Measuring and testing – Liquid level or depth gauge – Float
Reexamination Certificate
1999-06-28
2001-05-01
Williams, Hezron (Department: 2856)
Measuring and testing
Liquid level or depth gauge
Float
C073S307000, C073S321000, C073S322000, C073S322500, C073S29000R
Reexamination Certificate
active
06223596
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a liquid level indicator gauge, and more particularly to a portable gauge which can be conveniently and easily clamped onto a liquid storage tank for accurately determining the amount of liquid contained therein.
2. Description of the Prior Art
Liquid storage tanks are used to contain various substances in a wide range of applications. It is usually of interest, and often a necessity, to determine the level of liquid in a storage tank. Many approaches have been developed for determining liquid level. In most instances, the liquid level gauge is permanently installed on the storage tank. However, it is relatively expensive to provide a liquid level gauge in each storage tank when liquid level must be monitored in a plurality of such tanks. Furthermore, most liquid level gauges are not suitable for use as a portable device because of their intricate design, electrical connections, excessive weight, or bulkiness. Such gauges cannot be readily transported from one tank to another without undue risk of damage to the internal workings or delicate, external features of the device.
In some cases, rudimentary means are sufficient to determine liquid level, such as the insertion of a measuring rod or dip stick through an opening in the top of the storage tank. The measuring rod is typically graduated, with markings along its length which are indicative of the level of liquid contained in the tank. One end of the rod is initially placed in abutment against the bottom of the storage tank and the rod is then withdrawn. The liquid level is apprised by simply observing how much of the rod is wetted relative to the liquid level markings. However, various problems arise through the use of such a method to measure liquid depth. For example, certain volatile liquids, such as gasoline, tend to evaporate quickly so that the wetted portion of the rod may not be readily observable, especially in poor light. On the other hand, viscous liquids, such as diesel fuel or crude oil, are stable but are not easily wiped or removed from the measuring rod. Moreover, an accurate liquid level measurement is only possible if the measuring rod is manually aligned in a substantially vertical orientation.
More refined approaches for determining liquid level in a storage tank have been developed which utilize portable measuring devices. Such devices are disclosed in U.S. Pat. No. 3,691,839 to Lasher, and U.S. Pat. No. 4,819,484 to White. Although these devices are transportable, they do not have features which allow them to be easily and securely attached to the storage tank. Moreover, the liquid level reference point for these particular devices is the exterior top surface and interior bottom surface of the storage tank, respectively. However, in certain storage tank applications, such as a railroad tank car, the liquid level reference point is typically the interior top surface of the tank car.
The present invention attempts to remedy the problems and drawbacks of prior liquid level gauges, and provides a portable liquid level indicator gauge which easily and securely clamps onto a railroad tank car to accurately determine the amount of liquid contained therein relative to a predetermined liquid level reference point.
SUMMARY OF THE INVENTION
The present invention generally relates to a portable liquid level indicator gauge for easily and accurately determining the amount of liquid contained in a storage tank. While the nature of the invention covered herein is to be determined with reference to the claims appended hereto, certain forms of the invention that are characteristic of the preferred embodiment are described briefly as follows.
An apparatus and method are provided for indicating the amount of liquid contained in a tank having an interior surface defining a liquid level reference point. According to a typical embodiment, the gauge includes an elongate rod for indicating liquid level in the tank and a buoyant member operably connected to the rod to cause the rod to be vertically displaced in response to the vertical displacement of the buoyant member resulting from a corresponding change in liquid level. A guide defining a longitudinal axis slidably receives the rod and guides the rod generally in a longitudinal direction. A reference arm is operably connected to the guide and forms an abutting relationship with the interior surface of the tank at the liquid level reference point. In a further aspect of the invention, the portion of the reference arm forming the abutting relationship with the interior surface of the tank is located at a predetermined distance from a reference point on the guide.
It is an object of the present invention to provide an apparatus and method for accurately determining the amount of liquid contained in a storage tank relative to a predetermined liquid level reference point.
Another object of the present invention is to provide an easily and readily portable liquid level indicator gauge which is releasably attached to a portion of the storage tank. Additional objects, features, and advantages of the present invention will be apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.
REFERENCES:
patent: 2771774 (1956-11-01), Fornasieri
patent: 2772568 (1956-12-01), Samaritano
patent: 2807960 (1957-10-01), Schweitzer
patent: 2868016 (1959-01-01), Steed
patent: 3217541 (1965-11-01), Williamson
patent: 3283578 (1966-11-01), Moore
patent: 3359799 (1967-12-01), Lubin
patent: 3440880 (1969-04-01), Hoyer
patent: 3498141 (1970-03-01), Nelson et al.
patent: 3555905 (1971-01-01), George
patent: 3691839 (1972-09-01), Lasher
patent: 4019659 (1977-04-01), Deneen
patent: 4116062 (1978-09-01), Reip
patent: 4819484 (1989-04-01), White
patent: 5020367 (1991-06-01), White
patent: 6028521 (2000-02-01), Issachar
Electromechanical Research Laboratories Inc.
Loo Dennis
Williams Hezron
Woodard Emhardt Naughton Moriarty & McNett
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