Patent Publication Number: US-2023148173-A1

Title: Water level indicator, method of manufacture thereof and articles comprising the same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Application No. 62/989,304, filed on Mar. 13, 2020, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Disclosed herein is a water level indicator, a method of manufacture thereof and articles comprising the same. 
     Floating roofs are often used for liquid storage tanks. Floating roofs are often equipped with one or more pontoons for increasing the buoyancy of the roof. A floating roof suitably equipped with pontoons (a) decreases the weight of the roof; (b) reduces the number of parts used in the construction of the roof; (c) increases the stability of the roof under all conditions; (d) insures efficient drainage of water from the top side of the roof and eliminates the possibility of an excessive quantity of rain water collecting and remaining on the roof; and (e) reduces the cost of manufacturing and erecting the roof. 
     There is therefore need for a floating mechanism that is more sensitive to water level in the pontoon tank so that immediate advance warning is provided to technicians who are responsible for roof maintenance. 
     SUMMARY 
     Disclosed herein is a water level indicator for a pontoon tank comprising a float mechanism that comprises a support mechanism that does not move; wherein the main support mechanism is fixedly attached to a manway cover that protects the pontoon tank; an extension system with an extension rod adjustment system that contacts the main support mechanism at a first end and that contacts a float at a second end that is opposed to the first end; and a movable portion that comprises a plurality of levers; wherein the movable portion contacts the main support mechanism and the extension system; and wherein the plurality of levers act cooperatively to displace a gauge rod in proportion to a fluid level in the tank. 
     Disclosed herein too is a method for manufacturing a water level indicator for a pontoon tank comprising contacting a support mechanism with an extension system and a movable portion that comprises a plurality of levers to form a float mechanism for the pontoon tank; wherein the support mechanism is fixedly attached to a manway cover that protects the pontoon tank; wherein the extension system comprises an extension rod adjustment system that contacts the support mechanism at a first end and that contacts a float at a second end that is opposed to the first end; and wherein the movable portion comprises a plurality of levers; wherein the movable portion contacts the main support mechanism and the extension system; and wherein the plurality of levers act cooperatively to displace a gauge rod in proportion to a fluid level in the tank. 
     Disclosed herein is a water level indicator for a pontoon tank comprising a float mechanism that comprises a support mechanism that does not move; wherein the main support mechanism is fixedly attached to a manway cover that protects the pontoon tank; an extension system comprising an extension rod that contacts a float at a one end and a gauge rod at n end that is opposed to the end that contacts the float; where the support mechanism contacts the extension rod at its mid-section; and where a displacement of the float is transmitted to the gauge rod causing it to be proportionately displaced. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
         FIG.  1    depicts a conventional commercially available pontoon; 
         FIG.  2    is a schematic depiction of a pontoon with the water level indicator that is in operative communication with a sensitive floating mechanism; 
         FIG.  3    is a depiction of the extension system with an extension rod adjustment system of the  FIG.  2   ; 
         FIG.  4    is another schematic depiction of a pontoon with the water level indicator that is in operative communication with a sensitive floating mechanism; 
         FIG.  5 A  is a schematic depiction of the water level indicator that is fitted into the pontoon tank; 
         FIG.  5 B  is a schematic depiction of the water level indicator as it is being removed from the pontoon tank; and 
         FIG.  5 C  is another schematic depiction of the water level indicator as it is being removed from the pontoon tank. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein is a water level indicator that is in operative communication with a sensitive floating mechanism (hereinafter float mechanism) for use in pontoons/bulkheads that increase the buoyancy of floating roofs having liquid storage tanks (hereinafter floating roof tanks) contained thereon. The float mechanism comprises a plurality of levers that enable greater sensitivity and detection of the presence of fluids such as rain water and other chemicals that may accumulate in the pontoon/bulkhead thereby causing buoyancy issues and damage to the floating roof. 
     A floating roof tank is typically used for storing highly volatile liquids such as crude oil and gasoline. Recently, the capacity of the floating roof tanks has rapidly increased with increase in the consumption of fuel and the capacity of a tankers that transport a great volume of petroleum. This has given rise to the problem that the pontoon type floating roof is sunk or destroyed due to loads by rainwater or petroleum accumulated in the pontoon/bulkhead and going unnoticed. 
     It is therefore desirable to provide a safety pontoon type floating roof for liquid storage tanks, which prevents the roof from being damaged due to loads such as rainwater or other fluids (e.g., fluids produced in the plant such as liquid chemicals) accumulated thereon. It is also desirable to provide a pontoon type floating roof for liquid storage tanks which is capable of effectively and rapidly draining liquid, such as, for example, rainwater, which might otherwise accumulate on the roof. On manner of accomplishing this is to use a tank with a water level indicator for the pontoons/bulkheads that has greater sensitivity to and can detect the presence of fluids (such as rain water and chemicals) that may accumulate in the pontoon/bulkheads creating buoyancy issues thereby causing damage to the floating roof. 
     In an embodiment, the water level indicator for the pontoon tank comprises a float mechanism that comprises a support mechanism that does not move. The main support mechanism is fixedly attached to a manway cover that provides access to the pontoon. The extension system comprises an extension rod that contacts a float at a one end and a gauge rod at the end opposite to the end that contacts the float. The support mechanism contacts the extension rod at its mid-section. The displacement of the float is transmitted to the gauge rod causing it to be proportionately displaced.  FIG.  1    depicts one embodiment of a pontoon  100  that facilitates buoyancy of the floating roof and drainage of fluids (such as water and chemicals) from the top side of the roof and attempts to eliminate the possibility of an excessive quantity of rain water collecting and remaining on the roof. 
     The fluids are generally in the liquid state. The pontoon  100  comprises a tank  120  (also known as the pontoon/bulkhead  120 ) with an opening  122 . The opening  122  permits access to the inside of the pontoon/bulkhead  120  and is contacted by a manway cover  118 . The manway cover  118  provides access to the pontoon/bulkhead  120  via the opening  122 . The manway cover  118  has fixedly attached thereto a floating mechanism  124  that measures fluid level in the tank and provides an indication of the amount of fluid collected in the pontoon/bulkhead. 
     The floating mechanism  124  comprises a main support mechanism (that is fixed) comprising two vertical beams  106 A and  106 B and a horizontal beam  108  that is fixedly attached to the a first end of both vertical beams  106 A and  106 B. The second end of the vertical beams  106 A and  106 B is fixedly attached to the bottom side of the manway cover  118 . The top side of the manway cover  118  faces the ambient atmosphere. A lever  110  has a first end that is fixed to the main support mechanism. The lever  110  is fixed and does not move. It contacts a first lever  113  (also called the extension rod  113 ) at its midsection  114 . The first lever  113  pivots about point  114 . 
     A gauge rod  102  having a scale  104  attached thereto slides through a passage in the manway cover  118  and the horizontal beam  108 . The scale  104  provides a visual indication of the height of the fluid in the tank  120 . A float  116  is attached to one end of first lever  113 , while the other end of the first lever  113  rotatably pivots about the bottom of the gauge rod  102 . 
     When fluid (e.g., water) collects in the pontoon/bulkhead  120 , the float  116  begins to become buoyant thus causing the gauge rod  102  to change its position via motion transmitted to it via the first lever  113 . The change in position of the gauge rod  102  as read on the scale  104  is indicative of the amount of fluid collected in the tank  120 . The device in the  FIG.  1    is designed to reflect a leverage ratio of 0.5 to 1 to 1.5:1, preferably 0.8:1 to 1.2:1. The leverage ratio is the ratio of vertical lift of the float to the vertical change in position of the gauge rod. For example, when the float  116  lifts 1 inch (2.54 centimeters) and the gauge rod  102  moves 1 inch in the vertical direction (either upwards or downwards in response to an upward motion of the float), the leverage ratio is calculated to be 1:1. In an embodiment, the entire floating mechanism  100  can be removed from the tank  120  (as a single piece) through the opening  122  by removing the manway cover. 
     While the device shown in the  FIG.  1    is capable of indicating water level in the pontoon/bulkhead  120 , the float mechanism designs detailed below in the  FIGS.  2  to  4    are more sensitive and have leverage ratios of 1:1.8 to 1:5, preferably 1:2 to 1:4. 
     With reference now to the  FIG.  2   , a pontoon  200  comprises a tank  230  with an opening  231  that is protected by a manway cover  232 . Affixed to the manway cover  232  is a float mechanism that comprises a main support mechanism that does not move and is always fixed, an extension system with an extension rod adjustment system and a movable portion that contains a plurality of levers. The fixed main support mechanism works in conjunction with the extension rod adjustments and the movable portion (that contains a plurality of levers) to cause a displacement in the gauge rod  202 , when a fluid such as water or chemicals collect in the pontoon/bulkhead  230 . 
     The main support mechanism comprises two vertical beams—a first vertical beam  206 A and a second vertical  206 B, both of which contact a horizontal beam  204 . The first vertical beam  206 A is longer than the second vertical beam  206 B by an amount of 10 to 50%, preferably 20 to 40%, based on the length of the second vertical beam  206 B. In addition to the beams  206 A,  206 B and  204 , the main support mechanism comprises a first inclined beam  208  that is fixedly attached to the first vertical beam  206 A. 
     A second inclined beam  216  contacts the first inclined beam  208  and rotatably pivots about point  304 . The second inclined beam  216  can rotate about the first inclined beam  208  at point  304  and can contact it (the first inclined beam  208 ) anywhere along its length. In an embodiment, the second inclined beam  216  contacts the first inclined beam  208  a distance between ⅓ (one—third) and ½ (one-half) of the distance as measured from its (the first inclined beam  208 ) point of contact with the first vertical beam  206 A. 
     In an embodiment, the main support mechanism is fixed. In other words, the vertical beams  206 A and  206 B do not move relative to each other or with respect to the horizontal beam  204 . Similarly, the first inclined beam  208  is fixed and does not move with respect to the beams  206 A,  206 B and  204 . The first inclined beam and the beams  206 A,  206 B and  204  can be fixedly attached to each other by welding, by using adhesives, or by using other forms of fastening such as bolts, screws, nuts, and the like. 
     The length of the second inclined beam  216  is selected such that it rotates anticlockwise when the float  224  buoys itself due to the presence of a fluid in the tank  230 . This will detailed later. 
     The extension system comprises three beams—a first extension beam  218 , a second extension beam  220  and an extension adjustment rod  222 . The first and second beams  218  and  220  can move with respect to each other via pivot point  302  but are fixed in position via an extension adjustment rod  222 . As will be explained later, the angle between the first extension beam  218  and the second extension beam  220  can be adjusted by using the extension adjustment rod  222 . This mechanism can be used to adjust the sensitivity of the float mechanism. 
     The first extension beam  218  is contacted by the first inclined beam  208  at any point along its length. In an embodiment, the first extension beam  218  is contacted by the first inclined beam  208  at a point that lies between 10% and 50%, preferably 20% to 40% of the length of the first extension beam  218  measured from the end that contacts the second extension beam  220 . In an embodiment, the first extension beam  218  functions as a lever with its fulcrum point  306  located at the point of contact of the first inclined beam  208  with the first extension beam  218 . In an embodiment, the first extension beam  218  functions as a 2:1 lever with its fulcrum located at point  306 . The first extension beam  218  and the second extension beam  220  extend outwards and away from the first vertical bam  206 A of the main support mechanism. They extend radially outwards towards the outer periphery of the tank  230  and downwards towards the bottom of the tank  230 . 
     The second extension beam  220  extends from an end of the first extension beam  218  and contacts the float  224  at its (the second extension beam  220 ) opposing end. The first extension beam  218  and the second extension beam  220  are rotatably connected at a pivot point  302 . An angle α between the first extension beam  218  and the second extension beam  220  can be varied from 30 degrees to 180 degrees, preferably 50 to 150 degrees. 
     The extension adjustment rod  222  facilitates fixing the angle α between the first extension beam  218  and the second extension beam  220 . As may be seen in the  FIG.  3   , the extension adjust rod  222  has a plurality of ports  222 B,  222 C,  222 D and  222 E along its length (shown in the  FIG.  3   ) that can accommodate one or more protrusion(s) (see e.g.,  223  in  FIG.  2   ) present in either the first extension beam  218  or in the second extension beam  220  or in both the first extension beam  218  and in the second extension beam  220 . In an embodiment, one end of the extension adjustment rod  222  is rotatably pivoted off of either the first extension beam  218  or to the second extension beam  220 , while a port at the other opposing end (of the extension adjustment rod  222 ) is coupled to a protrusion located on the extension beam. In other words, if one end of the extension adjustment rod  222  is rotatably fixed to the first extension beam  218 , then the other end of the extension adjustment rod  222  will be coupled to a protrusion located on the second extension beam  220  and vice versa. 
     By using different ports  222 B,  222 C,  222 D and  222 E, the angle α between the first extension beam  218  and the second extension beam  220  can be varied. In the embodiment depicted in the  FIG.  3   , one end of the extension beam  220  is rotatably attached to the second extension beam  220  at  222 A, while the other end is fixedly attached to the first extension beam  218  at port  222 E. 
     This adjustable feature of extension adjustment rod  222  depicted in the  FIGS.  2  and  3    is useful for accommodating different sizes of pontoon tanks. The feature can also be used for accommodating tanks having different geometries. It may also be used to adjust the sensitivity of the float mechanism. 
     With reference now to  FIG.  2   , it is to be noted that the once a particular port (e.g.,  222 B,  222 C,  222 D or  222 E) is coupled with a particular protrusion on the first extension beam  218 , the angle α between the first extension beam  218  and the second extension beam  220  is fixed. In order to change the angle α between the first extension beam  218  and the second extension beam  220 , the port  222 B,  222 C,  222 D or  222 E is to be decoupled from the protrusion on the first extension beam  218  and a new port is to be coupled with the protrusion. This feature can also be used to let the float  224  travel up or down as desired. 
     The float  224  is preferably of a lower density than the fluid that collects in the tank and therefore floats atop the fluid. The float  224  may have any geometrical shape that provides it with a large surface area that can contact the fluid. In other words, its surface area is selected to be large enough so that it is sensitive to the presence of fluid and begins to become buoyant immediately upon being contacted by the fluid. 
     The float is preferably manufactured from a polymer that is insoluble in the fluid that it is to be buoyant in. The polymer is preferably a foamed organic polymer. Organic polymers may be selected from a wide variety of thermoplastic polymers, blend of thermoplastic polymers, thermosetting polymers, or blends of thermoplastic polymers with thermosetting polymers. The organic polymer may also be a blend of polymers, copolymers, terpolymers, or combinations comprising at least one of the foregoing organic polymers. The organic polymer can also be an oligomer, a homopolymer, a copolymer, a block copolymer, an alternating block copolymer, a random polymer, a random copolymer, a random block copolymer, a graft copolymer, a star block copolymer, a dendrimer, a polyelectrolyte (polymers that have some repeat groups that contain electrolytes), a polyampholyte (a polyelectrolyte having both cationic and anionic repeat groups), an ionomer, or the like, or a combination thereof. The organic polymers have number average molecular weights greater than 10,000 grams per mole, preferably greater than 20,000 g/mole and more preferably greater than 50,000 g/mole. 
     Examples of thermoplastic polymers that can be used in the polymeric material include polyacetals, polyacrylics, polycarbonates, polyalkyds, polystyrenes, polyolefins, polyesters, polyamides, poly aramids, polyamideimides, polyarylates, polyurethanes, epoxies, phenolics, silicones, polyarylsulfones, polyethersulfones, polyphenylene sulfides, polysulfones, polyimides, polyetherimides, polytetrafluoroethylenes, polyetherketones, polyether ether ketones, polyether ketone ketones, polybenzoxazoles, polyoxadiazoles, polybenzothiazinophenothiazines, polybenzothiazoles, polypyrazinoquinoxalines, polypyromellitimides, polyquinoxalines, polybenzimidazoles, polyoxindoles, polyoxoisoindolines, polydioxoisoindolines, polytriazines, polypyridazines, polypiperazines, polypyridines, polypiperidines, polytriazoles, polypyrazoles, polycarboranes, polyoxabicyclononanes, polydibenzofurans, polyphthalides, polyacetals, polyanhydrides, polyvinyl ethers, polyvinyl thioethers, polyvinyl alcohols, polyvinyl ketones, polyvinyl halides, polyvinyl nitriles, polyvinyl esters, polysulfonates, polysulfides, polythioesters, polysulfones, polysulfonamides, polyureas, polyphosphazenes, polysilazanes, polypropylenes, polyethylenes, polyethylene terephthalates, polyvinylidene fluorides, polysiloxanes, or the like, or a combination thereof. 
     The float can also be manufactured from a thermoset polymer (i.e., a crosslinked polymer). It is desirable for the polymer to be water insoluble. Polyolefins are preferred polymers for use in the float  224 . 
     The movable portion of the mechanism comprises a plurality of levers that communicate the presence of fluid (via buoyancy of the float) to the gauge rod  202 . The plurality of levers include a first lever  214 , a second lever  212 , a third lever  210  and a fourth lever  226 . A spring  236  contacts the first lever  214  at one end and the fixed frame at the opposite end. The spring  236  damps motion of the beam  218 . Each of the levers  214 ,  212 ,  210  and  226  contact each other via a rotatable pivot point that enable each of them to rotate with respect to each other. This will be discussed in detail later. The rotatable pivot point may be rivet, a bolt and nut combination or a screw. The rotatable pivot point may comprise a bearing that permits rotary motion about the pivot point if desired. 
     The first lever  214  is in contact with the end of the first extension beam  218  and preferably extends perpendicular to a longitudinal axis of the beam  218 . The first lever  214  contacts the first extension beam  218  at rotatable pivot point  218 A. The opposite end of the first lever  214  contacts one end of the second lever  212  at a rotatable pivot point  214 A, while the opposite end of the second lever  212  contacts the third lever  210  at a rotatable pivot point  212 A. It is to be noted that the second lever  212  and the third lever  210  contact the second inclined beam  216  at pivot point  212 A. 
     The opposite end of the third lever  210  contacts the fourth lever  226  at a rotatable pivot point  210 A, while the opposite end of the fourth lever  226  contacts the gauge rod  202  at pivot point  226 A. 
     As may be seen in the  FIG.  2   , the second lever  212  extends between the first lever  214  and the third lever  210 , while the third lever  210  extends between the second lever  212  and the fourth lever  226 . The fourth lever  226  extends between the third lever  210  and the gauge rod  202 . All of the levers—the first lever  214 , the second lever  212 , the third lever  210  and the fourth lever  226  can rotate with respect to each other. For example, when the float  224  begins to float as a result of the presence of fluid in tank  230 , the first extension rod  218  moves downwards causing an increase in the angle β between the second lever  212  and the third lever  210 . This is because the second lever  212  and the third lever  210  can rotate with respect to each other. There is also an increase in the angle γ between the third lever  210  and the fourth lever  226 , which causes the gauge rod  202  to move vertically through the passages in the horizontal beam  204  and the manway cover  232 . 
     The second lever  212  rotates clockwise about pivot point  214 A when the first extension rod  218  moves downwards (due to the upwards motion of the float  224 ). The clockwise rotation of the second lever  212  causes an anticlockwise rotation of the second inclined beam  216  about pivot point  304 . This causes anticlockwise rotation of the third lever  210  as well as the fourth lever  226 , which in turn promotes motion of the gauge rod  202 . 
     The gauge rod  202  contacts the manway cover  232  and the horizontal beam  204 . 
     The manway cover  232  and the horizontal beam  204  contain passages through which a gauge rod  202  can travel back and forth. The passage in the manway cover  232  is plugged with a seal (which also contains a passage)  234  through which the gauge rod  202  can travel back and forth. The seal  234  can be manufactured from a polymer, preferably an elastomer. 
     Suitable elastomers that are used in the seal are polybutadienes, polyisoprenes, styrene-butadiene rubber, poly(styrene)-block-poly(butadiene), poly(acrylonitrile)-block-poly(styrene)-block-poly(butadiene) (ABS), polychloroprenes, epichlorohydrin rubber, polyacrylic rubber, silicone elastomers (polysiloxanes), fluorosilicone elastomers, fluoroelastomers, perfluoroelastomers, polyether block amides (PEBA), chlorosulfonated polyethylene, ethylene propylene diene rubber (EPR), ethylene-vinyl acetate elastomers, or the like, or a combination thereof. 
     The levers, beams and rods generally comprise a light weight metal that does not undergo degradation in the presence of the fluid that accumulates in the tank. Suitable metals are aluminum, steel, copper, titanium, or alloys thereof. In an embodiment, the levers, beams and rods that constitute the float mechanism disclosed herein may also comprise the polymers listed above. 
     With reference now to the  FIGS.  2  and  3   , when fluid collects in the tank  230 , the float  204  becomes buoyant, which causes the first extension beam  218  to rotatably pivot about the first inclined beam  208  at pivot point  208 A. As the first extension beam  218  rotates about pivot point  208 A, it causes its downward motion to be transferred to gauge rod  202  via the first lever  214 , the second lever  212 , the third lever  210  and the fourth lever  226 . 
     The spring  236  serves to moderate motion of the mechanism. Rotary motion about pivot point  212 A and  210 A brought on by the downward motion of the first extension beam  218  causes levers  214 ,  212 ,  210  and  226  to rotate with respect to each other and to move the gauge rod vertically thus indicating the amount of fluid present in the tank  230 . 
       FIG.  4    depicts another embodiment of the float mechanism of the  FIG.  2   . In this mechanism the second lever  212  and the third lever  214  of the float mechanism are a joined together to form a single piece  502  (hereinafter the sixth lever  502 ), while the third lever  210  and the fourth lever  226  are joined to form a single piece  504  (hereinafter the seventh lever  504 ). A fifth lever  506  is rotatably pivoted between the sixth lever (at point  502 A) and the seventh lever (at point  504 A). 
     In the design depicted in the  FIG.  4   , the second inclined beam  216  is fixedly attached to the first inclined lever  208 . The main support mechanism in the  FIG.  4    thus comprises the first vertical beam  206 A and the second vertical  206 B, both of which contact the horizontal beam  204 . In addition to the beams  206 A,  206 B and  204 , the main support mechanism comprises the first inclined beam  208  that is fixedly attached to the first vertical beam  206 A and the second inclined beam  216  that is fixedly attached to the first inclined beam  208 . The design depicted in the  FIG.  4    differs from that in the  FIG.  2    in that the second inclined beam in the  FIG.  4    is fixed, while in the  FIG.  2   , it can rotatably pivot about point  304 . 
     The extension system of the  FIG.  4    is the same as that of the  FIG.  2   . In the interests of brevity, the extension system of  FIG.  4    will not be described any further. The reader can assess the function of this system by resorting to the information provided with regard to the  FIGS.  2  and  3   . 
     The movable portion of the float mechanism of the  FIG.  4    differs from that of the  FIG.  2    in that the second lever and a portion of the third lever are joined to form the sixth lever  502  while the remaining portion of the third lever and the fourth lever are joined to form the seventh lever  504 . The sixth lever and the seventh lever are not really lever number  6  and  7  respectively, but are so named to given them a different identifier from the previously named levers. The sixth and seventh levers are each L shaped (also described as boomerang shaped). The sixth lever  502  rotatably pivots about points  502 A,  502  B and  502 C respectively, while the seventh lever  504  rotatably pivots about points  504 A,  504  B and  504 C respectively. The angles β and γ between the respective arms of the sixth lever  502  and the seventh lever  504  can vary from 50 degrees to 150 degrees, preferably between 70 to 120 degrees. A fifth lever  506  is rotatably pivoted between the sixth lever  502  and the seventh lever  504  and contacts the sixth lever  502  and the seventh lever  504 . 
     As may be seen in the  FIG.  4   , the sixth lever  502  contacts the first lever  214  at pivot  502 A. It contacts the second inclined beam  216  at pivot point  502 B. It contacts the fifth lever  506  at pivot point  502 C. The opposite end of the fifth lever  506  contacts the seventh lever  504  at pivot point  504 A while the opposite end of the seventh lever  504  contacts the gauge rod  202  at pivot point  504 C. The seventh lever rotatably pivots about point  504 B on the vertical beam  206 A. A spring  236  contacts the vertical beam  206 B (or alternatively the horizontal beam  204 ) 
     With respect to the  FIG.  4   , when the water lever in the tank rises, the float  224  rises thus causing the first extension beam  218  to move downwards. This causers the sixth lever  502  to rotate clockwise about pivot point  502 B. This clockwise motion of the sixth lever  502  rotates the seventh lever  504  in the anticlockwise direction about pivot point  504 B, by virtue of the motion transmitted to it by the fifth lever  506 . The anticlockwise motion of the seventh lever  504  causes the gauge rod  202  to move vertically. Thus as the fluid level in the tank rises, the float  224  rises and in turn causes the gauge rod to move vertically. The displacement of the float is proportional to the displacement of the gauge rod. 
     As noted above, for the designs shown in the  FIGS.  2  through  4   , the displacement of the float is amplified. When the float is displaced by 1 inch, the gauge rod is displaced by at least 1.8 inches to 5 inches. The displacement ratio is also termed the leverage ratio as detailed above. For the design seen in the  FIG.  4   , the leverage ratio is at least 1:2 (i.e., for every 1 inch displacement of the float, the gauge rod is displaced at least 2 inches). 
     The design disclosed herein is suitable because it permits retrofitting old pontoon tanks with a new, more sensitive mechanism. This retrofitting can be accomplished without any significant alternation to the tank. In addition, the new design can be introduced into the pontoon tank and removed from it by a technician located outside the tank. This eliminates the possibility of danger to the technician who does not have to enter the tank and encounter potentially dangerous fumes. 
     This feature is depicted in the series of  FIGS.  5 A- 5 C , which show the float mechanism depicted in the  FIGS.  2  and  4    being installed and removed by installing and removing the manway cover respectively.  FIG.  5 A  depicts the manway cover with the mechanism installed in the pontoon tank  230 .  FIG.  5 B  depicts an initial step in the removal of the manway cover with the mechanism attached thereto.  FIG.  5 C  depicts another step in the removal of the manway cover with the mechanism attached thereto. In other words, the entire device can be removed and inserted into the tank via the opening  122  (see  FIGS.  1 ,  2  and  4   ). This design advantageously permits existing tanks to be retrofitted. 
     It is to be noted that the bottom of the tank can be inclined as seen in the  FIG.  1    or horizontal as seen in the  FIGS.  2  and  4   . There is no limitation on which tank bottom is used. For example, while the design in the  FIG.  1    has an inclined bottom, it can also have a horizontal flat bottom. The same logic applies to the tanks of the  FIGS.  2  and  4   . 
     While the invention has been described with reference to some embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.