Abstract:
A spark arrestor for a wood burning fireplace chimney. The spark arrestor of the present invention is mounted in the chimney, preferably proximate the damper.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention is directed to a spark arrestor for a wood burning fireplace chimney. The spark arrestor of the present invention is mounted in the chimney, preferably proximate the damper.  
           [0003]    2. General Background and State of the Art  
           [0004]    Wood burning fireplaces are a standard feature in many homes and cabins. Fireplaces generally include a damper, basically a valve plate mounted at the top of the firebox portion of the fireplace at the transition to the chimney, so that when the fireplace is not in use the damper may be closed so that a draft of outside air does not flow down the chimney and into the house or cabin. When the fireplace is to be used, the damper is opened to allow the hot combustion gases and byproducts to flow up through the chimney and exhaust to the atmosphere. Thus, the damper is generally pivotally mounted.  
           [0005]    In many areas having high fire risk, closely spaced houses or wood shingle roofing, building codes may require a spark arrestor to be include on the outlet of a chimney for every wood burning fireplace. These types of spark arrestors generally include a diverter or ducted exhaust structure or wire screen to reduce or eliminate the incidence of sparks exiting the chimney while still smoldering and possibly causing a fire hazard.  
           [0006]    However, wood burning fireplaces are not fully efficient combustors of wood, and it is common for carbon, soot, ash and other residues of the combustion process to be deposited on the internal surfaces of the chimney above the fireplace. The buildup of byproducts in the chimney may block the chimney, reduce the efficiency of the fireplace even further, cause the combustion gases to exit the fireplace through a front opening into the house as opposed to through the chimney and may cause a fire hazard in which the compounds adhered to the surface of the chimney combust. Spark arrestors located at the top of the chimney do not reduce or eliminate these types of buildups within the chimney.  
           [0007]    The spark arrestor of the present invention is intended to both eliminate the emissions of sparks from the chimney and reduce or minimize the buildup of byproducts within the chimney.  
         INVENTION SUMMARY  
         [0008]    The present invention contemplates a wire mesh spark arrestor, located proximate, designed into or mounted at a pivotal angle with respect to, the damper for the chimney. The wire mesh spark arrestor may have a design configuration matching the damper and may be mounted in a manner such that when the damper is opened the spark arrestor pivots into the position which the damper occupies when the damper is in the closed position. The spark arrestor can have a generally circular or disk shape, if that is the shape of the damper, or a square or rectangular shape if that is the shape of the damper. The spark arrestor is made from a wire mesh material which can withstand the hottest temperatures anticipated in the area above the fireplace leading to the chimney. Sparks and carbonaceous materials rising from the fire in the hearth of the fireplace contact the wire mesh and are either trapped until they burn off, or, if the mesh has been heated by the exhaust gases from the fireplace, to a sufficient temperature, the sparks, embers, ash and carbonaceous materials which come into contact with the mesh are combusted to their gaseous components. As a result, the spark arrestor may be self-cleaning whenever a sufficiently hot fire is obtained in the hearth. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a perspective view of a spark arrestor of the present invention attached to a circular damper mounted within a phantom depiction of a fireplace;  
         [0010]    [0010]FIG. 2 is a front view of the spark arrestor and damper of FIG. 1;  
         [0011]    [0011]FIG. 3 is a side view of the spark arrestor and damper of FIG. 1; and  
         [0012]    [0012]FIG. 4 is an alternative configuration of a spark arrestor assembly which can be mounted on a rectangular damper. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]    [0013]FIG. 1 is a perspective view of a phantom fireplace transition duct  10  having a disk shaped damper assembly  12  including a plate  14  mounted on a pivot rod  16 . The pivot rod  16  is suspended at its ends  18 ,  20  in openings  22 ,  24 , respectively, in the transition duct  10 . The plate  14  may also be connected to a lever arm  28 , which allows a user to rotate the plate  14  on the axis of the pivot rod  16  between an open and a closed position.  
         [0014]    A spark arrestor  30 , having two sections  32 ,  34 , which when combined generally match the shape of the plate  14 , is mounted at a ninety degree angle to the plate  14  on the pivot arm  16 , and affixed to opposite sides of the plate  14 . Each section  32 ,  34  of the spark arrestor  30  may have a rim  36  and a mesh section  38  as well as a mounting flange  40  to allow attachment to the plate  14 . The construction is further depicted in the front and side views of FIGS. 2 and 3, in which like elements are similarly numbered.  
         [0015]    The flanges  40  may be attached to the plate  14  by known fasteners, such as screws, bolts rivets and the like, or by magnets mounted on the flanges  40 . Magnetic mounting of the spark arrestor  30  would allow easy installation to existing iron plate dampers and also allow removal for cleaning if necessary.  
         [0016]    The mesh sections  38  are formed from a metallic mesh which has a sufficiently high melting point such that it would not be expected to melt or be oxidized in the combustion gas stream of the fireplace. A wire material formed from iron based alloy, steel, stainless steel, aluminum, or aluminum alloy materials, loosely interwoven and formed into a mesh, are examples of materials which would be adequate for use in forming the mesh. The mesh should be configured to allow the flow of combustion gases with minimal impediment, but provide a sufficiently tortuous path such that sparks, ash, soot and uncombusted carbonaceous materials would likely contact the mesh as the gases flow there through.  
         [0017]    In operation, when the plate  14  of the damper assembly  12  is rotated into the open position, the spark arrestor rotates into the operative position within the combustion flow path, as shown in FIG. 1. The hot combustion gases will heat the wire forming the mesh to an elevated temperature so that materials coming into contact with the heated mesh will be further combusted.  
         [0018]    [0018]FIG. 4 depicts a rectangular transition box segment  50  having a rectangular damper plate  52 , pivotally mounted on pivot rod  54 , and associated rectangular shaped spark arrestor  56 . The spark arrestor  56  includes a rim  58  and a wire mesh  60  attached by a flange  62  to the damper plate  52 , such that when the damper plate  52  is rotated to the open position the spark arrestor  56  rotates into the operative position.  
         [0019]    As will be appreciated from the foregoing, the spark arrestor of the present invention is designed to be operative with the damper and be mounted thereto. However, other configurations of the spark arrestor, mounted for example above or below the damper, are also contemplated upon an appreciation of the present invention. Further, embodiments, which due not include the rim or the flange sections only appropriately shaped wire mesh sections adhered to the damper plate, are contemplated. Accordingly, the present invention is to be defined by the appropriate scope of the appended claims.