US3037669A

US3037669A - Pumping apparatus

Info

Publication number: US3037669A
Application number: US561413A
Authority: US
Inventors: Glenn A Patterson; Elmer M Deters
Original assignee: Red Jacket Manufacturing Co
Current assignee: Red Jacket Manufacturing Co
Priority date: 1956-01-26
Filing date: 1956-01-26
Publication date: 1962-06-05
Anticipated expiration: 1979-06-05

Description

June 5, 1962 G. A. PATT'ERSON ET AL 7,

PUMPING APPARATUS Filed Jan. 26, 1956 3 SheetS-Sheet 1 Md 7 w 9% 21am 7m m4 loc Zia/ MWM June 5, 1962 G. A. PATTERSON ET AL PUMPING APPARATUS 3 Sheet-Sheet'Z Filed Jan. 26, 1956 r l 3 Z 0 7 6 w 6 0, 9 S a 5 5 6 5666 i 5 5 5 6 i 5 RF L 2. am 4 M II U W l l lw w w l f Mm M r WIVV4\$\4\\\\\\\ w\ \WI s fl a 3 z 7 5 x 6% w w a m w a, FE w z 5 I A 7 Mn M Q 5 0 3 5 K g 7 Z .a 1 1.

June 5, 1962 e, A; PATTERSON ET AL 3,037,669

PUMPING APPARATUS 5 Sheets-Sheet 3 Filed Jan. 26, 1956 LEE! United States Patent 3,037,669 PUMPING APPARATUS Glenn A. Patterson and Elmer M. Deters, Davenport, Iowa, assignors to Red Jacket Manufacturing Co., Davenport, Iowa, a corporation of Iowa Filed Jan. 26, 1956, Ser. No. 561,413 14 Claims. (Cl. 222-63) This invention relates to pumping apparatus for dispensing gasoline or analogous liquids of high vapor pressure such as at filling stations and the like.

As the compression ratios of automobile engines has been increased, the fuel has also been improved to provide higher octane ratings. Incident to such improvement is the provision of more volatile gasoline. Because of the high vapor pressure, present installations where the liquid is elevated from the underground storage tank by suction pumps located in the dispensing pedestals are, in many cases, found to be inadequate since at higher altitudes or at warm summer temperatures there is excessive vaporization of the gasoline in the lines, and the pumps develop what is known as vapor lock.

An important object of the invention is the provision of an improved pumping apparatus for gasoline filling stations and the like which is free of vapor lock and embodies conventional pedestals and positive displacement dispensing pumps together with improved means for elevating the liquid from the underground storage tank to the inletsof the dispensing pumps.

Other important objects of the invention are the provision of an improved pumping apparatus for transferring gasoline or the like from the conventional underground storage tank of a filling station to the pedestals of a filling station; the provision of improved means for mounting a supply pump in association with the storage tank and the pedestals; and the provision of improved means for controlling the liquid pressure at the inlet side of the pedestal pumps.

Another object of the invention is the provision of a supply unit adapted for connecting existing dispensing stations to provide proper operation under modern conditions. 1

Other objects and advantages will appear from the following description and the accompanying drawings, in which:

FIGURE 1 is a fragmentary diagrammatic view showing the invention as embodied in a filling station;

FIGS. 2 and 3 together constitute a vertical section through a supply pump and its mounting showing the embodiment of FIGURE 1;

FIG. 4 is a fragmentary view on the line 4-4 of FIG. 2;

:FIGS. 5 and 6 are views similar to FIGS. 2 and 3 showing a further embodiment, and

FIG. 7 is a circuit diagram.

The present invention contemplates an apparatus such as shown diagrammatically in FIGURE 1 wherein the numeral 8 indicates a conventional underground storage tank buried beneath the pavement 9 of a filling station and having one or more pedestals 11 from which gasoline is dispensed through the usual hose 12 and valved nozzle 13 into the tank of an automobile in the usual fashion.

The pedestal 11 represents a dispensing unit such as now in common use made by a number of manufacturers and comprising the hose and

nozzle

12 and 13, a dispensing pump 14, ordinarily a positive displacement rotary pump, for drawing liquid from the storage tank and delivering it through the nozzle 13, air separating means 15 vented to atmosphere and metering and computing mechanism 16 all shown schematically in FIGURE 1.

The dispensing pump 14 has its inlet in communication 3,6315% Patented June 5, 1962 ice with the storage tank at a low level therein through a suction pipe or conduit means including a horizontal portion 17 connecting with the vertical portion 18 passing through the wall of the tank, a check valve, preferably an extractor type as shown, being interposed in the line to prevent return flow to the tank. A second suction line represented by vertical pipe 21, check valve 22 and horizontal line 23 leads to a second pedestal, not shown. In many filling station installations a number of such units are commonly connected with a single storage tank in this manner.

In the embodiment shown in FIGS. 1, 2 and 3 a supply pump and associated parts are mounted in the wall of the storage tank as by a flange 24 defining a threaded opening into the tank. Screwed into the flange is a pipe nipple 25 projecting upwardly. The upper end of the nipple is threaded into, and supports, an outlet distributor body or casting 26. The outlet casting has an upstanding cylindrical wall or flange 2,7 coaxial with the nipple 25 for the reception of the lower end of a casing 28 which extends upwardly to a point adjacent the surface of the ground or driveway. Seated in the driveway 9 is a thimble 29 surrounding the upper end of the casing and closed by a cover 31 flush with the driveway. The flange 27 carries an O-ring 32 on its inner surface cooperable. with the outer surface of the casing to seal the interface against the entrance of liquids. Cap screws 33 in the flange bear against the casing to secure the parts in assembled relation.

The outlet casting 26 has a central passage for the reception of a core member 36, an annular flange 35 on the core member bearing against an annular shoulder 34 to support the core member and the parts mounted thereon within the outlet casting. The flange is secured against the shoulder by a bayonet type joint including cap screws 37 and washers 38, a. ortion of the perimeter of which overlie the shoulder 34 in spaced relation for the reception of the flange 35 which has peripheral notches 39 allow iug the flange to move down onto the shoulder 34 past the washers and also has sloping surfaces 41 adapted to wedge the flange between the washer and the shoulder when the core is turned.

The outlet casting 26 also has an annular internal recess 42 defining part of a discharge chamber and is provided with tapped openings for the reception of

discharge conduits

43 and 44. The discharge casting also has internal

annular surfaces

45 and 46 adapted to snugly receive companion surfaces on the core 36, the interface being sealed by O-rings 47 and 48. The core 36 has a central chamber 49 forming part of the discharge chamber and communicating with the chamber'42 through a series of annular openings and also a lower tappedopening 51 communicating with passages St} for the reception of a delivery pipe 52 which extends downwardly from the core through the nipple 25 into the storage tank '8. Attached to the lower end of the delivery pipe 52- is a valve body 53, the lower end of pipe 52 being threaded into a collar 54 of the valve body. The valve body has an externally threaded sleeve 55 disposed downwardly which is threaded into an end member56. The end member 56 is attached by means of cap screws 57 spaced annularly thereof to the stator of a submersible electric motor '58. Attached to the lower end of the motor is a pump body 59, attached to the motor by annularly spaced cap screws 61. Extending between the pump body 59and the end member 56 is an annular shell 62 preferably of sheet metal disposed in spaced relation to the outer .periphery of the motor and sealed by means of O-rings 63 and forming, with the end member 56 and pump body 59, a motor housing. Disposed in the body 5% is'a pump impeller 64 mounted on the shaft 65 of the motor. The

pump body 59 has a depending internally threaded sleeve 66 within which is received a pipe nipple 67 which has mounted on its lower end a deflector member 68 secured thereon by cap screws 69. A conduit 71 for the electrical conductors necessary for the operation of the motor extends upwardly from the motor 58 through the delivery pipe 52 and through the upper wall of the core 36, this conduit preferably having a smooth outer wall for cooperation with an O-ring 72 interposed between the conduit and the upper wall of the core.

In normal operation the motor serves to drive the impeller 64 to move the liquid from the tank through conduit means to a point adjacent the inlet to the dispensing pump, the impeller drawing gasoline in through the side openings in the deflector plate 68, up through the nipple 67 and delivering the same through annular openings 73 into the space between the motor shell and the tube 62 to cool the motor, thence through annular openings 74 into the end member 56, the valve body 53, up through the delivery pipe 52 into the chamber 49 from which it passes out into the annular recess 42 to the

pipes

43 and 44.

The pipe 43 leading from the discharge head is, as shown in FIGURE 1, in communication with the

horizontal suction pipes

17 and 23 and is so connected by means of a T 75 connected into a cross member indicated at 76 Whereby to deliver gasoline to a point adjacent the suction side of the dispensing pumps in the pedestals. The pipe 44 likewise connects to additional pedestals in the same manner.

It will be noted that the connecting member 76 connects into the horizontal portions of the suction line between the check valves 19 and 22 and the corresponding dispensing pumps. In other words, the pipe 43 by-passes the check valves. Thus, the

pipes

43 and 44 deliver gasoline raised by the supply pump toward the inlet or suction side of the dispensing pumps 14. In order to prevent the dispensing pumps 14 from losing their prime by the return flow of gasoline back through the

pipes

43 or 44, suitable check valves indicated digrammatically at 77 are interposed in the system preferably in the inlet pipe to the dispensing pump of each of the pedestals as indicated in FIGURE 1 or between the dispensing pump and the venting means so that air cannot be drawn back into the dispensing pumps when the supply pump 58 stops or cannot be drawn back through the dispensing pump at one of the pedestals by action of the dispensing pump in another pedestal.

According to one phase of the invention, means are provided for controlling the pressure on the liquid in the suction pipe at a point in the region of the dispensing pump. For a number of reasons it is important that the gasoline be dispensed under the pressure of the dispensing pump and that there be little or no pressure applied to the liquid at the inlet side of the dispensing pump by action of the supply pump. To accomplish this purpose the invention contemplates a pressure relief valve interposed in the system between the impeller 64 and the inlet of the pumps 14, and further contemplates a novel form of such pressure relief valve forming a fluid level compensating device.

The valve body 53 has an annular rib 79 provided with upwardly disposed annular ports 81 communicating with the interior of the valve body, the body having annular faces 82 arranged to be engaged by an annular gasket or valve member 83 so as to cover the ends of the ports and close the same. The gasket 83 is carried on a fitting 84 upon which seats the lower end of a displacement member 85 in the form of a tube surrounding the delivery pipe 52 as best shown in FIG. 3. This displacement member extends upwardly to a point at or near the tank flange 24. In other words, it substantially spans the tank from the valve body 53 upwardly. The tube 85 is preferably formed of a material having a specific gravity near but slightly above that of the liquid being pumped, in this instance, gasoline. Certain of the synthetic resins which are impervious to gasoline and have a specific gravity in the region of 1.10 to 1.00 have been found to be suitable. The weight of the tube should be such as to gravitate downward to seat the gasket 83 when immersed in the gasoline in the tank. Obviously, an even lighter tube could be used if suitably weighted. The purpose of this valve and the displacement tube is to cause the supply pump to deliver liquid upwardly in the system to a given point, as for example, in the region of the inlet to the dispensing pump, at a fixed and uniform pressure; in other words, to maintain a column of liquid of uniform height regardless of the depth to which the supply pump is immersed in the liquid. It will be realized that as gasoline is pumped from the storage tank, the level of liquid in the tank drops. As it does so, more and more of the displacement tube 85 is uncovered which increases the weight applied to the seat 82 and consequently regulates the point at which the tube and gasket will be raised to permit liquid to flow back into the tank through the ports 81. The port sizes and the weight of the displacement tube are so proportioned as to compensate for this variation in the level of the liquid in the storage tank. No specific figures can be given because these will vary with the size and design of the installation, but they can be calculated from well known principles of physics.

Means are also provided for compensating for difierences in elevation between the supply pump and the dispensing pump in dilferent installations at the time of installation. To accomplish this, there is provided a plurality of collars indicated generally at 86 in FIG. 2, which are loosely disposed on the delivery pipe 52 and may conveniently be supplied by the manufacturer to the installer afiixed to the tube 52 by means of set screws 87. At the time of installation one or more of these collars may be loosened from the delivery pipe 52 and allowed to rest on the upper end of the displacement, tube 85 as indicated at 88 so that the weight of this collar or collars is applied or added to that of the displacement tube 85 so that the valve member 83 will open at a more elevated pressure in the system at the ports. Conveniently the weight of these collars may be adjusted to correspond to definite units of elevation, as for example, one foot. By this means the installer can measure the depth of the storage tank or make other suitable measurements and apply the required number of collars so as to cause the supply pump to deliver gasoline to a point adjacent the inlet of the dispensing pump.

The core 36 has an upstanding sleeve 89 having a bore 91 shaped for the reception of a pipe 92, the lower end of the pipe being threaded into the sleeve 89 at a point spaced from the upper end of the sleeve. Set screws 93 act between the sleeve and the pipe to lock the pipe into the sleeve and prevent its being unscrewed when the pipe is turned from above to effect assembly or disassembly of the unit at the bayonet connection. The upper end of the pipe 92 passes through a casing seal 94 of conventional construction which comprises an upper plate 95, a lower plate 96 and an outer annular gasket ring 97 and an inner gasket ring 98 so arranged that when bolts 99 are drawn up the gasket ring 97 is forced out against the inner wall of the casing 28 and the inner gasket ring 98 is forced inward against the side of the pipe 92 to effect a liquid tight seal. Secured to the upper end of the pipe 92 may conveniently be electrical fittings 101 and 102 for connecting a conduit 103 to the pipe 92 in liquid tight relation for the passage therethrough of electrical conductors 104 which pass through conduits 103, the fittings 102 and fittings 101, the pipe 92 and the conduit 71 to the motor 58.

Means are provided for disconnecting the motor from its source of power in the event that the level of liquid in the tank falls below the intake at the member 68. This is accomplished by utilizing the absence of liquid in the delivery pipe, discharge chamber and associated elements which are normally filled with liquid for the purpose of actuating a switch in the motor circuit. For this purpose there is provided, in this embodiment, a conventional pressure switch which may conveniently be mounted on the fitting 101 (FIGURE 1) connected to the chamber 49 by a pipe 100a so as to be operated responsive to the pressure in the chamber to open a circuit to the motor in the absence of liquid in the chamber, and the resultant pressure drop when the pump is no longer drawing liquid.

In FIGS. 5 and 6 there is a shown a modified form of supply pump construction wherein the motor is located outside the storage tank and acts to drive a pump positioned within the tank adjacent its lower side. This embodiment is most useful where the tank opening is too small for the passage therethrough of the motor structure. This embodiment likewise has the tank flange 24 attached to the tank 8 and a nipple 105' threaded therein.

Threaded or otherwise attached to the upper end of the nipple 10-5 is a distributor body or casing 106 defining a discharge chamber 107 having a plurality of laterally extending threaded openings for the reception of the discharge pipes 43 and 44' heretofore described. The chamber 107 in this instance forms a motor housing shaped for the reception of an electric motor 108 which in its details forms no part of the present invention. During pumping operations the liquid flows around the motor and acts to cool the same. The motor has a lower journal 109 mounted in a thrust bearing 111 and passing through a radial bearing 112. This form of the invention also has a core analogous to the core 36 of FIG. 2 but of slightly different construction and forms the end members .113 and 129 of the motor 108. The upper end member 113 is provided with an annular flange 114 similar in construction to that shown in FIG. 3 providing with the cap screws 115' and 116 a bayonet joint such as heretofore described. Below the flange 114- the end member has a cylindrical surface 117 complemental to an inner cylindrical surface 118' on the motor housing, the end member having a groove carrying an O-ring 119 cooperable with the surface 118 to seal the interface against the passage of liquid. The complemental surfaces 117 and 118 also provide a flame path suitable for the extinguishment of flame incident thereto. The flange 114 and its complemental shoulder on the motor housing serve to support the motor and associated parts on the motor housing. The end member 113 also carries a sleeve 121 adapted for the reception of a pipe 122 threaded therein and secured against rotation by cap screws 123. The pipe 122 extends upwardly through a casing 124- similar to the casing 28 mounted in an upstanding flange 125 on the motor housing, and sealed by an O-ring 126, the casing being secured in the flange by cap screws 127 as described in the previous form. The upper end of the casing 124 is sealed by a casing seal 128 identical with the casing seal construction shown in FIG. 2. Likewise the pipe 122 carries the same fittings at its upper end as shown in FIGURE 1.

The lower end member 129 carries the bearings 111' and 112 and is provided with depending struts 131 having an annular ring 132 at their lower ends. The ring 132 has cylindrical surfaces 133 complemental to cylindrical surface 134 on the inner side of the motor housing, an G-ring 135 sealing the interface against the passage of liquid. Threaded into the ring 135 is a depending delivery pipe 136 which extends down through the nipple 105 into the tank to a low point in the storage tank. A valve body 137 is threaded onto the lower end of the delivery pipe 136, the valve body having a central spider supporting a lower bearing138. As in the previous form, the valve body has an annular shoulder 139 providing space for upwardly extending spaced ports 141. Surrounding the body above the shoulder 139 is a disk holder 142 which carries an annular valve disk 143 adapted to seat over the ports 141. A displacement tube 144 simitory operation on modern fuels.

lar to the tube rests on the disk holder 142, the tube extending upwardly around the delivery pipe to a point adjacent the tank flange 24. Collars 145 are provided on the delivery pipe 36 to serve the same purpose as the collars 86 in the previous embodiment. The lower end of the valve body 137 is threaded for the reception of a. housing 146 of a centrifugal pump providing a chamber for a pump impeller 147 fixed to the end of a vertical shaft 148 which extends upwardly through the delivery pipe 136 and is secured to the motor shaft 109 by a coupling 14? whereby the motor acts to drive the impeller. One or more intermediate bearings such as the bearing 138 may suitably be employed for radial support of the shaft 148. The lower end of the pump housing 146 is threaded for the reception of a nipple or extension 1551 extending downwardly from the pump. A deflector 15.2 is secured to the lower end of the nipple 151, the deflector 152 serving a purpose identical with that of FIG. 3.

As in the previously described form a tube connects a channel 150a in the core to the pressure switch 100 so that the switch is operated in response to the drainage of liquid from the chamber.

While a number of different circuits may be used for the control of the pump motors, a circuit is diagrammatically shown in FIG. 7, by way of illustration, wherein the

numerals

161 and 162 indicate conventional 115-volt power lines. Located at each of the pedestals is a switch 163 which may be a double pole single throw switch having a switch blade 164 for closing a circuit to motor 165 in the pedestal 11 and driving the dispensing pump 14. A

second leaf 166 completes the circuit from power line 161 through

conductors

167 and 168 toa control box 169 which may be located at any convenient source above ground. The switch 163 is disposed in the pedestal 11 and adapted to be operated in the usual fashion when the nozzle 13 is hung up on the pedestal. Additional switches as indicated at 171 are mounted in each of the pedestals of the system and connected in parallel with the switch 163. The control box 169 may properly carry a starting capacitator 172, a motor starting relay 173 and an overload circuit breaker 174 connected to the motor of t the supply pump through the conductors 104-11, 104-11 and 104-c. Interposed in conductor 104-0 and connected to be responsive to the absence of liquid at a suitable point in the pressure system, in this instance to the pres-sure in the conduit means at the discharge chamber is a pressure switch 100 set to open the circuit of the motor when the pressure in the conduit means drops below a preselected point as will occur when the inlet to the pump is no longer submerged below the liquid level and the pump therefore begins to draw air into the system, allowing the pressure in the conduit means to fall below the setting of the pressure switch.

It will be apparent that the present invention provides many advantages, among them being a means by which present installations can be easily converted for satisfac- The structure provides what may be called a push-pull mode of operation, in which the supply pump picks up the liquid and delivers it to a point adjacent the inlet of the dispensing pumps but does not apply suflicient pressure to the liquid to move it into or beyond the dispensing pumps. As a result, the reduction in pressure applied to the liquid by the dispensing pump is very small and the tendency for vapor lock is practically eliminated. This is accomplished by providing a supply pump having a pumping capacity equal to or in excess of that required to supply all of the dispensing pumps in the system, incorporating in the conduit means a pressure loaded by-pass for by-passing the excess liquid back to the tank. The amount to be bypassed will, of course, depend upon a number of factors such as the number of dispensing pumps in use, and the amount of liquid being dispensed from the nozzles 13 which in certain instances will be closed when the dispensing pump is in operation. In some instances all of the capacity of the supply pump will be dispensed. This will also vary somewhat with the height of the liquid in the supply tank, and variations in this level are in the present instances largely compensated by the provision of the displacement tube 85. The tube extends from the by-pass valve to a point above the upper level when the tank is filled to its upper point. That portion of the tube below the liquid level displaces a volume of liquid equal to its own volume, and consequently reduces the effective weight if the tube on the valve by an equivalent weight of liquid. As the level falls more and more of the tube is uncovered and the weight on the valve is correspondingly increased, thereby causing the valve to open at pressures inversely proportional .to the level of the liquid in the tank to provide an approximately uniform pressure at some elevated point in the conduit means, preferably near the inlet of the lowest dispensing pump. The density of the tube and the port area are proportioned so that the valve will open by lifting the tube when the pressure on the liquid is atmospheric at a point slightly above the tank and below the elevation at which a pedestal is likely to be installed in a filling station. The

collars

86 or 145 facilitate installation of the supply pump and associated parts in an existing conventional construction.

Another advantage lies in the structure providing ease of installation and servicing of the supply pump and associated parts. It only becomes necessary, in an existing installation, to excavate to a level around the usual tank flange as at 24. Even in those cases where the tank has no such flange, one can be installed with minimum expense. Thereafter only the nipple 25, the distributor body 26 and the casing 28 in the first embodiment or the nipple 105, distributor body 106 and casing 124 in the second embodiment need be installed and connected to the

pipes

17 and 23 before the pit is filled and the thimble 29 installed in the driveway. Thereafter the pump, motor, delivery tube and parts attached thereto may be inserted as a unit and likewise may at any subsequent time be removed for servicing. For example, in the form shown in FIGS. 1, 2 and 3, the delivery pipe 52, the by-pass valve comprising body 53, gasket 83, displacement tube 85, the motor 58, the pump body 59 and the deflector member 68 are all secured together and to the core 36. The core is in turn supported in the distributor body 26 on the shoulder 34, secured in place by the bayonet connection. Therefore, all of these parts may be lowered through the casing 28 until the flange 35 rests on shoulder 34, thereby properly positioning the various elements in their proper relationship. Thereafter, by applying a wrench or other tool to the pipe 92, the entire assembly may be rotated to engage the bayonet connection and wedge the flange 35 under the washers 38. The assembly may be removed by reversing the steps. Cap screw 93 serves to prevent rotation of pipe 92 with respect to the core during this operation. The form shown in FIGS. and 6 is assembled in an analogous manner.

A further advantage lies in the fact that if necessary or desirable the installation can without further excavating, be converted to a pressure system by substituting a different assembly in the distributor body and eliminating the dispensing pumps.

Another feature of the invention is that the structure may be installed in the field by means of conventional tools even though the tank sizes and the depths may vary considerably. The

casing

28 or 124 is formed of conventional well casing, as for example, a 6" well casing, and requires no threading or other special treatment. Therefore, the installer need only cut a suitable length of casing and insert the lower end into the

flange

27 or 125. A suitbale seal is effected by the O-ring and the cap screws secure the casing in place. Likewise, to accornmodate the unit to different tank diameters, the

delivery pipe

52 or 136 together with associated parts is 8 factory assembled to a length suitable for minimum size conventional storage tanks and the

nipple

67 or 151 is provided so that the installer may insert at this point a nipple of suitable length to accommodate for tanks of larger diameter.

Another advantage is that the apparatus can, if desired, be arranged to utilize the essential elements of an existing system so that such systems may be converted at a minimum expense and without impairment of its capacity to function in the same manner as before. Accordingly, in the event that trouble should develop in the supply pump or its associated elements, the dispensing pumps 14 are operative to draw liquid from the tank through the

pipes

18 and 21, the check valves 19 and 22, and the

lines

17 and 23 in the same manner as in existing installations.

We claim:

1. The combination in a dispensing apparatus for gasoline and like liquids of a dispensing pedestal having a dispensing pump, a dispensing line connected to the outlet of the dispensing pump and having a manually operable dispensing valve therein, and a vented air separator means in the dispensing line, a storage tank located at a level below the dispensing pump, a conduit having an outlet connected with the inlet of the dispensing pump and an inlet at a low point in the storage tank for conducting liquid from the tank to the inlet of the dispensing pump, and means for delivering liquid through said conduit to the inlet of the dispensing pump to maintain a substantially constant, relatively low pressure thereat, with changing level of liquid in the supply tank, said liquid delivering means comprising, a supply pump located at a low point in the tank communicating with the conduit, for pumping liquid from the tank through the conduit toward the dispensing pump, a by-pass below the normal range of liquid level in the tank and between said conduit and the storage tank, on the outlet side of said supply pump for by-passing liquid from the conduit back to the storage tank, a valve in said by-pass operable to open position in response to pressure in said conduit, and means for applying a closing pressure to the valve in amount approximately inversely proportional to the liquid level in the tank to provide a relatively uniform pressure in said conduit on the down streamside of said valve sufiicient to F pressurize the liquid therein to a point near the inlet of the dispensing pump and insuflicient to force liquid out of the vent of the air separator means at the pedestal.

2. The combination in a dispensing apparatus for gasoline and like liquids of a dispensing pedestal, a storage tank located at a level below the pedestal, conduit means having an outlet connected with the pedestal and an inlet at a low point in the storage tank for conducting liquid from the tank to the pedestal, a supply pump located at the tank communicating with the conduit for pumping liquid from the tank through the conduit toward the pedestal, an electric motor for driving the supply pump located in said conduit for the passage of liquid around the motor for cooling the same, and means for disconnecting the motor from its source of power when the liquid level in the tank falls below the inlet to said conduit, comprising a pressure switch, and means for connecting the pressure switch with the conduit to interrupt the circuit to the motor in response to pressure drop.

3. The combination in a dispensing apparatus for gasoline and like liquids of a dispensing pedestal having a dispensing pump, a dispensing line communicating with the outlet of the dispensing pump and having a manually operable dispensing valve therein, a vented air separator communicating with said dispensing line, a storage tank located at a level below the dispensing pump, conduit means having an outlet connected with the inlet of the dispensing pump, the conduit having a first branch provided with an inlet at a low point in the storage tank for conducting liquid from the tank to the inlet of the dispensing pump under the influence of the dispensing pump, a check valve in said first branch to prevent return flow of liquid through said branch, said conduit means having a second branch provided with an inlet at a low point in the storage tank for conducting liquid from the tank to the inlet of the dispensing pump, a supply pump located at the tank communicating with said second branch for pumping liquid from the tank through said second branch toward the dispensing pump, and means for controlling the liquid pressure in the conduit to maintain a substantially constant approximately atmospheric pressure in the conduit at a point near the inlet to the dispensing pump with changing level of liquid in the supply tank comprising a by-pass between said second branch and the storage tank on the outlet side of said supply pump for lay-passing liquid from the second branch back to the storage tank, including a pressure loaded valve arranged to open when the pressure in said conduit means adjacent the inlet to the dispensing pump exceeds a set maximum to limit the pressure on the liquid in the conduit produced in response to operation of said supply pump to a pressure insufiicient to cause discharge of liquid through the vent of the air separator at the pedestal, and means for preventing return flow of liquid through said second branch.

4. The combination of claim 1 wherein the last mentioned means includes a displacement member having a density approximately that of the liquid being pumped disposed in said supply tank to be progressively uncovered by drop in the liquid level in the tank andmeans for applying the weight of the displacement member to the valve means to vary the loading in response to changes in the liquid level in the tank and thereby maintain approximately constant delivery pressure on the liquid in the conduit.

5. The combination of claim 1 wherein a part of said conduit extends vertically downward into the tank from an upper wall thereof, said supply pump is disposed near the lower end of said conduit part, said valve means comprises a port communicating between the conduit and the tank, and a closure member for the port and the last mentioned means comprises a tube surrounding the conduit part extending upwardly in the tank having its weight applied to the closure member to hold the same closed against the pressure in the conduit, the port, closure and tube being dimensioned and weighted for lifting of the closure to open the port and thereby maintain approximately uniform pressure in said conduit with change in liquid level in the tank,

6. The combination of claim 1 wherein the means for applying closing pressure to the by-pass valve comprises a displacement body having its weight applied to the valve and having a density approximately that of the liquid, positioned and shaped to be progressively uncovered by drop in liquid level in the tank to vary the loading in response to changes in the liquid level.

7. The combination in a dispensing apparatus for gasoline and like liquids of a dispensing pedestal having a dispensing pump, a storage tank located at a level below the dispensing pump, conduit means having an outlet connected with the inlet of a dispensing pump and an inlet at a low point in the storage tank for conducting liquid from the tank to the inlet of the dispensing pump, said conduit having a portion extending vertically downward in the tank, a supply pump disposed near the lower end of said vertical portion communicating with the conduit for pumping liquid from the tank through the conduit toward the dispensing pump, and means for controlling the liquid pressure in the conduit to maintain a substantially constant, approximately atmospheric pressure at the inlet to the dispensing pump, with changing level of liquid in the supply tank, comprising, a by-pass port between the conduit and the tank near the lower end of the conduit and above said supply pump, a closure member for the by-pass port, a tube surrounding the conduit portion extending upwardly in the tank, having its weight applied to the closure member to hold the same closed against pressure in the conduit, the port,

closure member, and tube being weighted for lifting of the closure to open the port by pressure of the liquid against the closure member, and a plurality of weights attached to the conduit above the tube, selectively releasable to rest upon the upper and of the tube, to preselect the conduit pressure required to lift said closure member.

8. In a pumping system for Volatile liquids, the combination of a storage tank for liquid, a first pump disposed at the tank and having its inlet disposed to withdraw liquid from the tank, a discharge conduit connected to receive liquid under pressure from said pump, a first electric motor connected to drive said pump, a number of liquid dispensers disposed at points remote from said first pump, each dispenser comprising a dispenser pump having a suction and a discharge port, an electric dispenser motor connected to drive the dispenser pump, a dispensing line connected to the discharge port and a manually operable valve in said line, a vented air separator means in each dispensing line, each dispenser pump having its suction port connected to said discharge conduit, electrical means for energizing the tank pump motor when any of the dispenser pump motors is energized, and means for controlling the pressure occurring at the suction ports of the dispenser pumps during operation of the tank pump to a pressure not substantially exceeding atmospheric pressure to prevent discharge of liquid through the vents of the air separator means at the liquid dispensers.

9. The combination of claim 8 wherein said means for controlling pressure includes a by-pass means communicating with said discharge conduit adjacent the outlet of said first pump and with said tank, a valve member for controlling flow through said by-pass, said valve member having weight means yieldably urging the valve member to a closed position with a force insuificient to maintain said substantially constant pressure at the suction ports of the dispenser pumps with changes in the rate of flow through said by-pass.

10. The combination of claim 9 wherein said weight means includes a plurality of separate weight elements adapted to be selectively applied to the valve member to increase the valve closing pressure in selected increments corresponding the additional pressure head required for preselected changes in elevation between the tank and the dispensing pump to adapt the pressure controlling means for different installations having different elevations between the tank and dispensing pump.

11. The combination of claim '8 wherein said means for controlling pressure includes a by-p-ass means communicating with said discharge conduit adjacent the outlet of said first pump and with said tank at a point substantially below the top of the tank, a valve member for controlling flow through said by-pass, and valve closing means in the tank connected to said valve member and responsive to changes in liquid level in said tank for applying valve closing force to said valve member correlative with the liquid level in the tank and sulficient to maintain said substantially constant pressure at the suction ports of the dispenser pumps with changes in liquid level in the tank.

12. The combination of claim 8 wherein said means for controlling pressure includes a valve casing in said discharge conduit substantially below the top of said tank and having ports therein for by-passing liquid from the discharge conduit back into the tank below the upper liquid level in the tank, a 'valve member for controlling flow through said ports, weight means engaging said valve member for yieldably urging said valve member toward its closed position, said weight means including a displacement member extending upwardly from said valve member to a point adjacent the top of the tank to displace a volume of liquid correlative with the liquid level in the tank whereby to reduce the valve closing pressure on said valve member in proportion to the height of the liquid level in the tank above said valve member.

13. A dispensing system for gasoline and like liquids comprising at least one dispensing pedestal; said pedestal including a dispensing pump having an inlet and an outlet, a dispensing line connected to the outlet of the dispensing pump, a manually operable valve in the dispensting line, and a vented air separator means in the dispensing line; a remote storage tank located at a level below the dispensing pedestal, means for delivering liquid from the tank to the outlet of the dispensing pump and for maintaining a substantially constant pressure at the inlet of the dispensing pump with changing level of liquid in the tank, which substantially constant pressure is sufiiciently low to prevent discharge of liquid through the vent of the air separator means; said liquid delivering means including a supply pump having an inlet located at a low point in the tank and an outlet, conduit means connecting the outlet of the supply pump to the inlet of the dispensing pump in the pedestal, pressure regulating valve means in the conduit means for regulating the liquid pressure in the conduit means, and means in the tank connected to the pressure regulating valve means and responsive to changes in the liquid level in the tank for operating the regulating valve means to maintain said substantially constant pressure in the conduit means adjacent the inlet of said dispensing pump with variation in level in said tank.

14. A dispensing system for gasoline and like liquids comprising; a plurality of dispensing pedestals; said dispensing pedestals each including a dispensing pump having an inlet and an outlet, a dispensing line connected to the outlet of each dispensing pump, a manually operable dispensing valve in each dispensing line, and a vented air separator means in each dispensing line; a remote storage tank located at a level below the dispensing pedestals; means for delivering liquid from the tank to the inlets of the dispensing pumps and for maintaining a uniform substantially atmospheric pressure at the inlets of the several dispensing pumps to prevent discharge of liquid through the vents of the air separator means at the dispensing pedestals; said liquid delivering means including a supply pump having an inlet located at a low point in the tank and an outlet, conduit means connected to the outlet of said supply pump and having branches connected to the inlets of the dispensing pumps at the several pedestals, valve means in said conduit means at said tank, and means operative on the valve means to maintain said uniform substantially atmospheric pressure on the liquid adjacent the inlet of said dispensing pumps with variations in the liquid level in the tank.

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