US2569554A - Fluid dispensing system - Google Patents

Description

Oct 2 1951 D. D. BuTToLPH FLUID ISPENsING SYSTEM 2 Sheets-Sheet 1 Fiied Dec. 1e. 1949 STORAGE STORAGE TANK TANK

HYDRAULIC FLUID STORAGE INVENTUR. D D BUTTOLPH WMS? ATTORNEYS Oct. 2, 1951 D. D. BuTToLPH 2,569,554

FLUID DISPENSING SYSTEM Filed Dec. 16. 1949 2 Sheets-Sheet 2 BY OPEN /nf 9M' A7 'rop/vers m RM 75W mm W NT WT U mf ma. D M 3 o ak k M/A 5 5 m 7 Cl 6 6 O 6 f H 1mm 6 L 3%, 6 l.. A 2 f La w. 4 R 2 UE El fl R2 EW, UF- RR QSHW PO EW F R A WO PW LE HF om m0 TS HE D ma clfosco Patented Oct. 2, 1951 Doyle n. Buitolpll, Bartlesville, Okla., assigner to Phillips Petroleum :Company, a corporation of Delaware Application December 16, 1949, Serial No. 133,264

12 Claims. (Cl. 62-1) This invention relates to apparatus for controlling flow offluids. In one embodiment this invention relates to a system for dispensing liquefied gases. In another embodiment this invention relates to a system by means of which an uncontrolledvflow of liquefied gas from a storage tank can be terminated automatically, thereby enhancing the safety of handling such liquids.

From the stand-point of safety it is essential that all connections to liqueed petroleum gas containers be protected as much as possible from the results of mechanical damage. Under a few special circumstances it is entirely possible to assemble various tank outlets with their valves and fittings into a relatively small area and to protect the assembly with a heavy guard. However, on most mobile equipment it is necessary to have pipe lines located in areas which will be vulnerable. to breakage through collision. It has been the practice to use excess flow valves to protect liquefied petroleum gas containers against loss of contents through outlet connections in case of pipe breakage. The excess flow valves are generally installed in the tank outlet nozzles.

Such a valve is held in a normally open position by means of a spring, and the valve closes automatically when a ow occurs greater than that for which the valve is designed. While the excess flow valve is a reliable safety device under most conditions, there are instances where it cannot perform its desired function. For example, if an excess ow valve is designed to pass 100 gallons per minute and a line break on the down stream side of the valve is such that the break will pass only '15 gallons per minute, the excess flow valve will not close. Obviously, the escape of an inflammable liquid, as liquid propane or butane at such a rate would create a tremendous hazard.

My invention is concerned with a control system in combination with a storage tank containing a fluid under superaltmospheric pressure, providing for the emergency shut-olf of liquid flow from the storage tank, in the case of line breakage in the dispensing system, or the occurrence of re in close proximity to the system.

An objectof my invention is to provide a system for dispensing gas under pressure.

Another object of my invention is `to provide safe equipment for handling liqueed gases, that will be safe as can be devised, and that will comply with the Standards of the National Board of Fire Underwriters and the NBFU pamphlet No. 58, and all similar standards of safety.

Another object is to provide a system for handling liqueed gases.

Another object is to provide, in combination with a storage tank containing liquefied gases at superatmospheric pressure, a safe system for dispensing liquid from the tank.

Another object is toprovide for the automatic shut-oil of liqueedgas flow from a storage tank, in the event of the occurrence of re in close proximity to the flow system. Y

Another object is to provide for the automatic shut-off of liquefied gasow from a storage tank, when such liquid is being dispensed therefrom or delivered thereinto, in the event of a break or rupture of a conduit carrying such liquid.

Other objects will be apparent to those skilled in the art from the accompanying discussion and disclosure. v

In accordance with my invention I have provided a systeniin combination with a storage tank containing a fluid under superatmospheric pressure, for dispensing the fluid lfrom the tank and automatically terminating fluid flow therefrom, in the event of line breakage in the dispensing system, or the occurrence of re in close proximity to the tank and dispensing system.

In a broad embodilnent, the dispensing system of my invention, in combination with the tank, comprises a dispensing line in communication with the tank, a pressure iluid conduit for conducting uid flow under pressure, means for establishing fluid pressure in the'conduit, a first motor valve in the liquid dispensing line, comprising a shut-off valve controlling flow of liquid from the tank, a motor controlling the valve, and

means biasing the valve closed. The motor of the rst motor valve is connected to the fluid pressure conduit and is operated by uid pressure therein to overcome the biasing means and to open the valve. Means is employed for effecting a pressure diierential between a rst and second point in the liquid dispensing line. A second motor valve is employed, the motor of which is connected to the dispensing line at the rst and second points above cescribed, and operated by the pressure differential across these two points when that pressure differential exceeds a predetermined value. The valve of the second motor valve is connected to the pressure fluid conduit at a point between the fluid pressure establishing means and the motor of the rst motor valve, and bleeds the pressure uid conduit of uid pressure when operated by the motor of the second motor valve, whereby the biasing means above discussed, closes the rst motor valve and stops ow through the dispensing line when the pressure conduit in parallel to each other.

In a preferred embodiment the valve of the first motor valve is disposed inside the tank, and

the dispensing line and fluid pressure conduit.

points in the wall of the fluid pressure conduit.

The second motor valve is preferably a. diaphragm motor controlled valve and can be supplemented with means for causing additional hysteresis to regulate its rate of closing to permit fluid pressure to be completely bled from the pressure conduit so as to insure that the biasing means will completely close the valve in the dispensing line. and thereby terminate flow from the tank.

The dispensing system of my invention is superior from a safety standpoint to the excess flow valve previously discussed above, because the valve in the f'lrst motor valve, i. e. the shut-off valve, is in a normally closed position except when fluid is being pumped into or out of the tank, so that except when flow is occurring, the tank is protected at all times by means of a closed shut-off valve. When liquid is being passed through the dispensing line, the system of my invention provides for automatically bleeding, or venting, fluid from the pressure uid conduit in case of fire in close proximity to the system or in case of line breakage above discussed, whereby in either instance or both, the valve in the liquid dispensing line is closed and the flow of liquid from the tank is terminated. Fusible plugs employed in the pressure conduit wall can be fabricated of such low melting materials as Woods metal, or bismuth solder, or other such suitable fusible alloys having a melting point lower than that of the materials of which the pressure conduit is fabricated. Generally, fusible plugs are selected having melting points not lower than about 80 C., and not exceeding about 20D-300 C., although plugs having melting points outside that range may be utilized if desired. In case of re in close proximity to the dispensing system, the fusible plugs in the fluid pressure conduit become heated, and melt, providing openings in the wall of the fluid pressure conduit through which uid under pressure immediately escapes, thus permitting the tank shut-off valve to close.

I prefer to locate the fluid pressure conduit and the gas dispensing line in close proximity to each other. in order that any breakage that occurs in one line will be very likely to occur in the other, so that the combined features of my invention will be employed concomitantly, to terminate flow of liquid from the tank. For these reasons I prefer to dispose the liquid dispensing line and fluid It is to be understood however that my invention provides for terminating the flow of liquid from the storage tank when either the pressure fluid conduit or the liquid dispensing line is broken, regardless of whether or not they are in close proximity to each other.

For a better understanding of my invention, reference is made to the attached gures illustrating various embodiments of my invention. It is to be understood that Figures 1 to 5 are diagrammatic only and may be altered in many respects by those skilled in the art and yet remain within the intended scope of my invention. Figure 6 is a graphic illustration of hysteresis of a diaphragm controlled valve employed in the practice of my invention. and discussed more fully hereafter.

Figure 1 is a diagrammatic elevational viev1 of a plurality of storage tanks in combination with a liquid dispensing system embodying one form of my invention. In Figure 1 is illustrated the use of an orifice in the liquefled gas dispensing line, and a diaphragm motor valve responsive t0 pressure drop across the orifice, i. e. it vents hydraulic fluid from the fluid pressure conduit in response to excessive liquid flow through the opened shut-off valve. It is t0 be understood that a single storage tank or a plurality, may be employed in conjunction with the dispensing system, as desired.

Figure 2 is a sectional elevational view of a. motor valve, operated by fluid pressure in the uid pressure conduit, above discussed, that can be employed in the practice of my invention to permit flow of liquid to and from the storage tank.

Figure 3 is a diagrammatic elevational view, with parts broken away, of one embodiment of apparatus by means of which the diaphragm controlled valve of Figure l can be operated to vent fluid pressure from the uid pressure conduit. In the embodiment of Figure 3 the diaphragm controlled motor valve is opened in response to pressure differential across the liquefied gas flowline, when it exceeds a predetermined value, and the valve remains permanently open, until manually closed.

Figure 4 is a diagrammatic elevational view with parts broken away of another embodiment, differing from that of Figure 3, by means of which the fluid pressure can be vented from the pressure fluid conduit. In this embodiment a check valve in combination with an orifice is employed, each on the high pressure side and the low pressure side of the diaphragm, whereby a desired hysteresis effect is provided so as to cause the diaphragm control valve to slowly close, so that ample time is provided for venting the necessary amount of hydraulic fluid.

Figure 5 is a sectional view of another embodiment of a diaphragm controlled valve that can be employed to vent fluid pressure from the fluid pressure conduit. This embodiment provides still a further modification in the design of the diaphragm controlled valve already discussed in Figures 3 and 4, and employs a piston and chamber in conjunction with a single check valve and an orifice, to provide a hysteresis effect to permit the valve to close slowly so as to permit the necessary amount of fiuid to be vented from the fluid pressure conduit.

With reference to Figure 1, storage tank I0 is provided for storing liquefied gaseous hydrocarbons Il and such vapors as may be present. A liquid dispensing line I3 is connected with tank I0 in communication with liquid therein. Conduit I4 is a pressure fluid conduit, and fluid pump I6, is connected to one end of conduit I4, to withdraw fluid from storage I1 through line I5 and to deliver same under pressure into conduit I4.

A motor valve I2 comprises an outlet shut-off valve ZIJ (see Figure 2) in liquid dispensing line I3, preferably disposed inside tank I0, and a fluid operated motor 25 (see Figure 2) biasing the valve 20 closed. Motor 25 is connected to conduit I4 and operated by uid pressure therein to overcome the biasing effect of the motor and to move valve 20 into an open position. Orifice 2| is located in gas dispensing line I3, preferably at a point outside tank IIJ and often in close proximity to motor I2. Orifice 2l is located in line I3 to constrict the flow of liquid therethrough so as to develop a pressure differential therein commensurate with a desired rate of liquid ow from tank II) through line I3. Conduit I4 is equipped with fusible plugs 22. Check valve I8 is located in conduit I4 at a point in close proximity to the discharge side of pump I5 to insure constant pressure of iiuid therein, i. e. to prevent iiuid in line I3 from backing toward pump I6. operations.

A second motor valve comprises a diaphragm controlled motor 23, connected on one side of the diaphragm by connecting line 24 to dispensing line I3 at a point on the high pressure side of orice 2|, and connected through line 26 on the other side of the diaphragm to line I3 at a point on the low pressure side of orifice 2l. Normally closed valve 30 of the second motor valve is connected with pressure iiuid conduit I4 through connecting line 35 at a point intermediate pump IIi and motor 25 of motor valve I2. Diaphragm motor 23 is responsive to pressure differential across orice 2| when that difierential exceeds a predetermined value, at which time it causes valve 30 to move into an open position.

during normal dispensing" In the operation of the embodiment illustrated in Figure l, hydraulic iiuid is withdrawn from storage II through line I5 into the low pressure side of pump I6, and discharged therefrom into conduit I4 to develop a hydraulic iiuid pressure therein such as from -20 p. s. i. g. to as high as 300 p. s. i. g., depending on the pressure exerted by iiuid in the tank. Fluid under pressure in conduit I4 is passed to motor 25 of motor valve I2, causing the motor to move shut-off valve into an open position, permitting thereby a iiow of liquid from tank I0 through line I3 and orifice 2I. across orice 2| is commensurate with the normal rate of liquid iiow from tank III through liney I3. Normal rate of liquid flow from tank III can be any desired value, often from 'I5-300 gallons per minute. It is an abnormal flow, by which I mean liquid iiow from tank III through line I3 at a rate higher than the normal rate, with which my invention is concerned. Ordinarily, such abnormal flow results from a breakage in line I3 thereby causing liquid to escapey from the system and to constitute a serious lire hazard. In the event that such a break occurs, it is of course desirable to terminate the ow oi' liquid II from tank III, and this is done by bleeding, or venting, iiuid from conduit I4, thereby relieving iiuid pressure on motor and permitting spring 36 to close valve 20. Bleeding of iiuid from conduit I4 is done by means of diaphragm motor 23 operating normally closed valve 30. Motor 23 is responsive to pressure differential across orifice 2| when it exceeds the value predetermined as being commensurate with normal liquid iiow from tank I0 through line I3, and when so responding, operates valve to move it into an open position. When valve 30 is opened by diaphragm motor 23, iiuid is vented from chamber 34 through line I4, line 35, valve 30, discharged through line 3 I, and returned to storage Il, or when desired, discharged directly through lines 3| and 3Ib to the atmosphere. When it is desired to manually terminate normal ow of liquid from tank I0, iluid under pressure inline I4, can be withdrawn therefrom and returned to storage I'I, through line 9, thereby permitting motor valve 25 to bias valve 20 closed.

Fusible plugs 22 are disposed preferably at a plurality of points in conduit I4, so that in the The normal pressure differentialcase of occurrence oi' nre in close proximity to the liquid iiow system, these plugs become heated and melt, providing thereby openings in the side wall of conduit I4 through which iluid under pressure therein can escape, whereby uld is vented from chamber 34, permitting spring 36 to close valve 20, terminating flow of liquid from tank I0. As stated hereinbefore I prefer to utilize conduit I4 and line I3 preferably disposed in parallel. In a preferred form of one such embodiment. a iiexible fluid pressure conduit I4 is disposed in close parallel relation to a iiexible dispensing line I3 along the entire length of line I3.` This is particularly advantageous when dispensing liquid from a mobile unit to a liquid storage, as for example a storagev tank in a domestic heating system.

vI'he iiow system of my invention offers particular advantages in the operation of mobile units for the reason that in such cases it may happen that during the time the liquefied petroleum gas is -being dispensed from, or being charged into tank I0, the dispensing unit is damaged by collision therewith of a passing vehicle, or by interference from sources uncontrolled by the operator of the unit. Any line breakage during dispensing operation is serious for the reason that it endangers the surrounding area by discharging inflammable materials thereinto. When that happens the ow of liquid from tank I0 is abnormally high and valve 3l) is im mediately moved into an open position by dia-7 phragm motor 23, whereby iluid is vented from. line I4 and shut-oi valve 20 is closed. Similarly' when for any reason conduit I4 is broken, fluid, pressure is vented therefrom, permitting valve: 20 to close.

If desired to operate the system of Figure 1 without the feature of maintaining line I3 in. close proximity to, and in parallel with conduit I4, that can be done by closing valve I5. With reference to Figure 2, illustrative of a motor valve I2 of Figure 1, motor valve I2 is comprised of valve disk 39, held in place by disk retainer 32 and cap member 33 against valve seat 35. The valve 20 as illustrated is in a closed position and is biased-closed by means of coil spring 36 supported from points 4I) on the exterior wall of the top portion of piston chamber 34. Disk. retainer 32 is held in place by screws 38. Valve disk 39 is raised fromseat 35 by raising cap member 33 in an upward direction against the force of spring 5. This is done by means of fluid pressure exerted upwardly against the interior of cap 33, by hydraulic fluid introduced under pressure through conduit 45 against the bottom of piston 4I. Piston 4I is disposed vertically inside piston chamber 34 and is held in alignment by piston rings 42 separated by an O ring 43. In response to pressure of hydraulic iiuid thus introduced, piston 4I is raised upwardly against the top portion of cap member 33, raising it vertically. When this occurs, the extent to which the valve is opened is dependent upon iiuid pressure. which in turn is regulated to permit the desired rate of flow of liquid, to be passed through valve 20. Liquid passed through valve 20 is discharged through opening 44.

Suitable arrangements can be employed such as ring 45 welded to the outside of tank III to which the main body of motor valve I2 can be secured by means of studs 47. Screen 48 is disposed to prevent contact of foreign lmaterials such as tank sedimentamill scale, and the like,

within tank I0, with valve disk 39 and valve seat 35, thereby preventing any possible damage to these members of motor valve I2.

As illustrated in Figure 2, motor valve I2 is opened and closed by regulating the pressure of hydraulic uid in line I4. Accordingly, motor valve I2 can be used during dispensing and charging operations since it can be operated to permit liquid flow through line I3 in either direction.

With reference to Figure 3, an orifice 2I is omitted and instead a pressure differential commensurate with normal rate of liquid flow in line I3, is developed by selection of line I3 of length and size to provide an inherent pressure differential in liquid fiow therethrough, commensurate with the desired flow rate fromtank I through line I3. As illustrated in Figure 3 diaphragm motor 23 is connected on its high pressure side by connecting conduit 24 with line I3 at a point on the high pressure side of the pressure differential therein, and is connected on its low pressure side with line I3 at a point on the low pressure side of the differential therein. In this embodiment, when pressure differential in line I3 exceeds a predetermined value, valve 33 is moved by diaphragm motor 23 into an open position, thereby venting fiuid from conduit I4, and permitting motor valve I2 to close and terminate flow of liquid from tank I0.

As an added feature of my invention I have provided a means for holding valve 30 in an open position until manually closed. This is done by means of catch 52 driven by spring 53 to engage ring 54 on valve stem 5I, when stem 5I is moved in a downward direction to unseat valve 30. This feature of my invention provides for the complete venting of hydraulic fluid pressure from conduit I4 to assure complete closure of motor valve I2 to terminate flow of liquid from tank I3. Obviously, if valve 30 were adapted to be raised to an open position by motor 23, member 52 and ring 54- would be altered by one skilled in the art, to cause valve 33 when open, to be held in the open position until manually closed.

With reference to Figure 4, another embodiment of my invention is illustrated by means of which diaphragm motor 23 causes valve 30 to open in response t0 a pressure differential across orifice 2| when that differential is higher than a predetermined value. In this embodiment, pressure taps 1I and 12 are disposed on the high pressure and low pressure sides of orifice 2I respectively. Conduit 24 connects .the high pressure side of diaphragm motor 23 with the high pressure side of orifice 2| in line I3 and contains check Valve 13. Similarly, conduit 26 containing check valve 14 is engaged with pressure tap 12 at one end, and is connected at the other end with the low pressure side of diaphragm motor 23. When an excessive pressure drop is developed across orifices 2l, valve 30 is caused to move into an open position as already discussed. However, in some instances a suiiicient amount of fluid may not have been vented from conduit I4 to permit motor valve I2 to be completely closed at the time that the pressure differential across orifice 2| has been lowered to a value commensurate with the normal flow rate. In such a case, the flow of liquid from tank Il is not terminated, and the uncontrolled escape of liquid from conduit I3 must still be reckoned with. In this embodiment such insufficient venting is prevented by means of orifice 16 in by-pass line 11 disposed around check valve 13, and orifice 18 in line 19 installed as a by-pass around check valve 14. Check valve 13 permits one-way fluid flow in a direction from tap 1I toward diaphragm motor 23, and check valve 14 permits one-way flow of fluid through line 26 toward tap 12. After diaphragm motor 23 in response to excessive pressure differential across orifice 2i has caused valve 30 to open, and when a normal differential is developed across orifice I3, check valve 13 prevents the escape of any fluid from diaphragm 23 through line 24, and instead, fluid passes into line 11 through orifice 16 at a retarded rate. Similarly, fluid entering the low pressure side of diaphragm motor 23 in response to a lowered pressure differential across orifice 2 I, must enter at a retarded rate through orifice 18, accordingly, the rate at which valve 30 is permitted to close is thereby lessened, whereby the necessary amount of fluid is vented from conduit I4 before valve 30 can be closed.

Although I have illustrated the use of the combination in line 24 of check valve 13, by-pass line 11 and orifice 16, together with the combination in line 25 of check valve 14, by-pass line 19 and orifice 18, it is to be understood that, if desired, only one of such combinations need be utilized in providing the desired hysteresis effect on motor 23. Thus, in operating the embodiment of Figure 4, valve 8| in by-pass line 62 can be opened, when valve 83 in by-pass line 8'4 is closed, or valve 83 can be open when valve 8| is closed.

In Figure 5, I have illustrated still another embodiment of my invention whereby, after valve 3l) has been moved into an open position by motor 23 and then permitted to close, it can close at a retarded rate to permit complete venting of fluid pressure from conduit I4. With reference to Figure 5, piston chamber, closed at one end and open at the other, is connected at its open end with the low pressure side of diaphragm motor 23. Piston 63, supported pressure tight in chamber 65 by ring 60, is connected to the diaphragm 10 of diaphragm motor 23, and is urged in a direction toward the diaphragm 10 by coil spring 64, disposed in that portion of chamber 65 intermediate its closed end and the piston.

Conduit 15 extends through piston 63 to connect that portion of chamber 65 intermediate its closed end and the piston, with the low pressure side of diaphragm motor 23. Check valve 66 is disposed in conduit 15 at a point on the diaphragm side of the piston and permits one-way fluid flow through conduit 15 in a direction toward diaphragm 10.

A suitable means for permitting restricted fluid flow into chamber 65 from the diaphragm side of piston 63 is employed, as for example, an orificed passageway through piston 63, or a check valve 65 adapted to permit a predetermined amount of leakage. Such means specifically illustrated. is conduit 68 connecting the portion of chamber 65 intermediate its closed end and piston 63, with the diaphragm side of piston 63, and orifice 61, in conduit 68. Operating in accordance with the embodiment of Figure 5, valve 30, having been moved into an open position by motor 23 and then being permitted to close, is closed at a retarded rate, by virtue of orifice 61 in line 68, which permits only a slow return of fluid from the low pressure side of orifice 2| to the spring side of piston 63, whereby the reseating of valve 30 is delayed, and line I4 is sufficiently bled of fluid pressure.

Obviously, the embodiment of Figure 5, is not limited to operation with an orifice 2 I, but can be applied in conjunction with any means for effect- ,y 9 ing a pressure differential responsive to liquid flow, from tank I through line I3.

The embodiments illustrated in Figures 3, 4 and 5 with respect to diaphragm motor 23 and valve 30 clearly demonstrate means by which a desired hysteresis effect can be imposed on the diaphragm motor controlled valve so as to assure complete venting or bleeding of fluid pressure from fluid pressure conduit I4 delivering uid to motor valve I2. However, in various instances dependent upon the specific equipment at hand, the inherent hysteresis in the valve assembly employed will prevent any unduly quick closing action of diaphragm motor 23 on valve 30. This effect is more clearly illustrated in Figure 6 which shows graphically the relation of pressure differential to operation of a diaphragm controlled motor valve, and further illustrating that a lower differential can be utilized in holding the valve open than is required to initially move it to that open position. In other words, the friction that results between the valve stern and packing for example, inherently retards the closing of the valve to an extent that in most instances wherein a diaphragm controlled motor valve is employed, fluid pressure will be permitted to be completely relieved from conduit I4 before valve 30 is permitted to close, making it unnecessary for any means of the type illustrated for imposing an additional hysteresis effect on the diaphragm controlled motor valve.

In the discussion hereinabove with respect to the location of motor valve I2, I have stated that Vit is preferred to locate the valve of that assembly `inside tank Ill. This is preferable for the reason that, in that position, it is less vulnerable to the effect of mechanical damage, providing thereby a greater safety factor in 'the operation of the control system of this invention.

Although it is not a preferred feature of my invention, if desired, line I3 can be extended into tank l0 and the valve of motor-valve I2 can be disposed in line I3 in tank IU at any desired point.

It is to be understood that although in Figure l I have illustrated the liquid dispensing line i3 and fluid pressure conduit Ill disposed in parallel relation to the other, it is a feature of my invention that liquid iiow from tank IIJ will be terminated when breakage occurs in either line I3 or conduit I4, or both, regardless of whether or not they are in parallel.

Although with reference to the drawings I have presented a preferred embodiment of my invention as applied to dispensing a liquefied gas under superatmospheric pressure, it is to be understood that my invention more broadly provides for dispensing fluids of any type under pressure, such as a normally gaseous hydrocarbon, ammonia, or the like, either in gaseous or liquid state.

As will be vevident to 'those skilled in the art, various modifications of this invention canbe made, or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

I claim:

1. A liquefied gas dispensing system, comprising in combination, a tank, a liquid dispensing line in communication with said tank, a pressure fluid conduit, means to establish fluid pressure in said conduit, a first motor valve comprising a valve in said line controlling flow of liquid from said tank, a motor controlling said valve l0 and means biasing said valve closed, said motor being connected to said conduit and operated by fluid pressure therein to overcome said biasing means and open said valve, means for effecting a pressure differential between a first and second /point in said line responsive to liquid flow therein, a second motor valve comprising a motor co'nnected to said line at said points and operated by `said pressure differential when it exceeds a predetermined value and a valve connected to said conduit between saidfluid pressure establishing means and the motor cf said first motor valve bleeding said conduit of fluid pressure when operated by said motor of said second motor valve, whereby said biasing means closes said valve in said line and stops liquid flow in said line when said differential exceeds said predetermined value.

2. The apparatus of claim 1 wherein said liquid dispensing line and said pressure fluid conduit are disposed parallel and adjacent to each other.

3. The apparatus of claim 1 wherein said means for effecting a pressure differential in said liquid dispensing line, is said line of a predetermined length and size through which pressure differential inherent in the iiow of liquid therethrough is' said pressure differential.

4. The apparatus of claim 1 wherein at least one plug fusible at a temperature within the limits of to 300 C. is disposed in the wall of said pressure fluid conduit.

5. A liquefied gas dispensing system, comprising in combination a tank, a liquid dispensing line connected with said tank, a pressure iluid conduit, a pump connected to said conduit to deliver fluid thereinto under pressure, a ilrst motor valve comprising a valve in said tank `connected to said dispensing line controlling flow of liquid from said tank through said dispensing line and a motor normally biasingV said valve closed, said motor being connected to said conduit and operated by fluid pressure therein to overcome its normal biasing effect and to open said valve, an orifice in said dispensing line for eifecting a pressure differential between a first and second point in said line responsive to liquid flow therein, a second motor valve comprising `a motor connected to said line at said points and operated by said pressure differential when it exceeds a predetermined value and a valve connected to said conduit between said pump and the motor of said first motor valve bleeding said conduit of iluid pressure when operated by said motor of said second motor valve, whereby said biasing means closes said valve in said line and stops liquid ilow in said line when said dinerential exceeds said predetermined value.

6. A liquefied gas dispensing system comprising in combination, a tank, a liquid dispensing line communicating with said tank, a pressure fluid conduit, means to establish fluid pressure in said conduit, a first motor valve comprising a valve in said line controlling flow of liquid from said tank, a motor controlling said valve and means biasing said valve closed, said motor being connected to said conduit and operated by fluid pressure therein to overcome said biasing means and open said valve, an orifice for effecting a pressure differential between a rst and second point in said line responsive to liquid flow therein, a second motor valve comprising a diaphragm motor connected at its high pressure side by a rst connecting conduit to said dispensing line at a point on the high pressure side of said orifice and connected at its low pressure side by a second connecting conduit to said dispensing line at a point on the low pressure side of said orifice and a normally closed valve connected to said pressure fluid conduit and moved to an open position when operated by said diaphragm motor, said diaphragm motor being operated by said pressure differential when it exceeds a predetermined value, whereby fluid pressure is bled from said conduit and said biasing means closes said valve in said line and stops liquid ow in said line when said differential exceeds said predetermined value, a check valve in said first connecting conduit permitting flow of fluid in a direction toward said-motor, a by-pass line around said check valve and an orifice in said by-pass line, a check valve in said second connecting conduit permitting flow of fluid in a direction away from said motor, a by-pass line around the last said check valve and an orifice in the last said by-pass line, whereby hysteresis of said second motor valve is provided so that after it has-been moved into an open position and then permitted to close it closes at a predetermined retarded rate and fluid pressure is vented from said pressure fluid conduit.

7. AA liquefied gas dispensing system, compris-v ing in combination, a tank, a liquid dispensing line communicating with said tank, a pressure fluid conduit, means to establish fluid pressure in said conduit, a first motor valve comprising a valve in said line controlling flow of liquid from said tank and a motor normally biasing said valve closed, said motor being connected to said conduit and operated by fluid pressure therein to overcome its normal biasing effect and open said valve, said dispensing line of predetermined length and size providing a pressure differential between a first and second point in said line responsive to liquid iiow therethrough, a second motor valve comprising a diaphragm motor connected on its high pressure side to a point in said dispensing line on the high pressure side of said pressure differential therein and connected on its low pressure side to a point in said dispensing line on the low pressure side of said pressure differential, and a normally closed valve connected to said pressure fluid conduit adapted to be moved to an open position when operated by said diaphragm motor, said diaphragm motor being operated by said pressure differential when it exceeds a predetermined value, and locking means for preventing automatic closure of said valve after it has been moved to an open position.

8. A liquefied gas dispensing system, comprising in combination, a tank, a liquid dispensing ,line communicating with said tank, a pressure fluid conduit, means to establish iiuid pressure in said conduit, a first motor valve comprising a valve in Said line controlling flow of liquid from said tank and a motor normally biasing said valve closed, said motor being connected to said conduit and operated by fluid pressure therein to overcome its normal biasing effect and open said valve, an orifice for effecting a pressure differential between a first and second point in said line responsive to liquid iiow therein, a second motor valve comprising a diaphragm motor connected on its high pressure side to said dispensing line at a point on the high pressure side of said orifice and connected on its low pressure side to said dispensing line at a point on the low pressure side of said orice and a normally closed valve connected to said conduit at a point intermediate said pressure establishing means and the motor of said first motor valve. said normally closed valve being adapted to be moved into an open position when operated by said diaphragm motor, said diaphragm motor being operated by said pressure differential when it exceeds a predetermined value, a piston chamber having an open end and a closed end and connected at its open end with the low pressure side of said diaphragm motor, a pressure-tight piston in said chamber connected with the diaphragm of said motor and adapted to be moved in said chamber in a direction away from said diaphragm when said normally closed valve is operated by said diaphragm motor to move into an open position, spring means in said chamber urging said piston in a direction towards said diaphragm, a conduit extending through said piston connecting the low pressure side of said diaphragm with the portion of said chamber intermediate its closed end and said piston, a check valve in the last said conduit on the diaphragm side of said piston permitting flow of fluid therethrough towards said diaphragm, and an orifice connecting said intermediate chamber portion with the low pressure side of said diaphragm.

9. A liquefied gas dispensing system, comprising in combination a tank, a liquid dispensing line connected with said tank, a pressurel iluid conduit, said conduit being disposed in parallel with and adjacent said liquid dispensing line, at least one plug fusible at a temperature within limits of -300" C. disposed in the wall of said conduit, a pump connected to said conduit to deliver iiuid thereinto under pressure, a first motor valve comprising a valve in said tank and connected to said dispensing line controlling flow of liquid from said tank through said dispensing line, a motor controlling said valve and means biasing said valve closed, said motor being connected to said conduit and operated by fluid pressure therein to overcome said biasing means and to open said valve, an orifice in said dispensing line for effecting a pressure diierential between a first and second point in said line responsive to liquid flow therein, a second motor valve comprising a diaphragm motor connected to said dispensing line at said points and operated by said pressure differential when it exceeds a predetermined value and a normally closed valve connected to said conduit at a point intermediate said pump and the motor of said first motor valve, said normally closed valve being operated by said diaphragm motor to move into an open position when said pressure differential exceeds said predetermined value, thereby bleeding said conduit of fluid pressure.

10. A liquefied gas dispensing system comprising in combination, a tank, a liquid dispensing line communicating with said tank, a pressure fluid conduit, means to establish fluid pressure in said conduit, a first motor valve comprising a valve in said line controlling flow of liquid from said tank, a motor controlling said valve and means biasing said valve closed, said motor being connected to said conduit and operated by fluid pressure therein to overcome said biasing means and open said valve, an orifice for effecting a pressure differential between a first and second point inv said line responsive to liquid flow therein, a second motor valve comprising a diaphragm motor connected at its high pressure side by a first connecting conduit to said dispensingline at a point on the high pressure Side 0i said orifice and connected at its low i i3 pressure side by a -second connecting conduit to said dispensing line at a point on the low pressure side of said orifice and a normally closed valve connected to said pressure fluid conduit and moved to an open position when operated by said diaphragm motor, said diaphragm motor being operated by said pressure differential when it exceeds a predetermined value, whereby fluid pressure is bled from said conduit and said biasing means closes said valve in said line and stops liquid flow ink said line when said differential exceeds said predetermined value, a check valve in said first connecting conduit permitting flow of fluid in a direction toward said motor, a bypass line around said check valve and an orificein said by-pass line, whereby hysteresis of said second motor valve is provided so that after it has been moved into an open position and then permitted to close it closes at a predetermined retarded rate and fluid pressure is vented from said pressure fluid conduit.

11. A liquefied gas dispensing system comprising in combination. a tank, a liquid dispensing line communicating with said tank, a pressure fluid conduit, means to establish fluid pressure in said conduit, a first motor valve comprising a valve in said line controlling flow of liquid from said tank, a motor controlling said valve and means biasing said valve closed. said motor being connected to said conduit and operated by uid pressure therein to overcome said biasing means and open said valve, an orice for effecting a pressure differential between a first and second point in said line responsive to liquid flow therea normally vclosed valve connected to said pres sure fluid conduit and moved to an open position when operated by said `diaphragm motor, s'aid diaphragmvmotor being operated by said pressure differential when it exceeds a predetermined value, whereby fiuid pressure is bled from said conduit and said biasing means closes said valve in said line and stops liquid iiow in said line when said differential exceeds said predetermined value, a check valve in said second connecting conduit permitting iiow of fluid in a direction away from said motor, a by-pass line around the last said check valve and an orifice in the last said bypass line, whereby hysteresis of said second motor valve is provided so that after it has been moved into an open position and then permitted to close it closes at a predetermined retarded rate and fluid pressure is vented from said pressure fluid conduit.

12. A iiuid dispensing system, comprising in combination, a tank, a fluid dispensing line in communication with said tank, a pressure fluid conduit, means to establish fluid pressure in said conduit, a first motor valve comprising a valve in said line controlling flow of uid from said tank, a motor controlling said -valve and means biasing said valve closed, said motor being connected to said conduit and operated by fluid pressure therein to overcome said biasing means and open said L valve, means for effecting a pressure differential between a first and second point in said line responsive to fluid ow therein, a second motor valve comprising a motor connected to said line at said points and operated by said pressure differential when it exceeds a predetermined value and a valve connected to said conduit between said uid pressure establishing means and the motor of said first motor valve bleeding said conduit of iiuid pressure when operated by said motor oi' said second motor valve, whereby said biasing means closes said valve in said line and stops fluid ow in said line when said differential exceeds said predetermined value.

DOYLE D. BUTTOLPH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Grindrod June 13, 1950

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