrostatic pressure chamber, said chamber having means to communicate the same with, and subject said diaphragm to,

a hydrostatic pressure, said housing structure having therein a control chamber and a control unit in said control chamber, a flexible diaphragm device including spaced, second and third flexible diaphragms separating said control chamber from said hydrostatic pressure chamber and coacting with said housing structure to provide a second, hydrodynamic pressure chamber therein between said second and third diaphragms, said last named chamber having means to communicate the same With a hydrodynamic pressure and thus subject said second and third diaphragms of said diaphragm device to said last named pressure, one of said second and third diaphragms being of greater effective pressure responsive area than the other, said diaphragm device being engageable by said first diaphragm upon hydrostatic pressure flexure of the latter and engaging said control unit to operate the same, said diaphragm device maintaining said last named engagement under a diflerential in hydrodynamic force in said second chamber on said second and third diaphragms'.

14. A control for a sump or like pump, comprising a housing structure having a first flexible diaphragm therein coacting therewith in defining a first hydrostatic pressure chamber, said chamber having means to communicate the same with, and subject said diaphragm to, a hydrostatic pressure, said housing structure having therein a control chamber and a control unit in said control chamber, a flexible diaphragm device including spaced, second and third flexible diaphragms separating said control chamber from said hydrostatic pressure chamber and coacting with said housing structure to provide a second, hydrodynamic pressure chamber therein between said second and third diaphragms, said last named chamber having means to communicate the same with a hydrodynamic pressure and thus subject said second and third diaphragms of said diaphragm device to said last named pressure, the diaphragm of said second and third diaphragms which is adjacent said control chamber being of greater effective pressure responsive area than the other, said diaphragm device being engageable by said first diaphragm upon hydrostatic pressure fiexure of the latter and engaging said control unit to operate the same,

said diaphragm device maintaining said last named engagemeut under a difl'erential in hydrodynamic force in said second chamber on said second and third diaphragms.

References Cited in the file of this patent UNITED STATES PATENTS 2,488,506 Bernhardt Nov. 15, 1949 2,537,474 Mejean Jan. 9, 1951 2,635,546 Enyeart et al Apr. 21, 1953 2,730,591 -Nielson Ian. 10, 1956 2,804,516 Staak Aug. 27, 1957 2,834,845 Nielsen May 13, 1958 2,910,003 Kaatz Oct. 27, 1959

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