Abstract:
A method of measuring a fluid level comprises providing a measuring device comprising a first material that changes appearance upon exposure to a first fluid, introducing the measuring device into a location comprising the first fluid and at least one other fluid, waiting for the first material to change appearance upon exposure to the first fluid, and withdrawing the measuring device from the location to determine the depth of the first fluid and the at least one other fluid. A measuring device for performing the method of measuring is also disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Application 61/057,463, filed May 30, 2008, the content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to measurement devices in general, and more particularly to a strip device for measuring the level of fluid in a contained environment. 
     BACKGROUND 
     There is a need to provide a simple and accurate method for field personnel in electric utilities to measure the dielectric fluid that may have leaked from underground high voltage transmission systems. Older underground transmissions systems that require dielectric fluid for cooling are manufactured in section lengths of approximately one thousand to two thousand feet. Special high voltage splices are used to join the sections together. Often these underground cable systems are buried under city streets and access to the splices are through manholes leading to underground containment vaults. 
     Containment vaults are large, typically ten feet wide by fifteen feet long by ten feet deep. Transmission systems of this type have sophisticated leak detection and upon being alerted to the possibility of a leak all the cable vaults are visually inspected by removal of the manhole covers in the street and looking into the vault to determine if there is an oil leak. Vaults typically contain rainwater and the presence of oil of any depth is difficult for field personnel to determine quickly. A sixteenth of an inch of oil/dielectric fluid looks the same as a foot. A wide variety of techniques are employed by utility technicians to determine the presence and level of oil within an enclosed vault. A wrong “guesstimate” could lead to costly site remediation where none may be required or worse, not initiating the proper response where it is required. 
     Many methods of measurement were researched for the purpose including level measurement floats designed to float in fluids with various specific gravities. Other electronic products used in geological applications were investigated as well. Both seem clumsy and or expensive. There is a need, therefore, for a measuring device that is simple to use, inexpensive to use and manufacture, and accurate in its measurement. 
     SUMMARY 
     A method of measuring the depth of an aqueous liquid underlying a hydrophobic liquid of lower specific gravity is disclosed and comprises providing a measuring device comprising a first material that changes appearance upon exposure to a first fluid, such as an aqueous fluid, introducing the measuring device into a location comprising the first fluid and at least one other fluid such as a hydrophobic fluid, waiting for the first material to change appearance upon exposure to the first fluid, and withdrawing the measuring device from the location to determine the depth of the first fluid and the at least one other fluid. A measuring device for performing the method of measuring is also disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates one embodiment of a measuring device of the present invention. 
         FIGS. 2A-2C  illustrate various embodiments of weighted sections of a measuring device. 
         FIGS. 3A-3C  illustrate a method of performing a measurement using the measuring device of the invention. 
         FIG. 4  illustrates a sample package including an embodiment of the device of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This disclosure describes the best mode or modes of practicing the invention as presently contemplated. This description is not intended to be understood in a limiting sense, but provides an example of the invention presented solely for illustrative purposes by reference to the accompanying drawings to advise one of ordinary skill in the art of the advantages and construction of the invention. In the various views of the drawings, like reference characters designate like or similar parts. 
       FIG. 1  illustrates a measuring device  100  preferably comprising a strip  100  of paper having a free end  110 , a first side  120  and a second side  130  opposite the first side  120 . The strip is preferably manufactured and provided in rolls of varying sizes in the nature of a tape reel, with the free end portion shown only here for purposes of convenience. For example, in one embodiment the strip of material might be supplied in rolls that are longer than five hundred feet. Perforations  140  may be provided at spaced apart locations to section the strip into discrete lengths as desired by the end user. Measurement indicators in the form of notches  150 ,  160  or the like are provided along the sides  120 ,  130  to assist in the measurement of a depth of fluid relative to the free end  110 , with such notches functioning like a ruler preferably with different scales on each side. Specifically, notches  150  along side  120  are provided, for example, at one-inch increments, while notches  160  along side  130  are provided, for example, at six-inch increments to provide a greater scale. While notches  150 ,  160  are shown, it will be appreciated that other measurement indicators could be used, such as simple printed markings as is known on a rule, for example, or other methods known in the art. In addition, while a strip of paper of certain dimensions is shown, it will be appreciated that carriers of other dimensions and configurations are contemplated. 
     The strip  100  is preferably coated or otherwise provided with a non-toxic material  170  that changes appearance or property in the presence of an aqueous fluid such as free or un-dissolved water. One example of such a material is a fluorescent dye that exhibits fluorescence upon exposure to aqueous fluid. A number of dyes will satisfy this functionality, although only certain dyes may be currently economically feasible in manufacture and use. Two non-limiting examples include fluorescein and rhodamine. For purposes of explanation, the present discussion will be limited to fluorescein, with the understanding that other materials are possible, and such material shall be referred to as coating  170 . Fluorescein is an orange-red powdered compound, molecular formula C 20 H 12 O 5 , that exhibits intense greenish-yellow fluorescence in alkaline solution. Its disodium salt is marketed under the trademark “Uranine,” and is also known as D&amp;C Yellow no. 8. Fluorescein is a fluorophore commonly used in dye tracing, and is also known as a color additive (D&amp;C Yellow no. 7). Fluorescein has an absorption maximum at 490 nm and emission maximum of 514 nm (in water). Also, fluorescein has an isoabsorptive point (equal absorption for all pH values) at 460 nm. One of its more recognizable uses was in the Chicago River, where fluorescein was the first substance used to dye the river green on St. Patrick&#39;s Day in 1962. Other uses of fluorescein include using it as a water-soluble dye added to rainwater in environmental testing simulations to aid in locating and analyzing any water leaks. Thus, initially, the strip  100  with coating  170  may appear to have an orange-red coloring on one or both sides of the strip  100 . 
     The free end  110  of the strip  100  is preferably weighted in some fashion so that the strip  100  can be lowered into a testing environment and held straight during use.  FIGS. 2A-2C  illustrate various non-limiting weighting options, such as a clip  200   a  or the like attached to the free end  110   a  ( FIG. 2A ), or a mass  200   b  attached to an eyelet  112   b  in the free end  110   b  ( FIG. 2B ), or a weighted section  200   c  integrally manufactured into the free end  110   c  ( FIG. 2C ). Other weighting options are contemplated. Also contemplated is a strip formed from a more rigid material that remains straight when held upright without any ancillary weights. A typical example of a mass  200   b  might be a two-ounce mass of metal such as copper, brass, steel, or an alloy of the same, for example. Other metallic and non-metallic weighting materials are contemplated. 
       FIGS. 3A-3C  illustrate one example or method of using the measuring strip  100  to determine the depth of an aqueous liquid  320 , such as free, un-dissolved water for example, underlying a hydrophobic liquid of lower specific gravity  310 , such as oil for example, in a contained environment  300  having a bottom  305 , such as an underground containment vault for example. While only two liquids are shown here, it will be understood that additional liquids could be present in a testing environment, such as additional layers of hydrophobic materials on top of an aqueous layer. For the purposes of measurement in deep vaults, for example, a ten foot length of strip material  100  might be selected. In order to insure the strip  100  would remain straight while being lowered into the vault  300 , a small weight  200   b  (see  FIG. 2B ) is attached to the free end  110 . For ease of use a small length of string  115  ( FIG. 3B ) is attached to the end opposite the free end  110 . The strip  100  is lowered into the vault  300  until the user feels the weight  200   b  touching the bottom  305  of the vault  300  ( FIG. 3B ). Insertion of the strip  100  into water  320  with oil  310  floating on top will initially coat the entire submerged portion of the strip  100  with oil  310  as it is passed through the oil  310  and into the water  320 . After about five seconds or the like, the coating  170 , which is preferably initially orange-red in color, will turn fluorescent yellow  330  after a sufficient time for the water  320  to penetrate the oil coating on the strip  100 . The oil  310  above the water  320  will soak into the strip  110  and merely darken the orange-red-colored strip portion  350  ( FIG. 3C ) and not fluoresce yellow giving a clear indication of the depth of the oil  350  relative to the depth of the water  340 . After the user removes the strip  100  ( FIG. 3C ) and inspects the same, the user will appreciate the depth of the water  340  as well as the depth of the oil  350  residing on top of the water in the vault  300  by counting the notches  150 ,  160  or with reference to other measurement guides as the case may be. 
       FIG. 4  illustrates one method of packaging a measurement device for commercial distribution comprising a package  400  including a coil of strip  100 , a desiccant  410  and preferably a weight  420 . Due to the reactive nature of the coating  170  applied to the strip  100 , the package is preferably purged with nitrogen to keep dry and hermetically sealed with a hot bar sealer or the like. Various coil lengths can be vended to address different applications. While one application has been shown and described where it is desired to have a ten-foot strip, for example, it will be appreciated that other applications are contemplated where it is desired to measure, for example, the depth of oil floating on water. One application is the quick inspection and measurement of oil in the hulls of ships. For this requirement, longer lengths of strip may be attached to a fixed or adjustable length pole or stick for insertion into a tank, in which case the coil strip might be much longer. Another may be for use by contractors in the field who may be working in an area that has pools of fluid containing water and oil and the presence and depth of oil may be required. For this application, short strips (nominally two-three feet) can be used for a quick measurement of the depth of oil or other hydrophobic media to aid in the determination of remediation required to remove the fluid. Additional lengths are also contemplated. 
     While the present invention has been described at some length and with some particularity with respect to the several described embodiments, it is not intended that it should be limited to any such particulars or embodiments or any particular embodiment, but it is to be construed with references to the appended claims so as to provide the broadest possible interpretation of such claims in view of the prior art and, therefore, to effectively encompass the intended scope of the invention. Furthermore, the foregoing describes the invention in terms of embodiments foreseen by the inventor for which an enabling description was available, notwithstanding that insubstantial modifications of the invention, not presently foreseen, may nonetheless represent equivalents thereto.