Patent Application
20070144612
1. Field of the Invention
Apparatuses and methods consistent with the present invention are generally related to storage tanks and are specifically related to storage tank filling systems which prevent overflow during and subsequent to filling and to storage tank venting systems for venting a storage tank to the atmosphere efficiently and environmentally.
2. Description of the Related Art
It is well known to use storage tanks for holding a variety of fluids such as oil, gasoline, and diesel fuel to name a few. Proper filling of storage tanks is a universal concern, as overfilling of storage tanks may result in spillage, damage to the tank or filling equipment, contamination of land or ground water, or other serious and potentially dangerous results. Concerns over spillage of the tank contents are particularly acute when the tank contents are flammable, toxic and/or environmentally hazardous.
Spillage from fuel tanks on pleasure boats and other marine vessels is particularly troublesome. Some contemporary estimates of such fuel spillage are in excess of six million gallons annually in the United States alone. Globally, fuel spillage is many times this amount. The resultant fuel losses are economically and ecologically detrimental in terms of wasted fuel resources and environmental contamination.
An internal fuel tank on a marine vessel is typically provided with a vent to enable vapor and fumes to escape under pressure while fuel is being pumped into the fuel tank via the fuel fill tube. As the engine consumes fuel, air is drawn into the tank via the air vent to fill the space from the consumed fuel. Venting is also necessary to accommodate expansion of the fuel when it is heated. Conventionally, during filling of the fuel tank, some fuel may be discharged through the vent into the water as the attendant attempts to fill the tank to capacity. In fact, it is not unknown for filling attendants to purposely fill the tank until fuel is discharged from the vent, using this as an indication that the tank is completely full. It is also possible that fuel may be discharged through the vent subsequent to filling. For example, fuel can be discharged through the vent in a tank filled to capacity as a result of the boat listing from side to side due to waves, wind or other causes. Also conventionally, fuel may be discharged through the vent in a tank filled to capacity if a subsequent rise in ambient temperature causes the fuel to expand.
The use of fuel dispensing nozzles that automatically shut off the flow of fuel to the tank when the tank is full have been used to avoid fuel spillage during filling. These nozzles typically operate by sensing a pressure change at an end of the nozzle that results from fuel backing up within the tank fill tube. Use of a fuel dispensing nozzle with automatic shut-off will prevent fuel discharge through the fill tube during filling if the fill tube is properly designed to trigger the shut-off at the appropriate time. However, with many designs the automatic shut-off may be triggered only to have fuel surge out of the vent or out of the tank fill tube because of pressure trapped in the tank. Because of the location of the vent in many applications, it is also possible that fuel will be discharged through the vent during filling. Discharge through the vent may also occur after filling, even if the automatic shut-off is triggered. For example, if the tank is filled to near capacity, fuel can be discharged through the vent due to boat listing or fuel expansion.
A conventional nozzle 10 is illustrated in
Some prior approaches to preventing spillage rely on the use of a reservoir designed to capture overflow. However, these approaches require additional parts and the use of a reservoir takes up more space on the vessel. None of these approaches addresses the above-mentioned drawbacks of relying on the automatic shut-off feature of existing fuel dispensing nozzles.
Accordingly, there is a need for a system and method that prevents spillage both during and after filling of a storage tank. It would be desirable to have such a system and method of overflow prevention that facilitates use of automatic shut-off nozzles and does not require provision of an overflow reservoir.
According to an exemplary embodiment of the present invention, a system for preventing overflow in a storage tank which is fillable via a nozzle inserted in a fill passage, includes a nozzle stop, a sealing device, and an airtight passage. The nozzle stop is disposed within the fill passage, and when an end of the nozzle is in contact with the nozzle stop, the nozzle is in a fill position. The nozzle stop may have an inner lip, wherein an inner diameter of the inner lip is smaller than an outer diameter of the end of the nozzle. The sealing device is disposed within the fill passage, above the nozzle stop. The sealing device includes a first inner seal and a second inner seal, disposed, respectively, below and above a hole in the nozzle when the nozzle is in the fill position. The first seal and the second seal form a first sealing space around the hole in the nozzle. The airtight passage is an airtight passage between the inner sealing space and an interior of the storage tank.
According to one exemplary aspect of the present invention, the sealing device may further include a hole disposed between the first inner seal and the second inner seal, a first outer seal below the hole, and a second outer seal above the hole, thus forming an outer sealing space in communication with the inner sealing space. The airtight passage may include the hole in the sealing device, the outer sealing space, a hole in the fill passage, and a pressure transfer passage between the hole in the fill passage and the storage tank.
According to another exemplary aspect of the present invention, the sealing device may further include a passage therein between the inner sealing space and the fill passage. The airtight passage may then include the passage in the sealing device, and a pressure transfer passage, within the fill passage, between the sealing device and an interior of the storage tank.
According to another exemplary embodiment of the present invention, a venting system for a storage tank fillable via a nozzle, includes a fill passage, a fill fitting, a positioning sleeve, a tank vent passage, and an atmospheric vent passage. The fill passage connected the storage tank to an external atmosphere and has a hole therein. The fill fitting includes a sleeve fitted within the fill passage and has a hole therein corresponding to the hole in the fill passage. The positioning sleeve is disposed within the fill fitting and has a substantially cylindrical central portion with an inner diameter larger than an outer diameter of the nozzle. The positioning sleeve also has an upper flange with at least one hole therein, and a lower flange. The holes in the fill passage and in the fill fitting lie between the upper and lower flanges of the positioning sleeve. The tank vent passage is a passage between the storage tank and the hole in the fill passage, such that the storage tank communicates with the external atmosphere via the tank vent passage, the hole in the fill passage, the hole in the fill fitting, and the hole in the upper flange of the positioning sleeve. The atmospheric vent is a passage between the tank vent passage and the external atmosphere. The atmospheric vent passage is connected to the tank vent passage via first and second valves. The first valve is a check valve which permits passage of air from the atmosphere to the tank vent passage, but which does not permit passage of air from the tank vent passage to the atmosphere. The second valve is a pressure relief valve which permits passage of air at a pressure of greater than or equal to a specific pressure from the tank vent passage to the atmosphere and prevents passage of air at a pressure of less than the specific pressure.
The specific pressure may be 1 psi or greater.
The above and other exemplary aspects of the present invention will become better understood with reference to the following description and accompanying drawings, which should not be read to limit the invention in any way, in which:
As illustrated, a fuel tank 100 connects to a fill passage 110 through which the fuel tank 100 may be filled. The term “fill passage” refers to a passage from a storage tank to the exterior of a vehicle for the purposes of filling the storage tank. It may also be referred to as a fill hose. The fill passage 110 may be flexible. It should be understood that the present invention is not limited to fuel tanks, but may include another type of tank to be filled, as would be understood by one of skill in the art.
A fill fitting 120 is mounted in an outer end of the fill passage to receive a fill nozzle, for example nozzle 10, as illustrated in
The sleeve extension 122 of the fill fitting 120 fits inside the fill passage 110. A stop 124 and holes 128 and 129 in the fill fitting will be described further in conjunction with the sealing device and nozzle stop, below.
A nozzle 10 inserted into the open end of the fill passage 110 within the fill fitting 120 is stopped in a fill position by a nozzle stop 130. An exemplary nozzle stop is illustrated in
A sealing device 140, disposed within the fill fitting 120 above the nozzle stop 130, provides a first inner seal around the nozzle below the position of the hole 17 and a second inner seal around the nozzle above the position of the hole 17, when the nozzle is in the fill position. Exemplary sealing devices are illustrated in
A positioning sleeve 150, disposed within the fill fitting 120 above the sealing device 140, fits around an upper portion of an inserted nozzle to maintain the nozzle in a properly-centered position. Alternately, the positioning sleeve 150 may maintain an inserted nozzle in a position which is off-center from the central axis of the fill tube, as needed, as would be understood by one of skill in the art. An exemplary positioning sleeve 150 is illustrated in
According to exemplary aspects of the present invention, the nozzle stop 130, the sealing device 140, and the positioning sleeve 150 may be formed as one or two unified pieces, as illustrated in
As mentioned above, and as illustrated in
A pressure transfer passage extends downward from the hole in the fill fitting into the tank. The pressure transfer passage 170, a lower hole 111 in the fill passage, the hole 128 in the fill fitting 120, the outer sealing space 147, the hole 146 in the sealing device 140, and the inner sealing space 145, thereby form a path from the interior of the fuel tank to the hole in the nozzle. The lower end 171 of the pressure transfer passage 170 is disposed at a predetermined level 175 within the fuel tank. The pressure transfer passage 170 may be formed from nylon or other plastics, copper, brass, steel, stainless steel, aluminum, or flexible hose, or any other appropriate material as would be understood by one of skill in the art. For systems on boats, materials which meet the American Boat and Yacht Council Standards, or are approved by the US Coast Guard for use in marine vessel fuel storage systems may be used.
As fuel is dispensed through the fill nozzle 10, through the fill passage 110, and into the tank 100, the fuel level rises in the tank. During fuel fill, the negative pressure in the nozzle passage 16 (described above with respect to
As further illustrated in
The venting system 180 includes a tank vent passage 160 which extends from a lower end at the tank 100 to an upper end which communicates with the atmosphere through an upper hole 112 in the fill passage, an upper hole 129 in the fill fitting 120, and the at least one hole 154 the upper flange 153 of the positioning sleeve 150. The venting system 180 includes an atmospheric vent 165 which provides a means for air flow from the atmosphere into the tank 100 as fuel in the tank is depleted. The atmospheric vent 165 includes a first valve 163, which is a check valve permitting air flow only from the atmosphere into the tank and preventing air or fuel flow from the tank to the atmosphere. A second valve 162 is a pressure relief valve which prohibits air flow from the atmosphere to the tank, and which permits air flow to the atmosphere only at a pressure of 1-2 psi or greater. The combination of the first valve 163 and the second valve 162 enables air to enter the tank 100 as the fuel in the tank is consumed. Additionally, in case of a malfunction in the nozzle, the combination of valves prevents excess fuel from discharging through the atmospheric vent 165 and contaminating surrounding land or water. The pressure valve 162 enables flow through the atmospheric vent only in extreme cases, for example if the temperature in the fuel tank caused enough expansion to require additional air release.
Although the above exemplary embodiments and aspects of the present invention have been described, it will be understood by those skilled in the art that the present invention should not be limited to the described exemplary embodiments, but that various changes and modifications can be made within the spirit and scope of the present invention without departing from the spirit and scope of the present invention as defined by the following claims.
