US3812888A

US3812888A - Compressed liquid gas filling system

Info

Publication number: US3812888A
Authority: US
Inventors: C Dalton
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-08-25
Filing date: 1972-08-25
Publication date: 1974-05-28
Anticipated expiration: 1991-05-28

Abstract

Escaping gas from the 20 percent valve of a compressed liquid gas tank is fed through a metered opening into an expansion chamber. A temperature sensitive element located within the expansion chamber has a first ambient temperature position and a second lower temperature position. The escaping gas normally has the same temperature position. The escaping gas normally has the same temperature as the ambient; however, as the tank is filled beyond the 80 percent volume position, liquid gas is drawn into the expansion chamber where it immediately expands and vaporizes. The expanding process draws heat from the immediate surroundings, thereby lowering the temperature of the expansion chamber and the temperature sensitive element which assumes the second temperature position. Movement of the temperature sensitive element is coupled with a spring-loaded control valve feeding the compressed liquid gas tank, thereby closing the spring-loaded valve and stopping the filling process.

Description

United States Patent Dalton May 28, 1974 COMPRESSED LIQUID GAS FILLING Primary Examiner-Leon G. Machlin SYSTEM [76] Inventor: Charles Robert Dalton, 3107 57 ABSTRACT Newton, No. 40, Torrance, Calif. 90505 Escaping gas from the 20 percent valve of a compressed liquid gas tank is fed through a metered open- 122] Flled: 1972 ing into an expansion chamber. A temperature sensi- [21] 3 g tive element located within the expansion chamber has a first ambient temperature position and a second lower temperature position. The escaping gas nor- [52] US. Cl 141/39, 62/49, 73/298, n has the same temperature position The eseap 116/118 R, 137/ 101- ing gas normally has the same temperature as the am- [51] Int. Cl. Bg 5/00 hieht; however, as the tank is fill d beyond the [58] new of Search 141/192 cent volume position, liquid gas is drawn into the ex- 141/45, Wino/ P; H6/DIG- 118 R; pansion chamber where it immediately expands and 73/290 298; 251/66 67, 74; 137/59 vaporizes. The expanding process draws heat from the 207'5, 214 immediate surroundings, thereby lowering the temperature of the expansion chamber and the temperature [56] References Cted sensitive element which assumes the second tempera- UNITED STATES PATENTS ture position. Movement of the temperature sensitive 2,630,818 3/1953 McRae 251/66 x element is coupled with a Spring-loaded Control valve 2,850,257 9/1958 Smith et al 251/66 X feeding the compressed liquid gas tank, thereby clos- 3,293,390 12/1966 Shaw 116/118 R ing the spring-loaded valve and stopping the filling 3,550,603 12/1970 Schueler 251/74 X rocegg 3,606,980 9/1971 Simpson et al. 251/66 X 20 Claims, 9 Drawing Figures I8 20% I I4 vu or I 1' vopor l6 1 I h ii-TE 1 1 10 E i (Prior Art) QATENTEDMMH m: 3,812,888

SHEET 10F 3 24 Fig. 5%; 40"

IL/ /V M. 77 ii? I "f."

PATENTED MY 28 9 3.812 8 8 8 SHEU 2 0F 3 100 Top View Fig. 5.

1 COMPRESSED LIQUID GAS FILLING SYSTEM This invention relates to a method and means for automatically filling a compressed liquid gas fuel tank to a predetermined volume.

Compressed liquid gas does not exist in nature in the liquid state but rather must be manufactured or compressed into a liquid. There are basically three kinds of compressed gases in use today; and they include liquid petroleum gas, commonly known as LPG, liquid natural gas, commonly known as LNG, and compressed natural gas, commonly known as CNG. All three gases are compressed and stored under pressure, however, only LPG and LNG are stored as a liquid under pressure. The compressed natural gas (CNG) is normally stored under at least 2,000 pounds per square inch pressure and is always stored as a gas and never as a liquid.

The present invention is concerned primarily with the automatic handling of compressed liquid gases of the LPG or LNG type. Reference to compressed liquid gas is intended to include all compressed gases stored under pressure as a liquid.

Propane is part of the LPG gas family and is also known as LP gas. The initials LPG refer to liquified petroleum gas which is produced as one of the many byproducts of the refing of pretroleum. The LP gas is produced by either stripping heavy products from natural gas or from refineries where crude oil is refined into gasoline, kerosene, diesel fuel and other petroleum products. The LP gas is a natural product of this refining process. Propane is part of the LP gas family which which is also commonly known as butane, bottled gas or tank gas.

Propane is basically a colorless, odorless liquid that will remain in a liquid state as long as it is under pressure. For commercial applications an odorant is normally added to the propane gas in order to give the user an indication of the presence of the gas. Propane boils (turns into a vapor) at minus 44C, and as the fuel temperature varies from minus 44C to plus 100C, the propane molecules become more volatile and hence boil more rapidly. This low boiling temperature of the propane liquid gas and the high volatility of the propane molecules as the temperature increases causes the liquid propane when released to atmosphere to vaporize instantly into a completely vaporized gas.

For combustion engine applications, the completely vaporized propane gas when entering the carburetor assures an even gas/air mixture to all cylinders thereby resulting in more complete combustion. As a result of having a more efficient combustion there is less carbon deposits, longer spark plug life and less oil dilution associated with the internal combustion engine.

Unfortunately, the low boiling point of the LP gas creates a problem in holding the liquid gas in the fuel tank associated with the user vehicle. Normally the LP gas fuel tank is designed and constructed to hold a volume of liquid gas at a pressure of approximately 350 pounds per square inch. In view of the low boiling point of the LP gas and the fact that the LP gas fuel tank holding the gas under pressure is subjected to external ambient temperatures that may exceed 100 F, it can be appreciated that the propane molecules located within the fuel tank will boil more rapidly as the temperature increases. thereby increasing the internal pressure within the gas tank.

Conventional safeguards require that all LP fuel gas tanks be designed and constructed and tested to withstand at least 1,000 pounds of static pressure which is approximately 3% to four times the relief valve setting. ln addition, all LP gas tanks are required to have a pressure overload control valve (POC) which is sometimes in combination with the feed valve for automatically releasing excess pressure from within the gas tank. An additional safeguard is the requirement that LP fuel gas tanks only be filled to percent of their volume capacity in order to thereby allow 20 percent of the volume of the gas tank for expansion purposes as the external ambient temperature changes.

The so-called 20 percent valve is an external valve communicating inside the LP gas fuel tank with a vapor liquid level tube that is inserted a predetermined distance into the gas tank to represent 20 percent of the internal volume. The opening through the walls of the fuel tank is approximately the size of a No. 54 drill to thereby ensure that in the event of an accident that the only fuel that would escape to atmosphere would be through the small 54 drill-size opening. During the filling operation the 20 percent valve is opened, thereby allowing vapor within the gas tank to escape through the liquid level tube, indicating to the operator that the liquid level tube is in the presence of vapor only.

Filling the LP gas tank with liquid gas raises the level of the liquid within the fuel tank until the liquid level reaches the liquid level tube. At that point the internal pressure within the tank forces a small portion of liquid LP gas up the liquid level tube and out the external 20 percent valve. The LP gas in the liquid state when released to atmosphere pressures immediately vaporizes causing a squirting of gas in the form of a heavy white fog indicating to the operator that the liquid level within the tank has reached the 80 percent portion. The operator then immediately shuts off the fuel pump, closes the 20 percent valve and closes the fill valve on the fuel hose of the LP fuel tank.

The present invention is concerned with giving the operator a visual indication that the fuel tank has reached the 80 percent level. In addition, there is disclosed an apparatus for automatically turning off the fuel supply when the tank is filled to the 80 percent level without requiring any attendance from the operator. In connection with the above, there is disclosed apparatus for recycling the vented gas vapors that are normally released to atmosphere during the filling pro cess.

In the present invention there-is described an expansion chamber having a metered input that is connected to a LP gas fuel tank through a vapor liquid level tube extending into the gas tank. The liquid level tube will normally be inserted a distance into the volume of the gas tank to represent 20 percent of the total volume of the tank and at the other end will communicate with the expansion chamber through a metered opening. Located within the expansion chamber is a temperature-sensitive element capable of generating an output in the presence of a change in temperature. The actual sensitive element may include a thermister, resistor, thermocouple or thermal pressure bulb-type actuator for generating an electrical or mechanical signal in the presence of a change in temperature or a bimetallic material for generating a physical movement in the presence of a change in temperature.

Y manner through the FCC valve. As the gas tank is filled, the vapor located within the tank is forced through the liquid level tube into the expansion chamher and out the vent hole located within the chamber. There is however, no change of temperature associated with the vapor since the vapor is already in a completely vaporized state, and the temperature of the vapor within the tank or within the expansion chamber will be the same, and hence there will be no effect of the vaporized gas on the thermometal disk which will remain in the normal ambient first temperature positron.

As the liquid level rises beyond the 80 percent volume position, a portion of the LP liquid gas will be forced through the liquid level tube, through the metering opening and into the expansion chamber. The liquid gas upon entry into the expansion chamber will immediately vaporize thereby absorbing heat and in the process of expanding and vaporizing will remove heat from the surrounding expansion chamber. Lowering the temperature of the expansion chamber and the thermometal disk causes the thermometal disk to assume the second cooler temperature position; and in so doing, the spring-biased actuating rod is moved into a second position for either closing the fuel valve or for operating an indicator to show that the tank is full.

The vaporized gases located within the expansion chamber may be exposed to the atmosphere for normal venting as is presently done with the conventional percent valve. However, in the preferred embodiment the vent may be connected to the suction line associated with the fuel pump for recirculating the vapors within the system so as to prevent pollution of the atmosphere by the vaporized gases.

In the preferred embodiment a spring-loaded fuel valve is used inconnection with feeding liquid LP gas into the fuel tank. The expanding liquid gas is used to cool a bi-metal member for operating a normally closed fuel valve. The vaporizing of the liquid gas against the thermometal material cooperating with a spring-loaded fuel valve results in the closing of the spring-loaded fuel valve into the OFF position without the need of an operator observing or not observing the stated conditions.

Further objects and advantages of the present invention will be made more apparent by referring now to the accompanying drawings wherein:

FIG. 1 is a block diagram of a conventional system for filling compressed liquid gas fuel tanks;

FIG. 2 is a sectional diagram of an expansion chamber illustrating a thermometal disk in the ambient or first temperature position;

FIG. 3 illustrates an expansion chamber having a thermometal disk in a cool or second temperature position;

FIG. 4 illustrates a block diagram of a complete system for filling liquid gas fuel tanks according to the teachings of the present invention in which normally vented vapors are recirculated within the system;

FIG. 5 illustrates a second embodiment for recirculating normally vented vapors within the system;

FIG. 6 illustrates the top view of a spring-loaded valve that is normally biased in the OFF position;

FIG. 7 is a bottom view of the spring-loaded fuel valve illustrating the biasing spring;

FIG. 8 is a schematic diagram illustrating how the spring-loaded fuel valve is automatically shut off when the fuel tank approaches percent of the total volume; and

FIG. 9 is a block diagram illustrating how the expansion chamber and plunger may be used to automatically operate a spring-loaded fuel valve.

Referring now to FIG. I, there is shown a block diagram illustrating the prior art techniques for filling a compressed liquid gas fuel tank 10. Located on one side of the fuel tank 10 and preferably on the uppermost side is a liquid fill valve 12 and together with a 20 percent valve 14. A liquid level tube 16 projects within the fuel tank 10 a distance equal to 20 percent of the total volume of the tank. The upper end of the liquid level tube 16 is connected to the controllable 20 percent valve 14.

The compressed liquid gas supply is normally maintained at service stations in substantially large fuel tanks 18 under pressure. A fuel pump 20 is used to connect the output from the fuel tank 18 into the liquid fill valve 12 associated with the LP fuel tank 10.

In normal filling operation the connection is made as illustrated in FIG. 1 with the liquid fill valve 12 opened and the 20 percent valve 14 opened. The pump 20 forces liquid gas under pressure from tank 18 into tank 10. As the liquid level within the tank 10 rises beyond the 80 percent level, a portion of the liquid will enter the liquid level tube 16 and be forced out the 20 percent valve 14. The operator by necessity must stand near the tank being filled in order to observe the white foamy material which indicates that liquid is being vaporized in the atmosphere as it emerges from the 20 percent valve 14. The operator then stops the pump 20, closes the 20 percent valve 14 and the liquid fill valve 12, and removes the coupling between the pump 20 and the valve 12. At this point the fuel tank 10 is now filled to within 80 percent of the volume capacity leaving 20 percent of the volume for vapor expansion as the ambient temperature changes.

From the foregoing description of the prior art techniques it can be appreciated that an operator must remain in close proximity to the filling of. the tank in order to prevent overfilling. This requirement places a severe restriction on the commercial applicability and use of compressed liquid gas systems for automobiles and other mass transportation media. The present invention is considered a break-through in that it is now possible to use automatic means for filling the LP gas tank without requiring an operator to be in immediate attendance during the filling procedure. It is now possible for the operator to service a plurality of different vehicles at the same time with the same facility that a single operator now services a plurality of vehicles at a conventional gasoline dispensing station.

Referring now to FIG. 2, there is shown an expansion chamber 22 formed within a block 24 and insert 26. Block 24 is shown mounted external to a LP fuel tank 28. However, the block may be formed as part of the fuel tank as an integral part or external to the fuel tank as shown. A vapor liquid level tube 30 is inserted into the fuel tank a distance equivalent to 20 percent of the volume and at the other end communicates with a metering orifice 32 located in block 24 that communicates with the expansion chamber 22. A controllable vent 34 communicates the interior of the expansion chamber 22 to the outside atmosphere. A locking screw 36 provides a means for either opening or closing the vent 34.

Located within the expansion chamber 22 is a thermometal disk 38 located in a sealing relationship between block 24 and insert 26. An O-ring 40 located within a channel in block 24 provides a seal for the thermometal disk 38 which is illustrated in a first ambient temperature position.

Located on the other side of the disk 38 is a springbiased actuating rod 42 having an enlarged head portion 44. The head portion 44 has a first side 46 for con tacting the thermometal disk 38 and a substantially square shoulder side 48 that is opposite the rounded side 46. Insert 26 contains a cylindrical opening 50 for accepting the actuating rod 42 and a substantially larger cylindrical opening 52 for accepting a spring 54 that is located within the cylindrical opening 52. Spring 54 continually urges the head portion 44 of the plunger 42 to continually contact the thermometal disk 38.

FIG. 2 illustrates a quiescent condition in a fuel tank where the liquid level is below the level of the liquid level tube 30. The vapor within the upper portion of the tank also enters the liquid level tube 30 and the expansion chamber 22. However, this vapor is at ambient temperature and will not affect the thermometal disk 38 which will remain in the normal warm temperature position.

Referring now to FIG. 3, there is shown the same embodiment comprising an expansion chamber 22 illustrated in connection with FIG. 2. In FIG. 3, however, the fuel tank 28 is being filled with liquid gas and the captive screw 36 is opened thereby allowing the vent 34 to communicate the interior of the expansion chamber 22 with the outside atmosphere. During the filling operation the vapor normally located in the upper portion of the tank 28 is forced through the liquid level tube 30, through the expansion chamber 22 and out the vent 34 to the atmosphere. The vapor being at ambient temperature will have no effect upon the thermometal disk 38.

However, once the liquid level reaches the lower tip of the liquid level tube 30, liquid is forced through the liquid level tube and through the metered opening 32 which communicates the liquid level tube 30 with the interior of the expansion chamber 22. The compressed liquid gas upon being forced through the orifice 32 into the expansion chamber 22 immediately expands and vaporizes causing an immediate heat loss in the environment of the expansion chamber 22. The resultant lowering of the temperature within the expansion chamber 22 cools the thermometal disk 38 which now assumes a cooled second temperature position as indicated. Flexing of th thermometal disk 38 causes the indicating rod 42 to be pushed out of the confined insert 26, thereby causing the tip of the actuating rod to be used either as an actuating mechanism to be described further or as an indicator to the operator that the gas tank is 80 percent full. The vaporized gas within the expansion chamber 22 is removed by the vent 34 to the outside atmosphere.

The inventive concept is predicated on the proposition that the metered liquid from the orifice 32 upon entering the expansion chamber 22 will immediately vaporize and cool the thermometal disk 38 located within the expansion chamber. Since the cooling process is based upon the transient condition, it is recognized that should the operator not stop the filling process that liquid gas from the tank 28 may fill the expansion chamber 22 and be emitted from the vent 34 as a liquid which would then vaporize into the atmosphere and in this condition would not continue to cool the thermometal disk 38. In order to prevent the plunger 42 from being withdrawn it is suggested that the thermometal disk 38 have a mechanically preferred cold position as shown in FIG. 3 that requires the manual resetting of the element 38 back to the warm position. This would mean that after the thermometal disk 38 has been cooled and assumed the position shown in FIG. 3 that subsequent warming of the thermometal disk will not cause the disk to return to the warm position as shown in FIG. 2 until the operator depressed the plunger 42, causing the metal disk 38 to be mechanically replaced into the warm position. This fail-safe feature will ensure that once the actuating arm 42 is operated that the operating arm will remain in the operated position until manually reset by the operator.

Referring now to FIG. 4, there is shown a block diagram of a complete filling system utilizing the principle of the present invention and which illustrates how the venting gas from the expansion chamber may be withdrawn into the system and prevented from being re leased to the atmosphere as a contaminating gas. A pump 40 having an inlet side 42 is connected to a source of liquid gas 44. An output 46 from the pump 40 is connected to a liquid fill valve 48 attached to a fuel tank 50. An expansion chamber 52 communicating with the interior of the tank 50 by means of a liquid level tube 54 has a vent opening 56 connected to the suction side 58 of the pump 40.

During the filling operation the pump 40 supplies gas from the source 44 through the liquid fill valve 48 into the interior of the tank 50. Escaping vapors from inside the tank are fed through the vapor liquid level tube 54 into the expansion chamber 52 and out the vent hole 56 back into the suction side 58 of the pump 40, thereby effectively recirculating all venting gases from inside the tank 50. The process will continue until the liquid level rises and allows liquid to fill the liquid level tube 54 which liquid will be injected through the metering orifice into the expansion chamber 52 and vaporized, thereby cooling the thermometal disk 62 and forcing the actuating rod 60 into an operating condition. The operator on seeing the actuating rod will stop the pumping operation of pump 40, close the FCC valve 48, and cap the venting tube 56 associated with the expansion chamber 52. It can be appreciated therefore that during the filling operating all gases normally vented through the expansion chamber 52 will be pulled back into the pump 40 and recirculated until the tank 50 is filled thereby ensuring that no gases will be released to the atmosphere during the filling operation.

Referring now to FIG. 5, there is shown another embodiment for recapturing the venting gases during the filling operation so as to prevent contamination of the atmosphere. In this embodiment the block 66 and the insert 68 forming the expansion chamber 70 is made an integral part of the tank shell 72. In all other respects the vapor liquid level tube 74 communicating with the expansion chamber 70 and the thermometal disk 76 located within the expansion chamber and the vent opening 78 leads to the jet pump for evacuating gases from the expansion chamber 52. Also located on the tank shell 72 is a liquid fill valve 80 having a fitting 82 for accepting the nozzle from the pump 40 illustrated in FIG. 4. The liquid fill valve 80 has a large internal diameter 84 and a small projection defining a reduced diameter 86 for effectively providing a low pressure area commonly known as a Venturi effect in the area 88 between reduced diameter 86 and the enlarged diameter 84 of the liquid fill valve 80. The reduced diameter portion 88 is communicated by means of an internal connection 90 with the vent opening 78 associated with the expansion chamber 70.

In operation, liquid being inserted into the liquid fill valve 80 through the fill fitting 82 will cause a low pressure area due to the Venturi effect that will effectively draw the accumulated gases within the expansion chamber 70 through the vent 78 and into the main stream of fluid passing within the liquid fill valve 80. This process will continue as long as liquid fuel is inserted through the liquid fill valve 80. In other words, all gases accumulating within the expansion chamber 70 will be continuously purged and recycled within the tank and prevented from being expelled into the atmosphere.

It will also be appreciated by those skilled in the art that the block 66 and the insert 68 forming the expansion chamber 70 may be located as part of the tank shell 72 as illustrated in FIGS. 2 and 3. In the external configuration the connection 90 between the vent 78 and the low pressure area 88 associated with the liquid fill valve will be external to the tank shell 72 rather than internal as illustrated. In any event, the operation will be the same which is to prevent external vapors from escaping into the atmosphere.

Referring now to FIGS. 6, 7, 8 and 9, there is disclosed apparatus for utilizing the change of state of the escaping liquid fuel from a liquid state to a gaseous state as the means for controlling a spring-loaded fuel valve 90 that is normally biased in the OFF position.

Referring now to FIGS. 6 and 7, there is shown a spring-loaded fuel valve 90 that is biased by a spiraled spring 92 into the normally closed position. The operating handle 94 controls the internal valve operating mechanism and is attached on the top side as illustrated in F IG. 6 to a cam 96 and on the bottom side to the spiraled spring 92. A stop 98 located on the body of the valve 90 limits the movement of the cam 96 by abutting against a flat surface 100 located on the cam. A detent or notch 102 is cut in the cam 96 approximately 90 from the flat surface 100. The notch 102 is adapted to receive a locking member that will hold the operating arm 94 in the open position. When the locking member is retracted from the notch 102, the spiral spring 92 is free to rotate the operating arm 94 to the closed position with the cam surface 100 abutting against the stop member 98.

Referring now to FIG. 8, there is shown a first embodiment for automatically shutting off the fuel supply valve feeding the liquid fill valve 80 on a fuel tank. There is illustrated an automatic shut-off valve 90 similar to that described in connection with FIGS. 6 and 7. Located on one side of the valve by means of screws 104 is a bi-metallic strip 106 that has a normally preferred warm position against the valve body and a cool position that is away from the valve body. The free or cantilevered end 108 of the bi-metallic strip 106 is adapted to fit into the notch 102 cut into the cam 96.

In the normal warm position, the bi-metallic strip 106 V is located close to the valve body 90 so that tip 108 is located within the notch 102 thereby holding the valve operating arm 94 in the open position.

The conventional 20 percent valve 110 located on the tank shell 112 is connected by means of a flexible tube 114 to the valve body 90 where the free end of the tube 116 faces the bimetallic 106 so that fumes from the 20 percent valve 110 will completely envelop the bi-metallic strip 106. As mentioned previously in connection with the expansion chamber illustrated in FIGS. 2 and 3, the normal vapors escaping from the vapor liquid level tube 111 associated with the 20 percent valve 110 will conduct vapors that are at the ambient temperature. Since there is no change of state of the vapors when exposed to the expansive atmosphere, there is therefore no change in the temperature of the vapors.

The change of temperature is associated only with the expansion of the liquid gas when it is conducted to either the expansion chamber associated with FIGS. 2 and 3 or to the expansive atmosphere in which the bimetallic strip 106 is located as illustrated in FIG. 8. The liquid gas fed from the 20 percent valve 110 through the tube 114 will normally be removed at the tip 116 as a liquid. As soon as the liquid hits the atmosphere it immediately expands and vaporizes thereby cooling the immediate area which is the bi-metallic strip 106 causing the strip to be cooled and thereby fold away from the main body of the valve 90. Movement of the bimetallic strip 106 will cause the tip 108 to be displaced from the detent 102 located in the cam 96. With the cam 96 no longer held in a restraining position by the tip 108, the operating arm 94 is free to move into the normally closed position by the action of the biased spring 92. It can be appreciated therefore that as soon as the liquid level within the tank sheet 112 approaches the 20 percent volume area that the vaporizing liquid from the tip 116 will cool the bi-metallic strip 106, thereby immediately closing the valve 90 in a safe and automatic fashion.

Referring now to FIG. 9, there is shown a second embodiment for automatically controlling an automatic shut-off valve in response to the liquid level approaching more than 80 percent of the total volume of the fuel tank. The system described in connection with FIG. 9 contemplates the use of an expansion chamber 120 formed from a block 122 and an insert 124 in a similar fashion as described in connection with FIGS. 2 and 3. The essential difference is that the thermometal 126 has a normally warm ambient position so as to force the actuating rod 128 against the action of a spring 130 into a normally extended position as shown. In all other respects the system is similar to that previously described with the liquid level tube 132 extending through the tank shell 134 a distance equal to approximately 20 percent of the internal volume of the tank 134. A vent 136 is connected to the suction side of a pump 138 for removing all vapors from the interior of the expansion chamber 120. One end of the pump 138 is connected to a tank 140 of compressed liquid gas which is pumped through a spring biased valve 142 of the type described and illustrated in connection with FIGS. 6 and 7.

The normally extended plunger 128 is adapted to fit within the detent 102 of the cam 96 as illustrated in FIG. 6 thereby holding the operating arm 144 in the open position against the operation of the coil spring 92 as illustrated in FIG. 7. The discharge end of the automatic shut-off valve 142 is connected to the liquid fill valve 146 located on the tank 134.

In the normal filling operation, the liquid fill valve 146 is open and the operating arm 144 of the automatic shut-off valve 142 is moved to the open position with the normally extended plunger 128 inserted into the detent 102, located on the cam 96. The pump 138 is turned ON and compressed liquid from the storage tank 140 is forced into the tank 134. As the liquid level of fiuid rises and contacts the bottom portion of the liquid level tube 132, a metered amount ofliquid is forced from the liquid level tube 132 into the expansion chamber 120 where it is vaporized and cools the thermometal disk 126, causing the disk 126 to move into a lower position in view of the cooling action caused by the vaporizing liquid within the chamber 120. The thermometal disk 126 under the urging of spring 130 will cause the plunger 128 to be retracted a distance sufficient to allow the end portion of the plunger to pull free of the detent 120 in the cam 96. With the cam no longer restrained by the extended plunger 128 the operating handle 144 is now free to move into the OFF position under the urgings of the coiled spring 92. Once the automatic shut-off valve 142 has operated, all fuel from the storage tank 140 is prevented from entering the tank 134. The attending operator need only stop the pump 138 and close the liquid fill valve 146, remove the necessary lines, and cap the vent with a suitable cover of the type shown in FIGS. 2 and 3. Due to the fail-safe feature of the spring-biased valve 90, there is no danger if the expansion chamber 120 floods, since the valve would already have tripped The system described in connection with FIG. 9 has an inherent advantage over the automatic system described in connection with FIG. 8 since the vapor fumes from either the 20 percent valve or from the vent associated with the expansion chamber is now recycled and kept in the system without contaminating the atmosphere.

I claim:

1. A system for filling compressed liquid gas tanks under pressure comprising:

an expansion chamber having a metered input adapted to be connected to a compressed liquid gas tank for receiving a selected portion of the total tank contents,

a temperature-sensitive element located within said expansion chamber for generating an output on the expansion of said liquid to a gas in said chamber, and

a controllable vent communicating with said expansion chamber for removing accumulated gas from said chamber.

2. A system according to claim 1 which includes a vapor liquid level tube communicating said said expan- 65 sion chamber at one end and inserted a predetermined distance into the compressed liquid gas tank whereby liquid gas in said tank at a predetermined level is fed into said expansion chamber where it expands and thereby cools said temperature sensitive element.

3. A system according to claim 2 in which said compressed liquid gas tank has an upper portion and a 5 lower portion and said vapor liquid level tube is inserted a distance equal to approximately 20 percent of the volume of said tank whereby liquid gas filling more than 80 percent of the volume of said tank causes liquid to enter said tube and said expansion chamber.

4. A system according to claim 1 in which said temperature-sensitive element comprises a bi-metallic material having a preferred position under ambient temperature conditions and a second position under less than ambient temperature conditions.

5. A system according to claim 1 in which said temperature sensitive element comprises a flexible thermometal disk held in a sealing relationship within said expansion chamber for defining a first portion of said chamber that is sealed from said compressed liquid gas tank.

6. A system according to claim 5 which includes a movable plunger located within said first portion of said chamber and is continuously urged against one side of said disk,

said plunger extending in said expansion chamber and moving as said flexible thermometal disk moves.

7. A system according to claim 6 in which said movable plunger comprises an elongated stem portion extending through said expansion chamber and an enlarged head portion, I

said head portion having a first side for contacting said disk and a second square side defining a sealing shoulder whereby extreme movement of said plunger causes said sealing shoulder to cover and seal the opening in said expansion chamber filled by said elongated stem.

8. A system according to claim 6 which includes indicia means controlled by said movable plunger whereby filling the compressed liquid gas tank to the predetermined volume is automatically indicated.

9. A system according to claim 1 which includes a pumping means connected to said controllable vent in said expansion chamber for removing accumulated gas from said chamber.

10. A system according to claim 1 which includes means for pumping said accumulated gas from said vent in said expansion chamber back into said compressed liquid gas tank.

11. An automatic system for filling compressed liquid gas tanks under pressure comprising:

a service valve continuously biased in the OFF position adapted to be connected to a source of-compressed liquid gas,

a temperature-sensitive element open to the atmosphere having a first temperature position and a second temperature position coupled to said service valve for holding said valve open when in said first position and allowing said valve to close when in said second position, and a vapor liquid level tube adapted to be inserted a predetermined distance into a compressed liquid gas tank at one end and at the other end communicating with said temperature sensitive element for feeding said liquid gas against said element. 12. A system according to claim 11 in which an external hose is connected at one end to a 20 percent valve associated with a compressed liquid gas tank and at the other end is directed against said temperature-sensitive element.

13. A system according to claim 11 which includes a spring attached to said valve for continually urging said valve into the OFF position.

14. A system according to claim 11 in which said valve includes a cam having a detent position attached to said valve and in which said temperature-sensitive element includes a bimetallic spring adapted to fit into said detent for holding said valve open against the spring action when in said first temperature position.

15. An automatic system for filling compressed liquid gas tanks under pressure comprising:

a service valve continually biased in the OFF position adapted to be connected to a source of compressed liquid gas,

a temperature-sensitive element having a first temperature position and a second temperature position located within said expansion chamber and coupled with said service valve for holding said valve open when in said first temperature position and allowing said valve to close when in said second temperature position, and

a controllable vent communicating with said expansion chamber for removing accumulated gas from said chamberi whereby liquid gas in said tank at a predetermined level is fed into said expansion chamber where it expands and thereby cools said temperature-sensitive element.

17. A system according to claim 15 in which said temperature-sensitive element comprises a flexible thermometal disk held in a sealing relationship within said expansion chamber for defining a first portion of said chamber that is sealed from said compressed liquid gas tank.

18. A system according to claim 17 which includes a movable plunger located within said first portion of said chamber and is continuously urged against one side of said disk,

19. A system according to claim 15 which includes a pumping means connected to said controllable vent in said expansion chamber for removing accumulated gas from said chamber.

20. A system according to claim 15 which includes means for pumping said accumulated gas from said vent in said expansion chamber back into said compressed liquid gas tank.

Claims

1. A system for filling compressed liquid gas tanks under pressure comprising: an expansion chamber having a metered input adapted to be connected to a compressed liquid gas tank for receiving a selected portion of the total tank contents, a temperature-sensitive element located within said expansion chamber for generating an output on the expansion of said liquid to a gas in said chamber, and a controllable vent communicating with said expansion chamber for removing accumulated gas from said chamber.

2. A system according to claim 1 which includes a vapor liquid level tube communicating said said expansion chamber at one end and inserted a predetermined distance into the compressed liquid gas tank whereby liquid gas in said tank at a predetermined level is fed into said expansion chamber where it expands and thereby cools said temperature sensitive element.

3. A system according to claim 2 in which said compressed liquid gas tank has an upper portion and a lower portion and said vapor liquid level tube is inserted a distance equal to approximately 20 percent of the volume of said tank whereby liquid gas filling more than 80 percent of the volume of said tank causes liquid to enter said tube and said expansion chamber.

6. A system according to claim 5 which includes a movable plunger located within said first portion of said chamber and is continuously urged against one side of said disk, said plunger extending in said expansion chamber and moving as said flexible thermometal disk moves.

7. A system according to claim 6 in which said movable plunger comprises an elongated stem portion extending through said expansion chamber and an enlarged head portion, said head portion having a first side for contacting said disk and a second square side defining a sealing shoulder whereby extreme movement of said plunger causes said sealing shoulder to cover and seal the opening in said expansion chamber filled by said elongated stem.

11. An automatic system for filling compressed liquid gas tanks under pressure comprising: a service valve continuously biased in the OFF position adapted to be connected to a source of compressed liquid gas, a temperature-sensitive element open to the atmosphere having a first temperature position and a second temperature position coupled to said service valve for holding said valve open when in said first position and allowing said valve to close when in said second position, and a vapor liquid level tube adapted to be inserted a predetermined distance into a compressed liquid gas tank at one end and at the other end communicating with said temperature sensitive element for feeding said liquid gas against said element.

12. A system according to claim 11 in which an external hose is connected at one end to a 20 percent valve associated with a compressed liquid gas tank and at the other end is directed against said temperature-sensitive element.

15. An automatic system for filling compressed liquid gas tanks under pressure comprising: a service valve continually biased in the OFF position adapted to be connected to a source of compressed liquid gas, an expansion chamber having a metered input adapted to be connected to a compressed liquid gas tank for receiving a selected portion of the total tank contents, a temperature-sensitive element having a first temperature position and a second temperature position located within said expansion chamber and coupled with said service valve for holding said valve open when in said first temperature position and allowing said valve to close when in said second temperature position, and a controllable vent communicating with said expansion chamber for removing accumulated gas from said chamber.

16. A system according to claim 15 which includes a vapor liquid level tube, communicating with said expansion chamber at one end and inserted a predetermined distance into the compressed liquid gas tank, whereby liquid gas in said tank at a predetermined level is fed into said expansion chamber where it expands and thereby cools said temperature-sensitive element.

18. A system according to claim 17 which includes a movable plunger located within said first portion of said chamber and is continuously urged against one side of said disk, said plunger extending in said expansion chamber and moving as said flexible thermometal disk moves.