Liquid heaters and vaporizers – Stand boiler – Fluid fuel burner
Reexamination Certificate
2000-10-24
2002-09-10
Wilson, Gregory (Department: 3749)
Liquid heaters and vaporizers
Stand boiler
Fluid fuel burner
C122S013010, C122S497000
Reexamination Certificate
active
06446582
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to the extension of a gas feedline through a vapor barrier to interconnect a fuel source with the burner of a gas-burning appliance. More particularly, the invention pertains to a configuration that simplifies the installation of a gas feedline while establishing a seal between the gas line and the vapor barrier.
A potential hazard inherent in the operation of a gas-burning appliance is that it may cause flammable vapors to ignite that happen to collect in and around the appliance. Ignition may either be caused by the burner or pilot flame or by an electric or electronic ignitor upon being energized. This is especially problematic in for example water heaters or furnaces that are located in garages in which cars are parked where the leakage or spillage of gasoline may occur. Once a combustible mixture reaches the appliance, a fire or an explosion may result.
Efforts to address this potential safety hazard have been previously directed toward ensuring adequate ventilation in and around the appliance, the elevation of the appliance to distance it from flammable vapors that are denser than air, and more recently, the isolation or sealing of the combustion chamber from its surroundings. This latter approach not only prevents the incursion of vapors into the combustion chamber but also prevents the propagation of flame therefrom.
A difficulty associated with effectively sealing the combustion chamber of a typical gas-burning appliance is inherent in the necessity for various conduits to extend into the combustion chamber from the exterior of the appliance. The fitment of a sheet metal enclosure about the entire combustion chamber is typically relied upon to form a vapor barrier. The extension of any conduit through such barrier requires that an appropriate opening be formed in the barrier and that any gap between the installed conduit and the surrounding barrier material be substantially closed off. In the case of the extension of a gas feedline through such barrier, it is additionally necessary for there be some freedom of movement between the gas line and the barrier to facilitate installation. Moreover, only a minimal number of relatively inexpensive components which require only a minimal amount of labor to assemble should be required to provide an effectively sealed interface. The components associated with the sealing of the gap should be immune to deterioration during the service life of the appliance. Accordingly, the sealed interface must be capable of withstanding the elevated temperatures it is routinely subjected to due to its proximity to flame and must additionally be able to withstand even higher temperatures as may be mandated by various regulating agencies with regard to fire safety.
An approach that has previously been employed requires the use of a multi-piece feedline. A rigid length of feed line extending from an opening formed in the barrier inwardly toward the burner is first attached to the barrier such that a male fitting formed or attached to the proximal end of such length of feedline extends through such opening. A flange that is affixed to the fitting is staked to the outside surface of the barrier to form a seal. In order to impart the necessary flexibility to the assembly, a length of flex line is threaded onto the protruding fitting while its proximal end is threaded onto the gas controller/valve to complete the assembly. The multi-piece, multi-step assembly process is labor intensive and requires a number of rather expensive components. Additionally, every coupling is a potential source of leakage while the flex line is relatively fragile.
A mechanism is required that reduces the costs involved in the assembly of feedline to and through the vapor barrier of for example a water heater. A desirable configuration would require a minimal number of parts and a minimal amount of labor while nonetheless being capable of fulfilling the requirements with regard to maintaining the integrity of the seal established by the barrier.
SUMMARY OF THE INVENTION
The present invention overcomes the shortcomings of previous mechanisms that have been employed for extending a gas feedline through a vapor barrier while effectively preserving the integrity of the seal established by such barrier. This is achieved with the use of a minimal number of components while only a minimal amount of manual labor is required in their assembly.
The present invention employs a single rigid conduit for delivering a combustible gas from the gas controller valve to the burner. The conduit passes through an aperture in a flat metallic grommet that is crimped into place within a raised collar formed in a removable section of barrier material. The minimal clearance between the grommet and conduit precludes appreciable leakage there between while the contour of the inner edge of the grommet allows the conduit to be readily shifted and pivoted relative to the grommet to facilitate assembly and installation.
By employing a single rigid conduit to route gas from the controller valve to the burner, the total number of components that had previously been required is reduced including the elimination of a relatively expensive threaded coupling. Moreover, no assembly of multiple sections of conduit is required. The elimination of a coupling also serves to eliminate a potential source of leakage. Additionally, with the use of the grommet of the present invention configured to impart a degree of freedom of movement to the conduit, the need to use a length of expensive and less robust flex line is obviated.
These and other features and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment which, taken in conjunction with the accompanying drawings, illustrates by way of example the principles of the invention.
REFERENCES:
patent: 5099825 (1992-03-01), Massey et al.
patent: 5499621 (1996-03-01), Trihey
patent: 6109216 (2000-08-01), Reynolds et al.
patent: 6216643 (2001-04-01), Reynolds et al.
patent: 6244223 (2001-06-01), Welk
patent: 6269779 (2001-08-01), Overby. Jr.
Boehnlein Conrad
Duong Thach
Lewis Robert W.
Fulwider Patton Lee & Utecht
Robertshaw Controls Company
Wilson Gregory
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