US3077163A - Liquid ejectors - Google Patents

Description

Feb. 12, 1963 R. A. EYMAN 7,

LIQUID EJECTORS Filed May 15, 1958 4 Sheets-Sheet 1 INVENTOR Ralph/4. Eymam BYQ.

li/S ATTORN EY 4 Sheets-Sheet 2 R. A. EYMAN L'IQUID EJECTORS E M 0| 1 J :E ill:

l Hlm z M??? 1" Feb. 12, 1963 Filed May 15, 1958 I NVENTOR liaafi A. Eymam CQWW fi/Is ATTORNEY Feb. 12, 1963 R. A. EYMAN 3,077,163

LIQUID EJECTORS Filed May 15, 1958 4 Sheets-Sheet 3 P K 79 3 x? INVENTOR Ralph A. Eyman,

BYQQQ ms ATTO RN EY Feb. 12, 1963 R. A. EYMAN LIQUID EJECTORS 4 Sheets-Sheet 4 Filed May 15, 1958 FL I Ralf/Z A Eyman INVENTOR M /l/; ATTORNEY United StatesPaten't ()fitice 3,077,153 Patented F eb. 12, 1963 3,077,163' LIQUID EJECTORS Ralph A. Eyman, Miami, Fla, assignor to Ralph E. Carter Company, Hackensaclr, N.J., a corporation of New York Filed May 15, 1958, Ser. No.'735,66 1

. 25 Claims. .(Cl. 103-448) The present invention relates to improvements in pneumatic pumping systems, and more particularly to pumping apparatus operating with a compressed aeriform medium for'periodically lifting to a' higher level liquids, or liquids mixed with solids, which are accumulated in a receptacle. The improved system is particularly suitable for use in many types of sewage ejectors even though the field of its' sistbasically of a receiver having a fixed capacity to ac-.

cumulate the intermittently flowing liquids, or liquids mixed with solid matter, and of an apparatus for periodically evaluating the receiver by lifting its contents to a higher level. The receivers, also' called pots, are'eq'uipped with suitable actuating devices which latter may be responsive to the combined weight of the receiver and its contents, or may be so installed as to set the evacuating apparatus into operation when the liquid in the receiver reaches a predetermined highest level. Many known ejector systems, as well as the apparatus of this invention, utilize a compressed aeriform medium which, by being released in to the receiver, expels the liquid contents through suitable discharge piping to a higher level, whence the sewage may continue its gravity flow to the treatment plant or into another receiver, if necessary.

I According to a more recent proposal disclosed in Patent No. 2,656,794 granted on October 27, 1953, the receiver is in the form of a length of pipe through which the raw sewage is led, and the controls for evacuating apparatus are'mou'nted directly in the piping. Tn is patent further proposes the use of an actuating device for'the evacuating system which is responsive to changes in liquid level, and of a holding device whose purpose. is to maintain the actuating device in operation within a predeterrnined pressure range in the collecting piping. However, when a compressed gas is introduced into the system at a rela tively slow rate, the liquid level in the collecting piping drops below the actuating device and rises a proportional amount in the discharge piping. Assuming that the gas is, introduced at a rate slow enough to create anegligible bacsi pressure, the difference between the liquidlevels in the collecting and discharge piping may be so slight that the lower limit oi the pressure range within which the holding device operates may never be reached. If, on the other hand, compressed gas is introduced at a rate fast.

enough to create dynamic back pressures higher than the lower limit of pressure range within which the holding device operates, temporary surges of short duration will occurin most cases whereupon the pressure drops below the lower limit of the required pressure range. The result in both instances is useless cycling and irregular pulsating operation of the patented apparatus.-

According to a further proposal in the aforementioned patent, the control system may consist of an air compressor, a starting device actuatable by the liquid at a predetermined level in the collecting piping, and a timing arrangementwhich latterkeeps the compressor in opera l vice shuts off the supply of compressed gas.

tion for a predetermined period of time considered sumcient to eject all or essentially all of the material collected in the piping. Such systems could be considered satisfactory in instances when the pumping device need not operate against substantial back pressure. In a pumping station with pressurized lines, however, such. pumping devices whose controls include merely a starter and a timer are unsatisfactory because the conditions in pressurized lines are unpredictable and, if a gas is introduced for a predetermined period of time, it may fully evacuate the receiver in one instance but will'cause only partial evacuation in other instances when the pressure conditions in the lines change.

An important object of the present invention is to provide a control apparatus for evacuation of receivers in liquid ejectors which insure complete evacuation of accumulated liquids irrespective of pressure fluctuations in the receiver.

Another object of the invention is to provide a control apparatus of the above described character which is responsive to the pressures prevailing in the receiver only after elapse of a fixed time period subsequent to the start of liquid evacuation.

' An additional object of the invention is to provide an apparatus of the above described character whose'opera tion is fully automatic and which may be installed with equal efiiciency insystems employing a pot or a pipe as the liquid collector. V

A further object of the invention is to provide an ap paratus adapted to evacuate a sewage receiver which is of simple construction, which'is fully automatic, and which may be installed in existing ejectors.

A still further object of the invention is to provide in a pumping apparatus of the above characteristics an inlet trap so located with respect to the receiver that the uni' flow valve, which normally prevents entry of additional liquids during the evacuation cycle, seals against liquids rather than against gases.

The improved system consists essentially of a starting device so mounted as to be actuatable by the liquid in a receiver at a predetermined uppermost level in the latter, a source of compressed aeriform medium, piping connecting the source of compressed aeriform medium with the receiver, and a control mechanism operable by the starting device in such a way as to introduce a coinpressed gas into the receiver when the latter filled with liquid to a predetermined level. The control arses:

anism is coupled with a suitable time delay which main tains the supply of compressed gas into the receiver for a fixed time period regardless of the pressures prevailing in the receiver, and with pressure-responsive means which latter stops the c'ontrol apparatus after the time delay; has already completed its operation, i.e. after the condi tions in the liquid receiver are sufiiciently settled to permil: consistently uniform reduction in pressure therein to' the lowermost level at which the pressure responsive'de- Thus, the pressure responsive means becomes effective only after the initial and oftenunbalanced conditions in the receiver, arising from sudden introduction of a compressed gas, are sufficiently controlled and stable so that the subsequent reduction in pressure, preferably close to atmospheric pressure when the liquid receiver is sufficiently evacuated, is always uniform and the pressure responsive means actually turns off the apparatus at a time when the receiver is empty. The receiver. is then connected to atmoshere and the one-way control device in the inlet piping permits renewed inflow of liquid material into the receiver to fill the latter to a predetermined maximum level when the liquid evacuating cycle is repeated in the. same way.

As it is well known that a valve will seal better against a liquid than against an aeriform medium, the invention provides an inlet trap in and adjacent to the tcrmmal of inlet piping leading the liquid into the receiver, and the customary inlet check valve is then located on the upstream side of the trap, whereby, upon introduction of a compressed gas into the receiver, the liquid in thetrap is forced .against the check valve to seal same effectively while the evacuation of liquid'takes place.

The time delay may be of varied designs. For example, an electric control system employing time delay relays may be used, or a delay operating with a liquid medium may be employed. The pressure-responsive device which shuts oil the supply of compressed gas may be a valve of known construction, for example, a diaphragm valve or the like, and is so coupled with the line leading to the source of compressed gas as to interrupt the flow of gas into the receiver at a predetermined minimum pressure prevailing in the receiver after the time delay has completed its operation.

The starting device which triggers the operation of my novel apparatus may be- (a) A float of known construction disposed close to the top of the receiver so that the liquid lifts the float and thereby opens the path for compressed gas at a predetcrmincd maximum level in the receiver; or

(b) An electrode extending into the receiver so that the liquid, upon reaching its uppermost level, closes a path between the electrode and, for example, a grounded wall of the receiver to energize one or more relays which latter, due to the provision of suitable holding circuits, remain energized even after the electrode is out of contact with the descending liquid material.

As before stated, the novel system is equally applicable to ejector systems employing a sewage collecting pot or those employing a length of pipe for collecting .theliquid materials. in the following more detailed description of my invention and in the claims, the term receiver is intended to embrace either a pot or a length of piping whenever a receptacle for liquids is referred to.

Since the starting and the pressure-responsive apparatus may be installed in immediate proximity of each other, the liquid evacuating apparatus may be designed as a very compact unit and thus requires little room for its installation. If electric current is not available, the apparatus may be constructed with a hydraulic time delay and may use a constant source of compressed gas located at some distance from the ejector which source may be connected with more than one ejector. The hydraulic delay preferably consists of a novel assembly specially designed for use in liquid ejector systems of this invention and may be integrally coupled with the pressure-responsive device in such a way as to prevent the latter from shutting off the supply of compressed gas for a fixed time interval starting from the moment when the gas is first introduced into the receiver.

Many additional features, advantages and attributes of my improved apparatus for evacuating liquids or mixtures of liquids and solids to a higher level wi'l become apparent in the course of the following detailed description of certain embodiments selected for illustration in the accompanying drawings, and the true scope of my invention will be pointed out in the appended claims.

In the drawings,

FIG. 1 is side elevational View in partial section of one form of the expanding-gas ejector;

FIG. 2 shows a hydraulic control apparatus for the ejector system illustrated in FIG. 1;

FIGS. 3 and 4 illustrate two forms of electrically operated control apparatus; and

FIG. 5 shows a modified expanding-gas ejector in which the pot is replaced by a length of pipe.

Referring now in greater detail to the illustrated embodiments,'and first to FIG. 1, there is shown a liquid ejector pump 1% comprising an inlet pipe 11, a check" valve 12, an inlet trap 13, an ejector pot 14, a discharge trap 16, gas expansion pipe 17, a discharge pipe 18, gas supply conduit 1%, controls actuating element 20, and a gas release chamber 21. The gravity main 22 forms no part of the pump; it receives the liquids or the mixture of liquids and solids lifted by the pump 10 from its pot 14 through pipes 17 and 18 by means of compressed gas entering the system through the supply conduit 19 and escaping into the gas release chamber 21. The element 20, representing but one form of the actuating means for the control apparatus, is shown in greater detail in FIG. 2 further illustrating the hydraulic time delay system for introduction of compressed gas into the supply conduit 19.

At the beginning of an operating cycle, a small quantity of liquid remains in the discharge trap 16 from the previous cycle, filling the discharge trap 16 to the approximate level indicated by line A-A. Liquid from the previous cycle also fills the inlet trap 13 to the approximate level of line B B. New liquid, for example, raw sewage, flows by gravity into and through the inlet pipe 11 and fills the pot 14 and gas expansion line 17 up to the level indicated by line CC. During this filling stage of the cycle, the air which is displaced by the liquid in pot 14 is free to escape into atmosphere through the open line 19. On the downstream side of discharge trap 16, i.e. in the lower part of the gas expansion pipe 17, the air displaced by the rising liquid is free to escape through the discharge line' 18 and into the gas release chamber 21 which, too, is open to atmosphere.

As the liquid level rises toward line C-C, the liquid lifts element Ztl which, when the level C-C is reached, directly or by remote control, closes the gas pipe 19 to atmosphere and introduces compressed gas therethrough. The gas penetrating into the pot 14 exerts suificient pressure against the liquid in inlet trap 13 to close inlet check Valve 12 and to force the liquid up the gas expansion line 17 and discharge pipe 18 into the gravity main 22, the gas escaping into the chamber 21. As the inlet check valve 12 is closed, no new liquid can enter while compressed gas is introduced into the pump 1% The liquid level descends to the line DD.

The main advantage of providing an inlet trap is in that the inlet check valve seals much better against liquid than against gas. Thus, compressed gas entering through conduit 19 exerts pressure against the liquid in inlet trap 13,

and the entrapped column of liquid in turn closes the inletcheck valve 12.

The column of liquid in the gas expansion pipe 17 has a slight momentum and continues to rise in said pipe under the influence of advancing compressed gas. However, regardless of this momentum, the gas starts to bubble up and through the liquid and entrains the liquid through the discharge pipe 18. The resulting mixture of gas and liquid in the expansion pipe 17, being lighter than a solid liquid column, reduces the head on gas accumulated in the pot 14. This enables the gas to expand as rapidly as the head is lowered, the head in turn being lowered even more.

as the gas expands, thus creating a chain reaction until the expanding gas has developed enough velocity to carry most of the remaining liquid in the expansion line 17 up and through the discharge pipe 18. The gas continues to escape up and through pipes 17 and 18 until the pressure in the receiver approaches atmospheric pressure when the gas can no longer expand and the small amount of remaining liquid drops back into the discharge trap 16. As the pressure in the pct 14 nearly approaches atmospheric pressure, a device connected to line 31 and responsive to such drops in pressure in the receiver 14 shuts off the supply of compressed gas through pipe 1 and opens the latter to atmosphere to complete the ejection cycle of the pump 10. The pressure at which this device beminimum comes responsive will hereinafter be called the holding pressure. I v

The inlet valve 12 reopens and permits new liquid to enter by gravity feed through the pipe 11 to again fill the receiver 14 up to the level 0-0. The gas expansion and liquid ejection cycles are then repeated as above described.

Results of extensive tests conducted with actual working models indicate that the total time necessary for the completion of the final or gas expansion stage, that is, the interval between that time when the liquid in the receiver reaches level D--D and the time when the pressure drops to or nearly approaches atmospheric pressure, is surprisingly short, lasting from less than one second for low lifts to two or three seconds for higher lifts. The reaction is more violent as the lift, i.e. the difference in levels of pot 14 and gravity main 22., increases. The quantity of liquid remaining in the pump is about the same.

Although, under certain exceptional circumstances, the resulting pressure momentarily reaches atmospheric pressure, in most cases it only rather closely approaches the atmospheric pressure. In every instance, after the remaining liquid drops back into the discharge trap 16, the resulting pressure creates a slight back pressure against the incoming gas before the supply conduit 19 can be shut off to further entry of compressed gas and be opened to atmosphere. The maximum value of such rather slight build-up in back pressure will hereinafter be called the maximum critical pressure. In order to insure proper functioning of the pressure-responsive device, the minimum holding pressure must be equal to or higher than the maximum critical-pressure. However, in order to evacuate the maximum amount of, liquid, the minimum holding pressure must be as close to atmospheric pressure as possible. The-minimum holding pressure then becomes equalto the maximum critical pressure. I

The discharge trap 16 is so designed as to insure that maximum amounts of liquid are pushed up the line 17' to empty pump 10 before the expansion phase of the compressed gas is started. The pump 10 operates best when the gas expansion pipe 17 'is in vertical position though, as shown in FIG. 1, it need not necessarily be vertical. As the inclination of pipe 17 to the vertical increases, the amount of liquid remain ing inthe system atthe endofea'ch liquid evacuating cycle also increases. By.further inclining the pipe,-its angle. to the verticalreaches a critical magnitude when thegas escapes on top of the liquid instead of mixing withit to. reduce its density. By increasing the angle of pipe 17,: its length also increases so that the volume of free gas stored in the pot 14 in proportion tothe physical total volume of the receiver plus that of the expansion pipe 17 becomes less, thus destroying some of the ability of gas to completely expand with sufiicient force and velocity to become eiiective. v The angle indicates the inclination of gas expansion pipe 17 to the vertical. While, and as already stated hereinbefore, the performance of the pump is improved if the line 17 is vertical, under certain circumstances, for example, due to the peculiarities of terrain over which the piping is led. slight or even substantial inclination of pipe 17 to vertical may become necessary.

In FIGS. '2 to 4, there are shown three types of control apparatus for introduction, or cutting off the supply, of compressed gas into the pump 19, as well as for establishing or interrupting the communication between atmos-' phere and the pct 14 for escape of air on the upstream side of the discharge trap.

\ The requirements which this control apparatus must satisfy for proper operation of the above-describedpump system will be best understood by shortly reviewing the op{ eration of the pump. As shown in FIG. 1, the liquid level rises while the infiowing liquid progressively fills the pct 14 until theliquid reaches its maximumlevel indicated by line C-C. The control apparatus not only must be able to actuate one or more devices to shut oii the gas line 19 to atmosphere and to. introduce compressed gas into the system, but also to maintainsuch device or devices in operative position until the receiver is fully evacuated regardless of the pressure conditions prevailing therein since the drop in gas pressure to minimum holding pressure should occur only when the ejection cycle of the pump is completed; otherwise, too much liquid would remain which would considerably reduce the efiiciency of the system.

The control apparatus is actuated by the liquid at a certain level and is held in operative position by the back pressure exerted by liquid against the incoming compressed gas. This back pressure will hereinafter be called holding pressure. The control system is released, i.e. returned to inoperative position, when the holding pressure is so reduced that it reaches its minimum value. However, the control system can be released only after having been held in operative position by a suitable time delay for a fixed period of time regardless of pressure conditions prevailing in the receiver. This is necessary because, in the very instant when a compressed gas is intro duced slowly into the receiver 14, the liquid level immediately drops below line C--C and thus permits descent of the sensing device 20 while the liquid level rises only slightly in the gas expansion pipe 17. The resulting static back pressure acting through conduit 31 is so close to atmospheric pressure to be below the minimum holding pressure, and thusdoes not afiect the pressure-responsive device sufficiently to maintain the latter in a position in which it introduces compressed gas intothe pump system. The timedelay is also necessarywhen'the compressed gas is introduced at a higher rate sufiicient to cause asurge in: the mass of liquid, followed immediately by a drop in pressure below the-minimum holding pressure. Without such a time delay, the pressure-responsive device would automatically cut oli the supply of compressed gas to the pump system immediately after the surge when the drop in pressure below the minimum holding pressure occurs.

However, in the unique case when the compressed gas is introduced at exactly such a rate as to immediately create a back pressure higher than the minimum holding pres sure and to uniformly accelerate the mass of liquid to maintain a dynamic back pressure without surges and sub sequent pressure drops-below the minimum holding pressure, the control system can operate in a threestage cycle asfollowszw I i l x In the firststage, the liquid actuates the control-apparatus by (a) physically displacing an actuating member bymeans of a bell (FIGS. 1 and 2), a float, or another liquid displacing body; or by (b) contacting an electrode and completing an electrical circuit (FIGS. 3 and 4).

In the second stage of the cycle, the control apparatus is held in operative position by dynamic back pressure.

In the last stage, the control apparatus is released by reducing the dynamic back pressure below the holding ressure, i.e. below the pressure required to maintain the control apparatus in such position that the latter permits introduction of compressed gas into the pump system.

To eliminate the effects of all unknown and uncontrollable factors, a 'fourth stage is now introduced between the first and the'second stages above referred to, along with a fifth stag'e' between the above-mentioned second and third stages.- The influence of such unknown and uncon-i trollable factors is eliminatedby' the aforementioned time delay device which maintains the first stage (completion of electrical circuit or actual displacement oi a float or the like) until the pressure, in accordance with the requirements of the second stage, is built up sufiiciently to reach the desired holdingpressure with only static pressures; The control system then operates in a five-stage cycle as follows: r

First stage is the same as above.

In the second stage, the time delay device maintains the elements in the position they assumed in the first stage.

In the third stage, static back pressure further maintains the elements of control apparatus in theposition's they atesurned-inthefirst two stages.--- I In the fourth stage, the time delay is released.

Finally, in the last stage, as in the third stage hereinbefore described, the control system is released by reducing the back pressure below the holding pressure.

The sensing or starting device of the hydraulic control system of FIG. 2 is shown installed in the pct 14 of pump 10 which is illustrated in FIG. 1, it being understood, however, that it can be used in the control chamber 26 of the modified pump 10:: shown in FIG. without any modifications. Similarly, the electrical sensing or starting devices illustrated in FIGS. 3 and 4 as forming part of the pump system It can be used in the pump a; this will be readily understood as the description proceeds.

The sensing or starting device 20 is in the form of a bell which is fastened to the lower and externally threaded end of actuating element or stem 23 of pilot valve 27 by means of nuts 29,. 30. Valve 27 forms part of the control system for introducing compressed gas into the receiver. A back pressure line 31 communicates with the interior of pot 14; its pilot branch 32 is connected with the pilot valve 27, and its time delay branch 33 connects the line 31 with the upper end of time delay 34 whose cylinder 35, is integral with the housing of valve 27. The time delay 34 further comprises a piston 36, poppet system 37, poppet 38, liquid delaying medium 39, and a seal 4t). The control system further comprises a pilot gas pressure line 41, a pilot-actuating gas line 42, and a main valve 43. The latter comprises an actuating member or stem 44, a diaphragm 45' (replaceable by a piston), and weight or weights 46.

It will be noted that only pct 14, bell 20 and the time delay 34 are shown in section, the pilot valve 27 and the main valve 43 being commercially available devices of known construction. Pilot valve 27 is a three-way spool valve with a mid-point neutral position in which all three ports (indicated by letters C, P and E) are closed at the same time. The stem 28 is shown approximately midway between its two extreme positions. The markings C, P and E shown .on the pilot valve 27 are designations well known and accepted in industry for this type of three-way valve and dasignate the cylinder side C, the pressure side P, and the exhaust side B, respectively, of the valve. When the valve stem 28 is in down position, the C side is open to the E side, and the P side is closed. As the stem 28 travels in upward direction, it shuts off side C to side E before opening side C to side P in the up position.

The main valve 43 is of similar construction with the exception that it is usually larger and its stem 44 is actuated by a diaphragm 45 which, as before stated, may be replaced by a piston (not shown) to move the stem 44 in upward direction. The weight or weights 46 cause the stem 44 to descend when no pressure is applied against the underside of diaphragm 45. The C, P and E designations have the same meaning as those applied to pilot valve 27.

The friction in the valves is rather negligible and, therefore, need not be taken into account in the following description of operation of the control system shown in FIG. 2. The weight of element 46 plus the weight of the stem 44 are equal to the effective area of diaphragm 45 times the minimum holding pressure of pump 1%. Time delay 34 is actuated by the valve stem 28 which latter is directly connected with the poppet stem 37. Poppet stem 37 is free to slide in the piston 36 which in turn is loosely slidable in the cylinder 35. There is an annular clearance 47 between the periphery of piston 36 and the inner wall of cylinder 35. The sliding movement of the piston-36 with respect to poppet stem 37 is very short and is limited on one side by the valve stem 28 which defines a shoulder 48, and on the other side by the poppet 38. Piston 36 has bypass apertures 49 which allow the liquid delaying medium 39 to pass from the underside of piston 36 when the piston rests against shoulder-48 onthevalve stem 28. If the piston rests against the poppet 38, the latter closes apertures 49. and

thus prevents communication of medium 39 to the upper side of the piston. When the valve stem 28-is in its down position, piston 36 rests against the face 50 of cylinder 35. As the pilot valve stem moves in upward direction, its shoulder 48 engages and entrains the piston 36, thus opening the lower terminals of apertures 49-to permit the passage of liquid delaying medium 39 from the upper side to the underside of the piston. The liquid delaying medium 39 otters little resistance to the travel of piston 36.

When the valve stem 28 reaches the upper end of its stroke and thereupon begins to descend underits own weight, as well as under the weight of poppet stem 37, poppet 3S and bell 20, the slight resisting force of liquid delaying medium 39 holds the piston 36 in its uppermost position until the poppet 38, traveling with valve stem 23, engages the upper face of the piston and closes the upper terminals of apertures 49. To permit further travel of the valve stem 28 in downward direction, liquid delaying medium beneath the piston 36 must be displayed by flowing about the periphery of latter through the annular clearance 47. This clearance is small enough to offer relatively high resistance to the flow of said medium, thus slowing down the movement of valve stem 28 at such rate as to suificiently delay the opening'of the C side to the E side in pilot valve 27.

While the pump 10 is filling, i.e. while the valve 12 shown in FIG. 1 is open, the displaced gas flows from the pot 14 and through the gas pipe 19 into the main valve 43 and to atmosphere through the exhaust side E which is open to the cylinder side C.

Side P of the main valve 43 is then closed. The stem 28 of pilot valve 27 is in its down position with its side C open to side E, and the side P closed. As the liquid level rises in the pot 14, it entraps a certain quantity of air in the bell 20. For all practical purposes, and by neglecting friction, the force necessary to move the stem 28 of pilot valve 27 equals the combined weight of the valve stem and of bell 20 so that the bell must displace an amount of liquid whose weight equals the combined weight of the bell'and valve stem 28. This is achieved when the liquid level reaches line C-C which is below the lower terminal of gas pipe 19. Thus, the pilot valve 27 always operates beforethe liquid could reach the terminal 51. Should there be a failure in gas supply and the liquid level would continue to rise, it will, upon reaching the terminal 51, rise in the pipe 19 but not in the pot 14 since the only path for escape of gases from the pot 14 is then closed at the E side of pilot valve 27. In this manner, floating solids are prevented from reaching the top of hell 26. Such solids carried by the liquid, for example, raw sewage, would add to the overall weight of the bell 24 plus valve stem 28 and would thus upset the operation oi the control apparatus.

When the pilot valve stem 28 is moved into up position, i.e. when under normal operating conditions the liquid level in the pot 14 reaches line C--C, side C of pilot valve 27 is closed to side E, and the side C is open to side P. The compressed gas in line 52 is permitted to pass through pilot gas pressure line 41, from the P side to the C side of pilot valve 27, and through pilot actuating gas line 42 to actuate the main valve 43 by acting against the underside of diaphragm 45 to lift the valve stem '44 against the action of weight 46. Side P in the main valve 43 is then open to side C to permit compressed gas in line 52 to enter conduit 19 and therethrough into the pot 14. The side C of main valve 4 is then closed to side E.

While the gas is building up a back pressure equal to or greater than the minimum holding pressure in pot 14, pilot valve stem 23 is held in up position by time delay 34 and descends only slowly to down.position in which the side P of valve 27 is, shut on and side C opensv to side E, allowingback pressure instead of press sure in line 52 to hold the stem 44 of main valve 43 in up position.

In its simplified form, and in accordance with the disclosure of aforementioned Patent No. 2,656,794, the control apparatus of FIG. 2 can also operate without the time delay 34. The stem 28 of pilot valve 27 then descends together with the liquid level. The main drawback of such simplified construction is in that the pressure responsive device may interrupt the gas supply at a time when the receiver is only partly evacuated. In either case, the back pressure line 31 with its branch line 32 equalizes the pressure at both sides of the pilot valve stem 28, so that the forces resulting from the pressure times the cross-sectional area of the stem which act in opposing directions cancel each other and do not affect the operation of pilot valve 27.

When the back pressure is reduced to a point below the minimum holding pressure, stem 44 of the main valve descends under the influence of its own weight plus that of weight 46, and closes side C to side P while opening side C to side E of main valve 43. This completes the cycle and the air is again free to escape up the line 19 and from side C to side E of the main valve.

ln FIG. 3, there is shown an electrically operated con trol apparatus forthe pump 10 of FIG. 1. This system, too, is adapted to temporarily maintain the supply of compressed gas (e.g., air) to the control chamber 26 of the pump 10a shown in FIG. 5, after the liquid therein has reached a critical level.

The bell 20 shown in FIGS. 1 and 2 is replaced by a control electrode 53 which is insulated from the metallic wall of the pot 14 by a suitable insulating element 54. Electrode 53 is connected through the winding of a relay 55 to a source of current here shown schematically as the negative terminal of a battery 56 whose positive terminal is grounded. A bus bar 57 terminates at the front contact of relay 55 whose armature 55 is likewise connected to the high-voltage terminal of battery 56.

Connected between bus bar 57 and ground are the windings of' a slow-operating relay '3 and of a start relay 59. Armature 65) of relay 59, whose from contact is tied to bus bar 57, is connected to negative battery via an armature 61 and back contact of relay 58 and, in parallel therewith, through a normally open contact 63 of a pressure switch 62 here shown as comprising a diaphragm 64 within a cylinder 65 communicating with the interior of pot 14 by way of a conduit 66; Relay 59 has three further armatures 67, 63, 69 connected to respective terminals of a source 70 of alternating current, here indicated schematically as a three-phase generator; the front contacts associated with these armatures lead to respective phase windings of an A.-C. motor 71.. A compressor 72 driven by motor 71 via a transmission, schematically indicated at 73, supplies air under pressure to a duct 74.

Duct 74 leads into gas pipe 19 by way of a springloaded check valve 77. Ahead of valve 77, a pilot duct 78 branches off from duct 74 and leads to a normallyopen two-way diaphragm valve 79 controlling an outlet port 19' of pipe 19.

When the liquid in pot 14 has risen sufficiently to contact the electrode 53, it closes a high-resistance path between this electrode and the grounded wall of the pot, thereby energizing the highly sensitive relay 55. This relay attracts its armature 55 and connects bus bar 57 to the negative terminal of battery 56. Start relay 59 is now energized, but relay 58 connected in parallel with relay 59 is slow to respond so that a holding circuit forrelay 59 is closed via its armature and armature 61 to negative battery. Relay 59, at armature 67, 68, 69, also connects power to motor 71 which now drives the cornpressor 72, whereby air under pressure is admitted through check valve 77 into gas supply pipe 19 and through pilot duct 78 to valve 79, the latter operation lid shutting off pipe 19 from the atmosphere by closing the duct 19'. As the liquid level in pot 14 begins to drop, relay 55 releases but relay 59 remains operative over its previously traced holding circuit.

Before the slow-operating relay 55 has yet attracted its armature 61, the back pressure in pot 14 has built up sufliciently to cause the operation of pressure switch 62 which closes the contact 63, thereby maintaining the holding circuit of relay 59 even after relay 58 has operated. "this holding circuit is broken only when the pressure in pot 1% has dropped below its critical value, the resulting release of relay 59 deenergizing motor 71 to restore the system to its quiescent condition.

The circuit of FIG. 4 is similar to that of FIG. 3, except that relay 59 has been replaced by a relay 80 having a single armature 81. Motor 71 of FIG. 3 has been omitted, fiuid under pressure having been assumed to enter the duct 52 from a suitable source (not shown) as in FIG. 2. A solenoid 82 is connected between bus bar 57 and ground, this solenoid controlling the stern of a pilot valve 83; the latter valve is inserted between a pilot duct 84 which branches ofi from main gas line 52, and a conduit 85 leading toward the main valve 43 to control its operation in the manner desiribed for pilot valve 27. and main valve 43 of FIG. 2.

In operation, the rise of the liquid in pct 14- toward electrode 53 again results in the operation of relay 55 which energizes the relay 8%) and, after an interval, the slow-operating relay 58 as previously described. Relay 80, in attracting its armature 81, closes its aforedescribed holding circuit and maintains bus bar 57 connected to negative battery independently of relay. Before relay 58 has operated to open the holding circuit of relay 80, armature 61 has been shunted by contact 63 as a result of the operation of pressure switch 62. Solenoid 82, operating in parallel with relay 8t}, admits gas from duct 52 into pipe 19 and maintains its operative position until the back pressure in pot 14 has dropped sufliciently to deactivate the switch 62 and to restore the circuit to normal. In FIG. 5, there is illustrated a liquid evacuation pump 18a which is quite similar to that shown in FIG. 1, with the exception that the inflowing liquid is stored in a control chamber 26 and in a receiver pipe 15 which thus replace the pot 14.

The operation of pump Ida is identical with thatof the previously described pump 10. Thus, liquid enters through inlet pipe 11a and valve 12a to fill the lines 11a, 15 and 17a, as well as chamber 26 up to the level C'-C when the control element 26a becomes operative to close line 19a to atmosphere and introduce compressed gas therethrough. Control element Zila schema tically represents either the bell 26 (FIGS; 1 and '2) or the electrode 53 shown in FIGS. 3 and 4. The liquid under pressure in inlet trap 13a then closes valve 12a while the compressed gas expels the liquid frorn chamber 26 and line 15 through discharge trap 16a and lines 17a, 18a into the gravity main 22a. Spent gas is free to escape through discharge chamber 21a. When the liquid level is reduced to line DD', after which the gas expansion takes place, nearly atmospheric pressure prevails in the chamber 26 and line 15 which causes the element Zila to open line 19a to atmosphere and to interrupt the supply of compressed gas therethrough; Lines A'--A' and B indicate the initial levels of liquid in the respective traps 16a and 13a.

7 It has been discovered that the shape and inclination of certain hereinabove described parts greatly influence the operation of the pump 10a. Thus, the diameter and slope of receiver line 15; the curvature of control chamber 26 at points 23, 24 and 25; as well as the inclination, if any, of gas expansion pipe 17a from the .vertical affect the operation of the pump. The inclination of receiver line 15 and the shape of control chamber 26 in areas indicated by numerals 23 to 25 are important for the maximum rate of flow of liquid which can pass throughthe inlet pipe 11a. The receiver 15 must be of such diameter and slope that the maximum flow of incoming liquid only partially fills its cross-sectional area, thus allowing the airto escape in a direction opposite to the liquid how when the line is filling. In other words, when the check valve 12a is open, air must be free. to flow from receiver line 15 into the control chamber 26 and thence into and through the line 19a which is open to atmosphere. For the above reason, the diameter of receiver line 15 preferably is at least one pipe size larger than the diameter of inlet line 11a.

The shape of control chamber 26 in the areas indicated by numerals 23, 24 and 25 is so chosen as to allow liquid at this rate of flow to pass through the chamber 26 without bunching up, as the accumulated liquid would hinder the escape of gas from receiver line 15 into the control chamber 26. At 24, the piping expands and is broader than the inlet piping 11a, enabling the incoming liquid to spread out as it passes thereover. At 23, the chamber '26 curves upwardly to allow unimpeded passage of gas. The velocity of incoming liquid increases by gravity as it flows over area 25, which reduces the contained vertical head of the liquid.

As is described and claimed in the hereinbefore mentioned United States Patent No. 2,656,794, an advantage of the system shown in FIG. is in that it requires no separate ejector pots since the liquid assemblies in the receiver line 15 which forms part of the piping for conveying the liquid from a lower to a higher level. This system requires no check valve at the discharge end of the receiver. Substantial quantities of liquid, accumulated in the line 15 between traps 13a and 16a, may be lifted to a higher level within a very short period of time, as above mentioned in connection with the pumping apparatus shown in FIG. 1.

The invention is, of course, not limited to the exact details of construction illustrated and hereinabove described, but may be embodied in a number of further modifications within the spirit and scope of the appended claims.

I claim:

1. A pneumatic pumping apparatus comprising, in combination, a receiver; conduit means connected to said receiver for introducing a liquid into said receiver; one-way valve means in said conduit means; piping in communication with said receiver at a lower portion thereof and extending upwardly therefrom; a source of compressed gas; a line in communication with said receiver and adapted to be alternately connected with atmosphere and with said source; control means operatively connected to said line and having a first position in which said line is open to atmosphere and a second position in which said line introduces compressed gas into the receiver to close said one-way valve means and to expel the liquid through said piping; starting means actuatable by the liquid when the latter fills said receiver to a predetermined level causing movements of the control means into said second position; time delay means operatively connected with said starting means for maintaining the control means in said second position for a fixed period of time; and means for moving said control means into said first position in response to a predetermined minimum pressure in said receiver after said time delay means becomes deactivated.

2. In a sewage ejector, in combination: a sewage receiver having an upper portion and a lower portion; conduit means connected to the lower portion of said receiver for introducing sewage therein; one-way valve means in said conduit means; a pipe connected to the lower portion of said receiver and extending upwardly therefrom; a source of compressed gas; a line communicating with the upper portion of the receiver and connected with said source; control means in said line having a first position in which the line connects said receiver with atmosphere and asecond position in which the receiver is connected with said source; starting means in the upper portion of said receiver and actuatable by the sewage when the latter fills the receiver to a predetermined level for moving said control means into the second position whereby gas is introduced into the receiver and sewage closes said oneway valve means and is expelled into and through said pipe; time delay means operatively connected with said starting means and actuatable thereby when the control means is moved into said second position, said time delay means being further operatively connected with the control means for maintaining same in said second position for a fixed period of time; and means for moving the control means into said first position after the time delay means becomes deactivated, said last mentioned means being responsive to a predetermined minimum pressure in said receiver. 7

3. In a sewage ejector, in combination,. an ejector pot having an upper end and a bottom; an inlet pipe connected with said pot at the bottom thereof for introducing sewage by gravity flow therein; a one-way valve in said inlet pipe; a sewage evacuating pipe connected with said pot at its bottom and extending upwardly therefrom in substantially vertical direction; a source of compressed gas; a line communicating with said pot close to its upper end and connected with said source of compressed gas; control means including at least one valve in said line, said last named valve having a first position in which the line connects said pot with atmosphere and a second position in which the line introduces compressed gas from said source into the pot; starting means disposed in said pot in the proximity of the upper end thereof and actuatable by the sewagewhen the latter fills the pot to a predetermined level, said starting means being operatively connected with the control means in such a way as to move the last mentioned valve into said second position whereby to introduce compressed gas into the 'pot to expel the sewage through said evacuating pipe; a time delay means actuatable by the starting means and connected with the control means in such a way'as to maintain the last mentioned valve in said second position for a fixed period of time; and a pressure-responsive device connected with the pot and with the control means in such a way as to move the last mentioned valve into said first position after the time delay means becomes deactivated and the pressure in said pot drops to a predetermined minimum level.

4. A pneumatic pumping apparatus comprising, in combination, a receiver; conduit means for introducing a liquid into the receiver; an inlet trap in said conduit means adjacent to and below the level of said receiver; one-way valve means in the conduit means on the upstream side of said trap; piping in communication with said receiver at a lower portion thereof and extending upwardly therefrom; a source or" compressed gas; a line in communication with the receiver and adapted to be a ternately connected with atmosphere and with said source; control means operatively connected to saidline and having a first position in which the line is open to atmosphere and a second position in which the line introduces compressed gas into the receiver to close said oneway valve means and to expel the liquid through said piping; starting means actuatable by the liquid when the latter fills the receiver to a predetermined level for moving the control means into said second position; time delay means actuatable by said starting means for maintaining the control means in said second position for a fixed period of time; and means for moving the control means into said first position in response to a predetermined minimum pressure in the receiver after the time delay means becomes deactivated. Y 5. In a pumping device having a receiver, inlet piping forintroducing a liquid into the receiver, one-way valve means in said piping, and discharge piping connected to said receiver at a lower portion thereof and extending '13 upwardly from said receiver, in combination, a source of compressed gas; conduit means connecting the source with said receiver; valve means in said conduit means including a vent port and actuating means, said actuating means having a position of rest in which the receiver is closed to said source and open to atmosphere through said vent port, and a second position in which the conduit means permits flow of gas into the receiver and said vent port is closed; piping connected with said source and with the receiver and so disposed with. respect to said actuating means that gas under pressure therein moves the actuating means into said second position; second valve means in said piping for alternately closing the piping to said source and to said receiver, respectively; starting means in said receiveroperatively connected with the second valve-means for normally maintaining the latter in a first position in which the piping is closed to said source and adapted to' be actuated by a liquid in said receiver when the liquid-reaches a predetermined level in the latter whereby to move the second valve means into a second position -in which the latter closes the piping to said re- .ceiver; and time delay means for maintaining the second valve means'in said second position for a fixed period "of time."

6. ha pumping device having a receiver, an inlet pipe gas; afirst valve having a vent port, a diaphragm, and an actuating-member connected with said diaphragm, said actuating member having a position of rest and a second position; a first line for connecting the valve with said receiver; a second line for connecting the valve with said source, said second line being open to the first line when the actuating member is in its second position and the first line being open to said vent port when the actuating member is in position of rest; a second valve having a first port, a second port, a third port, and an actuating element extending into the receiver and having a first position in which the first port communicates with the second port and a second position in which the first port communicates with the third port; a first pipe for connecting the first port with said diaphragm; a second pipe for connecting the second port with said source; a third pipe for connecting the third port with said receiver; a float in the receiver attached to and normally maintaining the actuating element in its second position and adapted to be lifted by a liquid at a predetermined level for moving the actuating element into its first position; and a time delay operatively connected with the actuating element for retarding the movement thereof from its first into its second position, said pumping device operating in such a way that, when the actuating element is moved by the float into its first position, the gas from said source moves the diaphragm and the actuating member into the second position, gas is introduced into the receiver and expels the liquid through the outlet pipe, the time delay retarding the movement of the actuating element into the second position whereupon gas in the receiver maintains the actuating member in its second position until the liquid is evacuated from the receiver and the gas is free to escape through the outlet pipe to permit return of the actuating member into its position of rest.

7. The combination according to claim 6, wherein said second pipe communicates with said second line.

8. The combination according to claim 6, wherein said receiver is a pot having an upper end and a lower end, said inlet pipe and said outlet pipe being connected to the lower end of said pot, and said first line and said third pipe being. connected to the upper end of said pot.

1 1 '9. The combination according to claim 8, wherein said actuating element extends vertically downwardly into said pot and said float is a bell attached to the lower end of said actuating element.

10. The combination according to claim 6, wherein said 'inlet pipe defines an inlet trap adjacent to and below the level of said receiver, and said one-way valve means is on the upstream side of said trap.

11. The combination according to claim 6, wherein said outlet pipe extends substantially vertically from said receiver.

horizontal and having an upper end and a lower end; said inlet pipe, said first line and said third pipe being connected to said tubular element adjacent to the upper end thereof; said outlet pipe being connected to the lower end of said tubular element; and said actuating element is located in the proximity of'the upper end of said tubular element.

15. The combination according to claim 6, wherein said receiver comprises an elongated tubular element inclined from horizontal and having an upper end and a lower end, and a chamber having an upper end and a lower end with the latter in communication with the upper end of said tubular element, said inlet and said outlet pipe being connected to the upper and lower end ofsaid tubular element, respectively, said first line and said third pipe communicating with the upper end of said chamber, and said actuating element extending vertically into the upper end of said chamber.

16. The combination according to claim 6, wherein said actuating element is mounted for vertically reciprocating movements and said time delay comprises a stem rigidly fixed to said actuating element, a casing surrounding said stern and defining an enclosure, a liquid substance substantially filling said enclosure, and perforated means carried by said stem and so installed in said enclosure that the liquid substance retards movements of said stem in one direction and offers relatively little resistance to the movements of said stern in the other direction.

17. The combination according to claim 6, wherein said actuating element is mounted for vertically reciprocating movements and said second valve comprises a housing having an upper end through which said actuating element extends, said time delay comprising a casing defining an enclosure adjacent to and above said housing, a lower wall in said enclosure, a stem connected with said actuating element and reciprocable in said enclosure, said stem having an enlarged head at its upper end and defining a radial shoulder spaced from said head, a piston member 'disposedabout said stem and slidable between said head and said shoulder, said piston member having a peripheral Zone slightly spaced from said casing and at least one bore so disposed as to have one end closed by said lower wall when the piston member is. in lowermost position in said enclosure and another end closed by said head-when the piston member is in its uppermost position with respect to said stem, and a liquid substance substantially filling said enclosure.

18. The combination according to claim 17, further comprising a conduit in communication with said receiver and with the upper end of said enclosure.

19. The combination according to claim 18, wherein said last mentioned conduit is connected to said third pipe.

20. The combination according to claim 6, wherein said outlet pipe is vented above said receiver.

21. A pneumatic pumping apparatus comprising, in combination, a receiver; conduit means for connecting said receiver with a source of liquid; one-way valve means in said conduit means; discharge piping in communication with said receiver at a lower portion thereof and extending upwardly therefrom; a source of compressed gas; a line in communication with said receiver; control means in said line for alternately connecting same with said source and with atmosphere, respectively; electrical starting means operatively connected to said control means comprising a source of electric current and an electrode extending into said receiver, said starting means operating in such manner as to cause the control means to connect said line with the source of compressed gas when the electrode is contacted by a liquid in said receiver; electric time delay means connected with said electrode for maintaining for a fixed period of time said control means in a position in which the line is connected to said source; and pressure responsive means operatively connected with the receiver and with the control means and operating in such a way as to cause said control means to connect the line with atmosphere in response to a predetermined miniw'mum pressure in said receiver after said electric time delay means becomes deactivated.

22. A pneumatic pumping apparatus for use as a liquid ejector which comprises, in combination, a receiver; inlet piping for introducing a liquid into the receiver; one-way valve means in said piping; discharge piping in communication with said receiver at a lower portion thereof and extending upwardly therefrom; a source of compressed gas; a line in communication with the receiver; control means in said line for alternately connecting same with said source and with atmosphere, respectively; starting means operatively connected with said control means and comprising a source of electric current and electrode means extending into said receiver in such a way as to be contacted by the liquid therein when the liquid rises to a predetermined level to close the circuit of said electrode means and to cause said control means to permit flow of compressed gas into the receiver; electric time delay means comprising relay means in the circuit of said electrode means and a holding circuit for maintaining closed the circuit of said electrode means for a fixed period of time after the latter is contacted by the liquid in said receiver 'whereby the flow of gas into the receiver is continued; and pressure responsive means in the circuit of said electrode means and operatively connected with said receiver *for breaking the circuit of said electrode means in response to a predetermined minimum pressure in said receiver whereby said control means interrupts the fiow of compressed gas into the receiver and connects said line with atmosphere after said electric time delay means becomes deactivated.

23. A' pneumatic pumping apparatus for use as a liquid ejector which comprises, in combinatlon, a grounded receiver; inlet piping for introducing a liquid into the receiver; one-way valve means in said piping; discharge piping in communication with the receiver at a lower portion thereof and extending upwardly therefrom; a line in communication with the receiver; a compressor connected with said line; an electric motor connected to said compressor; an electrical source adapted to be connected to said electric motor; a check valve in said line; a first conduit communicating with said line intermediate said check valve and said receiver; a second conduit communicating with said line intermediate said compressor and said check valve; pressure responsive valve means between said first and said second conduit for closing the first conduit to atmosphere when compressed gas is introduced into said line and into said second conduit 'by said compressor, and for opening said first conduit to atmosphere when substantially atmospheric pressure prevails in said second conduit; an electric circuit for said compressor and said electric motor further comprising a starting electrode insulated from and extending into said receiver to be contacted by a liquid when the latter rises in the'receiver to a predetermined level, a source of electric current, electric time delay means including relaymeans, a holding circuit for maintaining said electric motor electrically connected with said corn pressor over said time delay means for a fixed period of time, and pressure responsive switch means operatively connected wi h said receiver, said apparatus operating in such a way that the liquid, upon contacting the electrode, closes a high resistance path between said electrode and said receiver to close said circuit and to actuate said time delay means and to connect said electric motor with said compressor, the compressor supplying gas under pressure through said line into the receiver and causing said pressure responsive valve means to close said first conduit to atmosphere, said time delay means maintaining the connection between the electric motor and the compressor for a fixed period of time whereupon said switch means breaks the circuit to stop said compressor in response to a predetermined minimum pressure in the receiver.

24. A pneumatic pumping apparatus for use as a liquid ejector which comprises, in combination, a grounded receiver; inlet piping for introducing a liquid into the receiver; one-way valve means in said piping; discharge piping in communication with the receiver at a lower portion thereof and extending upwardly therefrom; a line in communication with said receiver;a source of compressed gas connected to said line; a pilot valve connected to said line comprising an actuating member having a position of rest in which said pilot valve opens the line to atmosphere and closes the line to said source, and a second position in which the line communicates with said source and is closed to atmosphere; starting means for moving the actuating member into said second position, said starting means comprising an electrode insulated from and extending into the receiver to be'contacted by a liquid therein when the liquid rises to a predetermined level and closes a high resistance path between the electrode and the receiver; time delay means including relay means in the circuit of said electrode and energizable by said electrode when the latter is contacted by liquid in the receiver, said time delay means being connected with said starting means for maintaining the actuating member in said second position for a fixed period oftime; and pressure responsive switch means in the circuit of said starting means and operatively connected with said receiver for breaking the circuit of said starting means in response to a predetermined minimum pressure in the receiver whereupon the actuating member returns into said position of rest.

25. A liquid ejector comprising, in combination, a receiver; inlet piping for introducing a liquid into the receiver and comprising means for preventing the return flow of liquid therethrough; discharge piping for evacuating the liquid connected to said receiver at a lower portion thereof and extending upwardly therefrom; a source of compressed gas; a line for connecting the source with said receiver; starting means operatively con nected with the receiver and actuatable by the liquid therein when the latter rises to a given level, said starting means being further connected with said source for causing the flow of gas into the receiver in response to rise of liquid in the receiver to said level; time delay means operatively connected with said starting means and with said source for maintaining the flow of gas into the receiver for a fixed period of time after the liquid therein reaches said level; and means operatively connected with the receiver and with said source for interrupting the flow of gas into said receiver in response to a predetermined minimum pressure therein after said time delay means becomes deactivated.

References titted in the file of this patent UNITED STATES PATENTS 1,025,727 Wells May 7, 1912 1,157,491 Anderson Oct. 19, 1915 1,739,511 Kramer Dec. 17, 1929 (fisher references on following page) 17 UNITED STATES PATENTS Hatfield Nov. 26, 1940 Miller Oct. 7, 1941 De Witt Aug. 10, 1943 Elliot Dec. 17, 1946 5 Williamson Oct. 27, 1953 18 Stafford Feb. 23, 1954 Cibat-tari Dec. 6, 1955 Yeomans Jan. 17, 1956 Weis Dec. 24, 1957 Griffith June 30, 1959 Franey July 28, 1959

Claims (1)

1. A PNEUMATIC PUMPING APPARATUS COMPRISING, IN COMBINATION, A RECEIVER; CONDUIT MEANS CONNECTED TO SAID RECEIVER FOR INTRODUCING A LIQUID INTO SAID RECEIVER; ONE-WAY VALVE MEANS IN SAID CONDUIT MEANS; PIPING IN COMMUNICATION WITH SAID RECEIVER AT A LOWER PORTION THEREOF AND EXTENDING UPWARDLY THEREFROM; A SOURCE OF COMPRESSED GAS; A LINE IN COMMUNICATION WITH SAID RECEIVER AND ADAPTED TO BE ALTERNATELY CONNECTED WITH ATMOSPHERE AND WITH SAID SOURCE; CONTROL MEANS OPERATIVELY CONNECTED TO SAID LINE AND HAVING A FIRST POSITION IN WHICH SAID LINE IS OPEN TO ATMOSPHERE AND A SECOND POSITION IN WHICH SAID LINE INTRODUCES COMPRESSED GAS INTO THE RECEIVER TO CLOSE SAID ONE-WAY VALVE MEANS AND TO EXPEL THE LIQUID THROUGH SAID PIPING; STARTING MEANS ACTUATABLE BY THE LIQUID WHEN THE LATTER FILLS SAID RECEIVER TO A PREDETERMINED LEVEL CAUSING MOVEMENTS OF THE CONTROL MEANS INTO SAID SECOND POSITION; TIME DELAY MEANS OPERATIVELY CONNECTED WITH SAID STARTING MEANS FOR MAINTAINING THE CONTROL MEANS IN SAID SECOND POSITION FOR A FIXED PERIOD OF TIME; AND MEANS FOR MOVING SAID CONTROL MEANS INTO SAID FIRST POSITION IN RESPONSE TO A PREDETERMINED MINIMUM PRESSURE IN SAID RECEIVER AFTER SAID TIME DELAY MEANS BECOMES DEACTIVATED.

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