Combustion – Flash-back controlling or preventing structure
Reexamination Certificate
2000-05-24
2001-09-18
Lazarus, Ira S. (Department: 3743)
Combustion
Flash-back controlling or preventing structure
C126S201000, C122S019200, C122S494000, C220S694100
Reexamination Certificate
active
06290490
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a protective covering for a gas-fueled appliance. In particular, the invention relates to a device for surrounding the lower periphery of an appliance such as a water heater, furnace or clothes dryer, to prevent spills on the floor from contacting the appliance and to contain any explosions or fires resulting from the ignition of fumes by the heater's gas flame.
2. The Prior Art
Natural gas-fueled water heaters have become very common in households, due to the efficiency and low cost of natural gas. One problem that has developed as a result of these water heaters, however, is the danger of fire and explosion from fumes and/or spills contacting the gas flames at the bottom of the water heater. These explosions and fires can cause substantial property damage, injury to household occupants, and even death. One proposed solution has been to elevate the water heater approximately 18 inches off of the floor. The drawbacks of this solution are that often there is insufficient headroom to elevate the heater in a small, low basement, or that the required revisions to the pipe system connected to the heater make the elevation unfeasible and too expensive. The fumes can also reach the heater when elevated when there is movement in the vicinity.
There have been attempts to construct shields to keep the fumes from spills from coming near the flame 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.
While these device are useful in preventing some explosions, they are not well equipped to handle all types of hazardous fumes.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to overcome the drawbacks of the prior art and to provide means for preventing explosions and fires resulting from the contact of all fumes or flammable liquids with the gas flames in water heaters, furnaces and clothes dryers.
It is another object of the invention to provide a means for preventing such fires and explosions without moving or changing the configuration of the water heater.
It is yet another object of the present invention to provide a means for preventing such fires and explosions that is easy to assemble, inexpensive and removable.
These and other objects and features of the present invention are accomplished by a flash suppressor for surrounding a gas-fired appliance, comprising a barrier that forms an enclosure around a lower portion of the appliance. The barrier 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 inside wall has a plurality of ventilation holes located 25% down from the top to allow the heat currents to enter the space. There is a filter disposed in the space for filtering fumes from outside the outside wall to prevent the fumes from reaching the appliance and igniting from a spark from the appliance. The inside wall is preferably a thin piece of aluminum and the outside wall is preferably a thicker piece of steel.
Typically, the appliance is a hot water heater, a gas furnace or a clothes dryer. If the appliance to be protected is a hot water heater, the barrier is round. If the appliance is a furnace or dryer, the barrier will be rectangular, to follow the shape of the appliance.
There is an outwardly extending flange surrounding a top edge of the barrier. The flange has an inside wall connected to the inside wall of the barrier, an outside wall connected to the outside wall of the barrier, and a space between the inside and outside walls that communicates with the space in the barrier. The flange is made of steel and has an open top, so that fumes travel through the filter by way of air currents caused by the heat given off by the water heater and out the open top and are thus kept away from the flame in the appliance. The flange having the open top is made of thicker steel to cool the fumes as they exit. The outward direction of the flange directs the filtered fumes away from the appliance. Preferably, the flange extends about 2½ inches out from the outside wall of the flash suppressor.
In use, the temperature difference between the thin aluminum inner wall and the thicker steel outer wall and flange causes a thermal air draft inside the flash suppressor, causing air to be sucked in from the outside and out through the opening in the flange. The series of ventilation holes in the thin aluminum inner wall allow the thermal currents to enter, causing a siphoning effect, which help suck the fumes through the filter. The se holes also allow for the currents to carry back out any fumes that may enter over the top.
The flash suppressor preferably has a base for supporting the barrier on the floor. The base has a flat bottom and two side walls that contact the inside and outside walls of the barrier to keep the barrier in place. This is particularly important if the barrier is made of two or more pieces that fit together to surround the appliance.
The filter is preferably a removable panel that contains activated granular carbon. The activated carbon removes 80-90% of the hydrocarbons from the fumes that could ignite when in contact with a spark from the appliance. The filter should be changed every year to prevent excess solids buildup and should be changed after every fume-creating spill near the flash suppressor.
To accommodate the filter between the inside and outside walls, the outside wall has a lower portion and an upper portion, with the lower portion being larger in circumference the upper portion. The outer wall has a horizontally oriented channel between the upper portion and lower portion to permit insertion and removal of the filter. The channel preferably has a cap removably positioned over it.
Preferably, the barrier is about eighteen inches in height and together with the flange measures about 20 inches in height. The filter is preferably about 12 inches in height. The width of the flash suppressor depends on the size of the appliance to be surrounded. Ideally, there is about a 3 inch gap between the appliance and the inside wall of the barrier all around. For example, if a water heater is 19 inches in width, the barrier would have an inside diameter of 25 inches. The space between the inside walls and the outside walls of the upper portion, 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.
The barrier is preferably made of at least two pieces that fit together around the appliance. The barrier is preferably made of galvanized steel. The ends of each piece are preferably capped. In this embodiment, the filter is also divided into at least two sections to fit within each piece of the barrier. Alternatively, the flash suppressor could be built integrally with a water heater, furnace or dryer, and be permanently attached thereto.
To maintain the width of the space between the inside and outside walls, 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.
There is preferably a cover surrounding the flash suppressor and having exhaust and inlet openings to allow the fumes to be filtered.
The present invention is simple to manufacture and successfully prevents ignition of fumes that occur near a gasfired appliance. It can be easily installed around existing appliances with no modifi
Cocks Josiah C.
Collard & Roe P.C.
Lazarus Ira S.
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