Liquid heaters and vaporizers – Stand boiler – And casing feature for stand boiler or external water tank...
Reexamination Certificate
2002-03-21
2003-06-17
Lu, Jiping (Department: 3749)
Liquid heaters and vaporizers
Stand boiler
And casing feature for stand boiler or external water tank...
C122S494000, C122S504000, C122S044200, C122S155200
Reexamination Certificate
active
06578531
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a natural gas appliance such as a water heater having a protective device built into the lower periphery of the unit, to prevent vapors from spills of flammable liquids from contacting the ignition source of the appliance.
2. The Prior Art
There are more than 50 million homes in the United states that heat their domestic water with conventional gas fired water heaters. Although these units are very efficient and cost effective, there is an opportunity to improve on the design to completely eliminate a potential source of infernos and explosions in the event of an accidental flammable liquid spill in the vicinity of the water heater.
The extent of this devastation is alarming. There are over two thousand such accidents each year in this country, causing hundreds of personal injuries and dozens of fatalities. Most of the deaths are young children who are innocently unaware of the danger. In addition, there are tens of millions of dollars in property damage each year, with hundreds of the victims sustaining total losses. Combined, there is a total societal cost topping half a billion dollars per year due to the current design.
There have been attempts to construct shields to keep the vapors from spills from coming near the flames of the water heater. One such device is disclosed in U.S. Pat. No. 5,918,591 to Vollmar et al. This device comprises a mounting strip and a shield mounted in the mounting strip to surround the water heater. The strip and shield are made of plastic. Another such device is shown in U.S. Pat. No. 5,967,138 to Cacace. This device comprises an aluminum collar that is held in place by two rings to hold it in place. A further design is shown in U.S. Pat. Nos. 6,290,490 and 6,309,209 to Cacace, the disclosures of which are herein incorporated by reference, which also disclose a flash suppressor applied to existing appliances that prevents vapors from coming near the flames of the appliance.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to overcome the drawbacks of the prior art and to provide a water heater having a built-in means for preventing explosions and fires resulting from the contact of all fumes of flammable liquids with the gas flames in the heater.
These and other objects and features of the present invention are accomplished by a water heater having a flash suppressor which comprises a barrier that forms an enclosure around a lower portion of the heater. The heater comprises a water tank and a steel skirt having a bottom and a side wall for slidably receiving the skirt. The skirt is approximately fourteen inches high and has apertures for allowing air to enter the combustion chamber. The apertures are preferably {fraction (1/16)} perforated holes that allow air to enter but not exit from the combustion chamber. There is a flue and baffle in the center of the water heater that rests on the combustion chamber. There is a burner affixed to the bottom of the skirt for heating water in the water tank. Gas is fed to the burner assembly, which in turn heats the water in the tank. A thermostat controls this process. In use, the tank is slid into the skirt so that it rests on top of the burner.
The barrier is attached to and surrounds the skirt and has an inside wall, an outside wall and a space between the inside and outside walls. The outside wall has at least one aperture for air to pass into the space. The aperture is preferably located in the bottom portion of the outside wall. The outside wall is preferably 11¾ inches high. The inside wall is preferably located approximately ¼ inch away from the outside wall and 1 inch away from the skirt wall. The inside wall is preferably approximately 12 inches high. Vapors enter the space between the inside and outside walls through the aperture in the outside wall and are then pulled through this space and exit out of the top.
The inside wall has a plurality of ventilation “vortex” holes disposed in three rows located approximately two inches from the top to allow the heat currents to enter the space. The top row of holes are one sixteenth of an inch triangular perforations one inch apart. The center row of holes start one inch below the top row and are one sixteenth of an inch triangular perforations spaced ½ inch apart. The final row of holes begin one inch below the center row and are one sixteenth of an inch triangular perforations spaced one inch apart and are staggered from the top row. All perforated holes face the outside wall. This process draws air in the outer aperture by way of air currents created by the energy the appliance gives off The currents enter the “vortex” through the fresh air intake and cause a siphoning effect to the inside and outside walls. The inside and outside walls create a spout on top that extends away from the appliance at a 45 degree angle. The spout is at least one inch in length and is an extension of the inside and outside walls.
The entire device is preferably constructed of thin-gauged rolled steel and the inside wall is preferably made of aluminum. This allows the inside wall to heat up warmer than the outer walls to help the air currents rise. This process has proven to be extremely effective during tests.
There is a filter disposed in the space between the lower inside and lower outside walls or in the aperture of the outside wall to help break down the fumes while they are channeled through the flash suppressor. The filter can be made up of activated carbon. The activated granules attract the hydrocarbons in the vapors as they pass through the filter. These filters must be changed after every accident as they “fill up” with flammable hydrocarbons.
Alternatively, the filter can be a screen made of a FeCrAlloy® material, which is an iron/chromium alloy, that is coated with a hydrocarbon-based catalyst. This catalyst will “burn” off hydrocarbons and render them harmless. The catalyst must be heated to become active. This is accomplished by a plurality of heat radiating rods extending radially from the burner to the side wall of the skirt. The rods are made of stainless steel alloy and help to equalize the heat within the combustion chamber so that noxious gases. from the burner are burned off. The rods are covered with a ceramic sleeve for insulation. The rods are attached to the screen. The combustion chamber heats the rods, which in turn heat the screen to become active. This process works well as long as the burner is on and not in an idled position. The rods are also preferably coated with a catalyst for best results.
A third alternative for a filter is a screen formed from a material comprised of “Sol-gel” which is an organic polymer sorbent that has affinities for wider variety of analytes than does the carbon based sorbents. Organic polymer sorbents usually have lower thermal stability limits. The Sol-gel is formed into a screen to fit the aperture in the outer wall and acts a s a filter to remove the harmful hydrocarbons. The Sol-gel does not need to be cleaned, refreshed or changed.
The space between the skirt and the inside wall is about 1 inch, and the space between the inside walls and the outside walls of the upper portion, and between the filter and inside wall is preferably about ½ inch, which allows sufficient air flow through the barrier without it being too thick or too thin to cause the air draft to be too strong or too weak. If the draft is too strong, the filter may not work efficiently. If the draft is too weak, the current cannot draw the fumes fast enough to work properly.
To maintain the width of the spaces, there are a plurality of vertical ribs disposed between the inside and outside walls. Alternatively, other types of spacers or supports could also be used.
By having a controlled vertical process and a reverse vertical process in the same channel, we are creating a reciprocating movement throughout the channel. This movement causes a centrifical motion within the channel, or a vortex ring. This vortex ring r
Collard & Roe P.C.
Lu Jiping
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