MECHANICAL OVERFILL PREVENTION VALVE INSERTABLE INSERTABLE INSIDE A FILLING PIPE.

Abstract

A cooperative overfill prevention valve with a standpipe includes a plug, a float, and a seat that do not exceed the diameter of the standpipe. The valve and standpipe can be inserted into a liquid holding tank from below. The rising liquid raises the float and plug until the plug seals against the seat. The float may be above the seat and connected to the plug by a rod that penetrates centrally through the seat. A check valve may allow drainage of the holding tank when liquid is withdrawn from the standpipe. The holding tank may be a fuel tank for a liquid fuel combustion torch. A central reservoir system may automatically fill a plurality of holding tanks fitted with the valves described therein and connected in series by a piping system.The filling process can be automatically terminated when a backpressure within the piping system exceeds a specific threshold.

Description

MECHANICAL OVERFILL PREVENTION VALVE INSERT I — INSIDE AN 8 u FILLING PIPE RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 142,225, filed on January 27, 2021. This application also claims the benefit of U.S. Provisional Application No. 63 / 208,811, filed on June 9, 2021. Both applications are incorporated herein by reference in their entirety for all purposes. FIELD OF INVENTION The invention relates to an apparatus for controlling the flow of fluid in a holding tank and, more particularly, to mechanical devices that prevent overfilling of a holding tank. BACKGROUND OF THE INVENTION There are many applications where it can be convenient to automatically limit the fill level of a holding tank or other liquid container. A very common example is the water holding tank of a flush toilet, for which there are many different designs in use that automatically open the fill valve when the tank is empty and close the fill valve when the water level in the tank reaches a desired "full" level. For most of these solutions, installing the fill-limiting mechanism in the holding tank or vessel to be filled requires easy access to the tank's interior. This allows for the insertion of a relatively large device into the tank, while a much smaller pipe or fitting extends through a hole provided at the bottom of the tank for connection to a filling pipe or hose. Furthermore, many of these designs are intended for filling a tank with water or another inert fluid, ensuring that exposure to the liquid is not toxic. This allows for a relatively complex design and, consequently, less reliable operation, because the mechanism is easily replaced without any health or environmental concerns, thus eliminating the need for the mechanism to be highly reliable over extended periods. > π r\ c N a However, there are applications where the interior of a liquid storage tank is inaccessible except perhaps through a few small ports, and where it is necessary to adapt the tank with a refilling mechanism to prevent overfilling. One example is the conversion of a liquid fuel torch, such as a "tiki" torch, from being manually refilled through a top fill port to being automatically refilled through a fuel line that enters the tank via a small port from below. When the interior of a liquid storage tank is not openly accessible, it can be difficult to implement a purely mechanical solution to prevent overfilling, because such a solution will generally require inserting a float or similar element into the tank through a large opening, such as the open top of the tank. Alternatively, one approach is to control the flow of liquid into the holding tank through a liquid filling pipe using an electrically controlled valve located on the outside of the holding tank. At least one liquid level sensor is then inserted into the holding tank through a small opening near the top. In the case of a tiki torch converted for automatic filling, for example, the level sensors can be inserted through the port near the top of the torch that was previously used for manually filling the fuel tank. A controller can then operate the electric valve based on the data from the level sensors, initiating filling when the tank is nearly empty and stopping the flow of liquid when it is nearly full.According to this approach, the required access to the interior is limited, at most, to only a small opening through which the filling pipe is inserted, and a small opening through which the level sensors are inserted. While this electronic approach can be effective, it can also be overly complex and expensive for some applications, especially when multiple holding tanks need to be automatically filled from a common source, due at least to the requirement of having an electric controller and valve associated with each tank. Furthermore, this approach may not be reliable enough for some applications because the electrically controlled valves and / or controllers may require periodic maintenance and / or replacement. > π r\ c N a What is needed, therefore, is a device for filling a liquid holding tank that can be inserted into the holding tank through a small opening, and that includes a simple, reliable, and purely mechanical overfill prevention valve. BRIEF DESCRIPTION OF THE INVENTION The present invention is an apparatus for filling a liquid holding tank. The apparatus can be inserted into the holding tank through a small opening and includes a simple, reliable, and purely mechanical overfill prevention valve. According to the present invention, a substantially straight pipe, referred to herein as the riser pipe, is inserted into the holding tank through a small port in the base of the tank and extends vertically into the tank. The riser pipe is essentially a liquid filling pipe configured to allow liquid to flow through it into the holding tank. A simple mechanical overfill prevention valve is included, either in series or fully contained within an upper portion of the standpipe. The overfill prevention valve includes a float that the liquid raises within the standpipe as the tank fills, and a seat that seals with a plug when the float has risen sufficiently. In some embodiments, the float also functions as the plug, while in others, the float and plug are separate components that are interconnected, so that the plug rises when the liquid raises the float. In some embodiments, during filling, the liquid flows through the seat and out the top of the standpipe.In other embodiments, liquid passages or fill ports are provided in the side wall of a standpipe, allowing liquid to flow into the tank without having to flow out of the top of the standpipe. Embodiments may also include overflow ports that penetrate the side wall of a standpipe to allow liquid from the tank to enter the standpipe and thus raise the float. In some models, the liquid storage tank is the fuel tank of a liquid-fueled torch, such as a so-called tiki torch. In some of these models, a small opening is formed in the bottom of the torch's fuel tank, through which the vertical pipe is inserted, for example, when converting the tiki torch from a manual filling configuration to an automatic filling configuration. The system modalities include a central liquid reservoir that is connected to a plurality of liquid filling pipes associated with a plurality of liquid holding tanks, as well as a pump that is configured to pressurize the liquid so that it flows into the holding tanks. In some of these configurations, the liquid in the liquid fill pipe is kept under pressure, so each holding tank is filled each time its overfill prevention valve is opened. As a result, a relatively constant liquid level is maintained in each liquid storage tank. In other configurations, each holding tank includes at least one electronic level sensor inserted through a port near the top of the tank. The level sensors are monitored by a single controller, which activates the pump whenever any sensor indicates a low liquid level. At that point, each holding tank fills until its overfill prevention valve is activated. In some of these configurations, the pump shuts off after a specified time interval, while others include additional level sensors in the holding tanks that indicate when the tank is full. The central controller then shuts off the pump when the sensors indicate that all tanks are full. In several configurations, the vertical pipe extends above the float to avoid interference between the float and other elements inside the tank, such as a level sensor or a torch wick. A first general aspect of the present invention is a liquid filling apparatus compatible for installation within a liquid holding tank, the liquid filling apparatus being configured to allow the filling of the liquid holding tank with the liquid while preventing the liquid from overfilling the holding tank.The liquid filling apparatus includes a standpipe having an outer wall; the standpipe is suitable for vertical insertion into the liquid holding tank; the standpipe is configured to allow liquid to flow through it into the liquid holding tank; and a liquid overfill protection valve that is in series with, or completely contained within, an upper portion of the standpipe. The liquid overfill protection valve has a valve diameter that is everywhere less than or equal to the diameter of a [missing information]. outer wall of the standpipe. The liquid overfill protection valve includes a central passage in liquid communication with the standpipe, a fill port in liquid communication with the inside of the holding tank, a valve seat penetrated by the central passage, a float, and a valve plug located within or below the valve seat and configured to be raised by the float to form a seal with a restricted region of the valve seat when the liquid holding tank is filled with the liquid. The liquid overfill protection valve is open when the valve plug is below the valve seat and closed when the valve plug is sealed against the valve seat. The liquid overfill protection valve, when open, is configured to allow liquid to flow from the standpipe through the center passage, through the fill port, and into the liquid holding tank. When closed, the liquid overfill protection valve is configured to prevent liquid from flowing from the standpipe into the liquid holding tank. In these modalities, the float is located above the valve seat and is interconnected with the valve plug by means of a rod or filament that extends from the float through the central passage of the valve seat to the valve plug. In any of the above modalities, the filling port can penetrate the valve seat, thereby providing liquid communication between the central passage of the valve seat and the interior of the liquid holding tank. In any of the above embodiments, the standpipe may extend above the float, with the float thus remaining within the standpipe when it is raised by the liquid and the valve is closed. Some of these embodiments also include at least one overflow port located above the restricted region of the valve seat and configured to ensure that the liquid level in the float is equal to the liquid level in the holding tank. Alternatively, the standpipe may extend both below and above the valve seat, but be interrupted by a region of the valve seat having an outside diameter equal to the outside diameter of the standpipe. In any of the above embodiments, the central passage can be configured to direct a flow of liquid through a flow path to the fill port without the liquid flow directly impinging on the valve plug. In some of these embodiments, when the liquid overflow prevention valve is open, the plug is suspended within a plug chamber that is in liquid communication with the liquid flow but is located below the flow path. Any of the above modalities may further include a drain valve configured to open automatically and allow liquid to flow from inside the holding tank into the standpipe when the liquid overfill prevention valve is closed and the liquid pressure in the holding tank is greater than the pressure in the stovepipe by more than one threshold pressure difference. Any of the above embodiments may further include a fill pipe inserted within the standpipe, a distal end of the fill pipe shaped to be redirected downwards, the valve seat installed within the downward-directed portion of the fill pipe, and the liquid filling apparatus configured when the liquid overfill prevention valve is open to allow liquid to flow through the fill pipe into the standpipe and from there into the liquid holding tank. In some of these embodiments, the valve plug is the float. Any of these embodiments may further include a constriction provided at the distal end of the fill pipe, the constriction configured to confine the valve plug so that it remains within the fill pipe. Any of the above configurations may further include an elastomeric sealing ring embedded in the restricted region of the valve seat and configured to form a seal with the valve plug when the plug is lifted to contact the sealing ring. Alternatively, the valve plug may be elastomeric and configured to form a liquid seal by direct contact with the valve seat. A second general aspect of the present invention is a liquid fuel combustion torch comprising a fuel tank having an interior, an insertion port provided at the bottom of the fuel tank, and a liquid filling apparatus according to the first general aspect, the liquid filling apparatus being inserted through the access port into the interior of the fuel tank. A third general aspect of the present invention is a system comprising a central liquid reservoir, a pump in liquid communication with the liquid reservoir, a plurality of liquid holding tanks, each of the liquid holding tanks having installed therein a corresponding liquid filling apparatus according to the first general aspect, and a liquid piping system interconnecting each of the liquid filling apparatuses with the pump. In some models, the liquid piping system interconnects the liquid filling devices in series. In either of the above modes, the system can be configured to maintain fluid pressure within the fluid piping system, automatically refilling each holding tank whenever its corresponding overfill prevention valve is open. Alternatively, the central controller can be configured to cause the pump to activate whenever the fluid pressure within the fluid piping system falls below a specified fill pressure, and to deactivate when the fluid pressure within the fluid piping system rises above the specified fill pressure. And in any of the above modes where the system is not configured to maintain liquid pressure within the liquid piping system, the central controller can be configured to cause the pump to shut off whenever the liquid pressure within the liquid piping system exceeds a specified fill pressure. The features and advantages as described herein are not all included, and in particular, many additional features and advantages will be apparent to a person skilled in the art from the Figures, the description, and the claims. Furthermore, it should be noted that the language used in the description has been selected primarily for instructional purposes and ease of reading, and not to limit the scope of the invention. BRIEF DESCRIPTION OF THE FIGURES Figure 1 is a cross-sectional illustration of a fuel combustion torch having a vertical pipe and a liquid overfill prevention valve according to a first embodiment of the present invention installed therein; Figure 2A is a cross-sectional view of the vertical pipe and liquid overfill prevention valve of Figure 1, shown in an open state; Figure 2B is a cross-sectional view of the vertical pipe and liquid overfill prevention valve of Figure 2A, shown in a closed state; Figure 3 is a cross-sectional view of the modality of Figures 2A; > π r\ c N to Figure 4A is a cross-sectional view of the vertical pipe and the liquid overfill prevention valve in a second embodiment of the present invention, shown in an open state; Figure 4B is a cross-sectional view of the second mode, shown in a closed state; Figure 5A is a perspective side view of a third embodiment of the present invention; Figure 5B is a cross-sectional side view of the third mode, shown in an open state; Figure 5C is a cross-sectional side view of the third mode, shown in a closed state; Figure 5D is a cross-sectional side view of a mode similar to the third mode, but which further includes a check valve that is configured to allow drainage of the holding tank when pressure is removed from the standpipe, even if the overfill prevention valve is closed; Figure 6A is a cross-sectional view of the vertical pipe and the liquid overfill prevention valve in a fourth embodiment of the present invention, shown in an open state; Figure 6B is a cross-sectional view of the fourth mode, shown in a closed state; Figure 7 is a horizontal cross-sectional view of the fourth embodiment; and Figure 8 is a perspective view of an embodiment of the system of the present invention that includes a plurality of liquid retention tanks that are automatically refilled from a common reservoir. DETAILED DESCRIPTION With reference to Figure 1, the present invention is an apparatus for filling a liquid holding tank 102. The apparatus can be inserted into the holding tank 102 through a small opening 106 provided at the bottom of the tank 102, and includes a simple, reliable, and purely mechanical overfill prevention valve 100 that does not require electrical power, a solenoid, etc. According to the present invention, a vertical pipe 104 is inserted into the tank 102 through the small port 106 provided at the base of the tank 102 and extends vertically > π r\ c N a into the interior of the tank 102. The vertical pipe 104 functions as a liquid filling pipe that is configured to allow the liquid to flow through it into the interior of the holding tank 102. In Figure 1, the holding tank 102 is a fuel tank for a tiki torch 108 that has been converted from a manual to an automatic filling configuration. The conversion involves forming the small opening 106 in the bottom of the fuel tank 102 and inserting the vertical pipe 104 through this opening into the tank. The tank also contains a wick 110 and a level sensor 112, which is sensed and controlled by a Wi-Fi-enabled plug 114 inserted through a port near the top of the tank. The level sensor 112 can be used, for example, to determine when the holding tank 102 is nearly empty, triggering a pump to begin refilling. The torch 108 also includes a small vent 116 that maintains the holding tank at ambient pressure.Although Figure 1 illustrates one embodiment that applies to a blowtorch, it should be understood that the scope of the present invention is not limited to blowtorch embodiments, but extends to all applications where a tank filling apparatus includes a liquid overfill prevention valve to be installed inside a liquid holding tank. With reference to Figures 2A and 2B, the overfill prevention valve 100 is inserted and contained within an upper portion of the vertical pipe 104. The overfill prevention valve 100 includes a float 200 that is raised by the liquid when the holding tank 102 is filled, and a seat 202 that is sealed by a plug 204 when the float 200 has risen a certain amount. In the embodiment of Figures 2A and 2B, the float 200 and the plug 204 are separate components that are interconnected by a wire or rod 206, such that the plug 202 rises when the float 200 is raised by the liquid.In the illustrated embodiment, an O-ring 208 is included within a tapered central passage 210 of the seat 202, so that the liquid 212 flows into the tank 102, as shown in Figure 2A, until the plug 204 is lifted high enough to be pressed into the O-ring 208, at which point the flow of liquid into the tank 102 is blocked, as illustrated in Figure 2B. In some embodiments, the incoming liquid flows past float 200 to flow into tank 102 from the top of the vertical pipe 104. In the embodiment of Figures 2A and > π r\ c N a 2B, filling ports 214 are provided on the side of the standpipe 104, so that the incoming liquid is not forced to flow past the float 200. The modality of Figures 2A and 2B also includes overflow ports 216 that ensure that the liquid is able to reach the float 200 when the liquid level outside the vertical pipe 104 rises above the float 200. Figure 3 is a cross-sectional illustration of the configuration in Figure 2A. It can be seen that four equally spaced filling ports 214 are provided in the side wall of the vertical pipe 104. Figures 4A and 4B illustrate an embodiment similar to that of Figures 2A and 2B, except that the overfill prevention valve 100 is installed in series with the standpipe 104, rather than being entirely contained within the standpipe 104. In the illustrated example, the overfill prevention valve 100 includes a stem 400 that is press-fitted onto the top of the standpipe 104. In similar embodiments, the stem 400 is attached to the top of the standpipe 104 by threaded insertion, adhesive, or any other coupling means known in the art. The diameter of the seat 202 in this embodiment is the same as the diameter of the standpipe 104, except for the stem 400, which is inserted into the standpipe 104. The seat 202 in this embodiment further includes a collar 402 that extends upward to surround the float 200 so that the float 200 can be lifted by the incoming liquid 212 within the collar 402, thereby eliminating any concern that the float 200 might come into contact with any other structure within the holding tank 102, such as a wick 110 or a level sensor 112. The collar 402 is essentially an extension of the standpipe 104 above the seat 202. Another difference between the embodiment of Figures 2A and 2B and the embodiment of Figures 4A and 4B is that the embodiment of Figures 4A and 4B does not include an O-ring 208. Instead, when the float 200 is lifted, the plug 204 forms a seal directly with the tapered central passage 210 of the seat 202. In the embodiments, the plug is made of an elastic material, such as synthetic rubber or compressible plastic, so that a liquid-tight seal is formed between the plug 204 and the seat 202 without the need for an O-ring 208. Figure 4A illustrates the embodiment in its open configuration, while Figure 4B illustrates the embodiment in its closed configuration. > π r\ c N a Figure 5A is a perspective view of a modality that functions similarly to the — Figures 2A-2B, but where the liquid is routed so that it does not directly impact the plug 204 as the liquid flows from the standpipe 104 into the holding tank 102. Instead, with reference to the cross-section of Figure 5B, the plug 204 is suspended within a plug chamber 500 that is in fluid communication with the liquid flow into the holding tank 102, but is located below the liquid flow path, so that the plug 204 is offset from the flow path. This approach avoids any concern that the rapidly flowing liquid during the filling of the holding tank 102 could push the plug 204 up into the seat 202 before it is lifted by the float 200, thereby prematurely closing the valve 100, and possibly causing repeated opening and closing of the valve 100 as it fills. Figure 5B shows valve 100 in its open configuration, while Figure 5C is a cross-section figure illustrating the mode of Figure 5B when valve 100 is closed. With reference to Figure 5D, the embodiments of the present invention further include a check valve 502 that allows liquid to drain from the holding tank 102 even if valve 100 is closed. The check valve, which functions as a liquid drain valve, is normally closed whenever there is liquid pressure within the riser pipe 104. However, the check valve 502 is configured to open automatically when the liquid pressure within the riser pipe 104 falls below a specified pressure threshold, thereby allowing any liquid within the holding tank to drain from the holding tank 102, even if the valve is closed, if the liquid is removed from the riser pipe 104.This feature can be advantageous, for example, when the invention is implemented in a fuel-burning torch 108, because it can allow the torch 108 to be turned off remotely simply by draining or pumping the liquid fuel out of the vertical pipe 104, thereby emptying the holding tank 102, so that the torch 108 is turned off as soon as the remaining fuel in the wick 110 is exhausted. Figures 6A and 6B are cross-sectional views of another embodiment of the present invention, wherein an internal filling pipe 600 is included within the vertical pipe 104. The upper portion of the internal filling pipe 600 is curved substantially by 180 degrees, so that the opening at the distal end of the liquid filling pipe 600 faces downward. In this embodiment, the plug 204 is included within the downward-facing region of the pipe. Liquid filling 600, and is floating, so a separate float is not needed. A flange or lip 602 is installed inside the end of the liquid filling pipe 600, and functions to prevent the plug 204 from falling out of the liquid filling pipe 600 when the standpipe 104 is not filled with liquid. Fill ports 604 are provided on the side of the liquid fill pipe 600 near the plug 602, and an O-ring 208 is provided over the fill ports 604. In the illustrated embodiment, the O-ring 208 functions as the seat 202 of the liquid overfill prevention valve. When the plug 204 is not pressed against the O-ring 208, as shown in Figure 6A, the incoming liquid is able to flow readily from the liquid fill pipe 600 through the fill ports 604 into region 606 within the standpipe 104 surrounding the liquid fill pipe 600, and from there through the fill ports 214 and / or out through the top of the standpipe 104 into the holding tank 102. When the rising liquid lifts plug 204 and presses it against O-ring 208, as illustrated in Figure 6B, the incoming flow of liquid is blocked. Figure 7 is a horizontal cross-sectional illustration of the modality of Figure 5A. It can be seen in the Figure that the incoming liquid 212 flows from the liquid filling pipe 600 through the filling ports 604 into the space 606 between the liquid filling pipe 600 and the vertical pipe 104, and from there through the filling ports 214 into the holding tank 102. With reference to Figure 8, the system embodiments include a central liquid reservoir 802 connected in series to a plurality of liquid filling pipes 804 associated with a plurality of devices 108, including liquid storage tanks 102, as well as a pump 810 configured to pressurize the liquid so that it flows into the liquid storage tanks 102. In some of these embodiments, the liquid in the liquid filling pipes 804 is kept pressurized so that the storage tanks 102 are automatically refilled each time their overfill prevention valves 100 are opened. As a result, a relatively constant liquid level is maintained within each liquid storage tank 102. In the illustrated embodiment, the devices 108 are liquid fuel combustion torches.If the check valve of Figure 5D is included in the valves 100 within the torches 108, then the torches 108 > π r\ c N a can be shut off by reversing the direction of the pump, thereby draining the fuel from É — the liquid filling pipes 804 and the standpipes 104. u. In the specified modes, the operation of pump 810 stops after a fixed operating time has elapsed, or upon detecting backpressure in the filling pipes 804 that exceeds a specified maximum, indicating that all overfill prevention valves 100 are closed. In the illustrated mode, each of the liquid storage tanks 102 includes at least one electronic level sensor 112 inserted through a port provided near the top of the liquid storage tank 102. The level sensors 112 are monitored by a single centralized controller 806, which activates pump 810 whenever any of the sensors 112 indicates a low liquid level, at which point each of the liquid storage tanks 102 is filled until its overfill prevention valve 100 closes.The options include additional level sensors in the liquid storage tanks 102 that detect when the holding tank 102 is full, and the central controller 806 shuts off pump 810 when the sensors indicate that all the tanks 102 are full. This approach can be advantageous, for example, to prevent the spillage of significant quantities of liquid if one of the overfill prevention valves 100 fails to close for any reason. The foregoing description of the embodiments of the invention has been presented for illustrative and descriptive purposes. Each and every page of this document, and all content hereafter characterized, identified, or numbered in any way, is considered an integral part of this application for all purposes, regardless of its form or placement within the application. This description is not intended to be exhaustive or to limit the invention to the precise embodiment described. Many modifications and variations are possible in light of this description. Although the present application is presented in a limited number of embodiments, the scope of the invention is not limited to these embodiments but is subject to various changes and modifications. The description presented herein does not describe all possible combinations of features that fall within the scope of the invention. The features described herein by the various embodiments can generally be interchanged and combined in any non-contradictory combination without departing from the scope of the invention. In particular, the limitations presented in the dependent claims below can be combined with their corresponding independent claims in any number and in any order without departing from the scope of this description, unless the dependent claims are logically incompatible with each other.

Claims

1. A liquid filling apparatus compatible for installation within a liquid holding tank, the liquid filling apparatus is configured to allow the filling of the liquid holding tank with the liquid while preventing the liquid from overfilling the holding tank, the liquid filling apparatus comprising: a standpipe having an outer wall, the standpipe being suitable for vertical insertion into the liquid holding tank, the standpipe being configured to allow the liquid to flow through it into the interior of the liquid holding tank;and a liquid overfill protection valve that is in series with or completely contained within an upper portion of the standpipe, the liquid overfill protection valve having a valve diameter that is everywhere less than or equal to the diameter of an outer wall of the standpipe, the liquid overfill protection valve comprising: a central passage in liquid communication with the standpipe; a fill port in liquid communication with the interior of the holding tank; a valve seat penetrated by the central passage; a float;and a valve plug located within or below the valve seat and configured to be raised by the float to form a seal with a restricted region of the valve seat when the liquid holding tank is filled with the liquid; the liquid overfill prevention valve is open when the valve plug is below the valve seat and is closed when the valve plug is sealed against the valve seat; the liquid overfill protection valve, when open, is configured to allow liquid to flow from the standpipe through the center passage, through the fill port, and into the liquid holding tank; the liquid overfill protection valve, when closed, is configured to prevent liquid from flowing from the standpipe into the liquid holding tank. > π r\ c N a; 2. The liquid filling apparatus according to claim 1, wherein the float is located on the valve seat and is interconnected to the valve plug by a rod or filament extending from the float through the central passage of the valve seat to the valve plug.

3. The liquid filling apparatus according to claim 1, wherein the filling port penetrates the valve seat, thereby providing liquid communication between the central passage of the valve seat and the interior of the liquid holding tank.

4. The liquid filling apparatus according to claim 1, wherein the vertical pipe extends above the float, the float thus remaining within the vertical pipe when the float is lifted by the liquid and the valve is closed.

5. The liquid filling apparatus according to claim 4, further comprising at least one overflow port located above the restricted region of the valve seat and configured to ensure that the liquid level in the float is equal to the liquid level in the holding tank.

6. The liquid filling apparatus according to claim 1, wherein the vertical pipe extends both below and above the valve seat, but is interrupted by a region of the valve seat having an outside diameter equal to the outside diameter of the vertical pipe.

7. The liquid filling apparatus according to claim 1, wherein the central passage is configured to direct a flow of liquid through a flow path towards the filling port without the liquid flow directly impinging on the valve plug.

8. The liquid filling apparatus according to claim 7, wherein when the liquid overflow prevention valve is open, the plug is suspended within a plug chamber that is in liquid communication with the liquid flow but is located below the flow path. > π r\ c N a 9. The liquid filling apparatus according to claim 1, further comprising — a drain valve configured to open automatically and allow liquid to flow from inside the holding tank into the standpipe when the liquid overfill prevention valve is closed and the liquid pressure in the holding tank is greater than the pressure in the stovepipe by more than one threshold pressure difference.

10. The liquid filling apparatus according to claim 1, further comprising a filling pipe inserted within the standpipe, a distal end of the filling pipe being shaped to be redirected downwards, the valve seat being installed within the downward-directed portion of the filling pipe, the liquid filling apparatus being configured when the liquid overfill prevention valve is open to allow the liquid to flow through the filling pipe into the standpipe, and from there into the liquid holding tank.

11. The liquid filling apparatus according to claim 10, wherein the valve plug is the float.

12. The liquid filling apparatus according to claim 10, further comprising a constriction provided at the distal end of the filling pipe, the constriction being configured to confine the valve plug so that it remains within the filling pipe.

13. The liquid filling apparatus according to claim 1, further comprising an elastomeric sealing ring included in the restricted region of the valve seat and configured to form a seal with the valve plug when the valve plug is lifted to come into contact with the sealing ring.

14. The liquid filling apparatus according to claim 1, wherein the valve plug is elastomeric and is configured to form a liquid seal by direct contact of the same with the valve seat.

15. A liquid fuel combustion torch comprising: a fuel tank having an interior; a wick extending into the fuel tank from the top of the fuel tank; an insertion port provided in the bottom of the fuel tank; and a liquid filling apparatus according to claim 1, the liquid filling apparatus being inserted through the access port into the interior of the fuel tank.

16. A system comprising: a central liquid reservoir; a pump in liquid communication with the liquid reservoir; a central controller configured to control the pump; a plurality of liquid fuel combustion torches according to claim 15; and a liquid piping system interconnecting each of the liquid fuel combustion torch fuel tanks with the pump.

17. The system according to claim 16, wherein the system is configured to maintain the liquid pressure within the liquid piping system, each of the holding tanks being automatically refilled in this manner whenever its corresponding liquid overfill prevention valve is open.

18. The system according to claim 16, wherein the central controller is configured to cause the pump to activate whenever the liquid pressure within the liquid piping system falls below a specified filling pressure.

19. The system according to claim 16, wherein the central controller is configured to cause the pump to shut off whenever the liquid pressure within the liquid piping system rises above a specified filling pressure.

20. The system according to claim 16, wherein the central controller is configured to cause the pump to shut off after a specified operating time has elapsed.

21. The system according to claim 15, wherein the vertical pipe extends above the float and thereby prevents interference between the float and the wick.

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