US2010862A - Spark arrester - Google Patents

Description

Aug. 13, 1935.

J. 'A. JOHNSON SPARK ARRESIER Filed June 4 1 1934 2 Sheets-Sheet l Inventor K Johnson 5 al-mm Attorneys 1935- J. A. JOHNSON I 2,010,862

SPARK ARRESTER Filed June 4, 1954 2 Sheets-Sheet 2 Inventor I John A-Johnaon I Attorney;

Patented Aug. 13, 1935 UNITED STATES PATENTJIOFFICE John A. Johnson, Crawfordsville, Ind., assignor to National Supply & Service Corporation, (Draw-'- fordsville, Ind.

Application June 4, 1934, Serial No. 728,925 14 Claims. (o1. 1's3 9s) This invention relates to the art of spark arresters adapted to be placed over thetops of fiues or chimneys. v 1

In forming a spark arrester, it is necessary that any device applied to the flue must not interfere with the normal draft. encountered, particularly as applied to residence or low draft flues, has been that the devices would become clogged with soot or lined with paper scraps and at times with snow and sleet, so that eventually, the flue draft would be so seriously reduced as to require the removal of the device. The problem, therefore, in eliminating the 'fire hazard arising from soot burning in the flueand from trash burning, is to provide some structure that will retain burning masses untileither consumed, extinguished, orbr'okenup into small particles and that will not cause a reduction of the draft in the flue by the filling in or the covering over of the structure by such masses.

It is a primary object of my invention to provide means for arresting thefdischarge of burning particles issuing from a flue until the particles are consumed or broken up into small masses less than that normally required to ignite woodQfAn important object of the invention is not'only to arrest such burning particles as above indicated,

but to breakup the larger particles andallow the smaller particles to escape without clogging up the device to a point aifecting the flue draft.

A further important object of my invention is to provide means automatically closing certain openings in the spark screen toward whichQparti- 016s of ignited matter may be blown by wind so that such matter will be retained during the presence of high winds until they have been consumed orbroken up into inconsequential particles. In supplying this automatic means, it. is the object of the invention to have such means operative only in the presenceof high winds and even .then a to close only those openings on the lee side so as to leave openings uncovered on the windward side. i

A further important object of the invention is to provide a series of openings in the wall of the screen graduated fromsmall sizes toward the base to larger sizes in the upper part of the wall.

A still further important object of myinvention is to provide a total effective outlet opening approximately that of the flue cross-section regardless of the amount of soot and the like leaving theilue. Other objects and advantages such as the extreme simplicity and relative low cost of production, willbecome apparent in the following A difiiculty heretofore I form a foraminous receptacle with the base entirely open, the receptacle" here being'shown and made from woven wire in the nature of hardware cloth as itis popularlyknown. .It is mm in the one particular form as rectangular in shape particularly noted that for a distance upwardly from the lower edge of the receptacle, the transverse or horizontally disposed wires are spaced 7 closer together than they are thereabove. Preferably this close spacing extends approximately up from the base for one-third of the total'height of the receptacle.

p The receptacle is provided with a plurality of openings through the wall, here 'shownas one horizontally disposed openingin each of the four walls, the openings being designated by the mi: merals Ill, ll, l2 and I3. Each of these openings is here shown as being at the same elevation and is formed by horizontally cutting through the vertically disposed wires to form a slit there-' through and further by cutting vertical slits in effect by cutting horiontal wires at the ends of the horizontal slit whereby the wall may be bent inwardly above the slit'and also below the slit to form inwardly projectingflanges l4 and i5 integralwith the wall. It is tops; noted that the slit i's made in each instance about midway between the adjacent horizontal wires or vertical wires in either case so that projecting ends of the wires areleft to'form spikes along the inwardly turned flanges. 13y means of this formationiof theopenings, 'it is to "be observed that the openings'are in eifect spaced inwardly from the'pla'nes of the respective walls and that-the under flange l5 slopes upwardly toward that opening whilethe upper flange l4 slopes downdownturned edges of this flange it then define a rectangular opening into the receptacle from the top.

7 I form a closure ll which in cross section is in the form of a V. This closure is brought up against the under sides of the marginal edges of the flange l6 and there attached to underlap those edges so that the raw edges of the trough closure I! are presented or directed upwardly. This closure H is madeof a foraminous material, preferably as herein shown, a woven wire of square mesh. The mesh of this material employed in the closure ii is selected to have larger openings therethrough than are had in the upper portion of the side wall of the recep-- tacle proper. It is to be noted, however, that since the closure ii is trough-like in nature and has its apex hanging downwardly from the top of the receptacle, the effective openings through the closure ii in a vertical direction do not exseed the actual openings through the side walls.

Referring again to the longitudinal openings through the side walls as represented by the numerals Hi, El, l2 and E3, the total combined area of these openings is preferably made to be approximately equal that of the flue or stack to which the screen is to be applied. This combined area is therefore sufficient to take care of the normal draft through the stack should the screen reach its maximum possible clogged position wherein all of the perforations become clogged through one cause or another.

As an added factor of safety, particularly in such localities where high winds may prevail at certain seasons when the flue or stack is most liableto give off burning embers or particles of matter, I add a swinging bafiie i3, Fig. 2 which is in effect an inverted wire basket although the material is not necessarily limited to wire since any foraminous material would serve the purpose. Preferably the edges of the baiiie l8 slope outwardly from the major base portion so that the edges are presented angularly in reference to the base. The bafiie is employed in an inverted position to have those edges sloping downwardly and outwardly and on the base of the baffle in this inverted position, I place and secure vanes l9 and 20, one at right. angles to the other so that the one vane l9 extends upwardly from. the longitudinal center line of the bafiie while the other vane 2i? extends upwardly from the transverse center line, the two vanes intersecting one another. The baffle it with these vanes attached is swung within the receptacle by means of wire links 2| and 22 which are swingably connected to the closure H at its apex. The dimensions of the bafiie #8 are selected to be such that when the bafile I8 is hanging in its normal central position as indicated in Fig. 1, there is an appreciable opening or clearance between the marginal edges of the baflle and the wall of the receptacle. This opening may be varied clepending upon the degree .of wind which is desired to swing the baffleto its closing position. When the receptacle is mounted on the top of the flue or stack to which it is, to be'einployed, the baffle 18 when the wind pressure becomes suflicient against the vanes l9 and 20 will swing the baflie against the lee side of the receptacle and the lengths of the links 24 and 22 are so proportioned that in this swinging action under the wind pressure, the marginal edges of the baffle will come up under the respective flange or flanges l so as to cause the bafiie to prevent passage of any particles between the baiiie and the side wall of the receptacle on the lee side thereof. Thus the upcoming particles would strike against the underneath side of the bafile l8 and could not escape directly out through the horizontally disposed opening, H}, H, 12 or 53 as the case may be. However an increased opening is then provided on the windward side of the baflle :8, between the marginal edge of the baifle and the wall of the receptacle so that there would be no interference of the normal draft in any event and regardless of the condition of the side wall of the receptacle. Of course as soon as r the wind pressure decreased, the baffle would an tornatically return to its normally, centrally disposed position.

In some cases it would be entirely desirable'to dispense with the closure l! where the baffle i8 is employed, in which case the links 2i and 22 would be secured to the inturned marginal edges of the flange it.

In the normal operation of the spark screen, the ignited particles which are to be controlled would tend to rise vertically within the receptaole. Thus particles moving upwardly along the inside of the receptacle wall would be deflected inwardly upon striking the under flange M at each of the horizontal openings, the actual contact therewith tending to break up those particles into smaller ones. Thus particles which would rise on past and strike the marginal flange it would have the choice of two directions. In one case the particles would be directed around to fall down along the inner side of the receptacle to drop onto the top flange Hi over each of the horizontal openings so that the particles would be deflected inwardly. In the other case the particles would tend to fall around in the direction of the inturned end of the flange it and would strike the raw edge of the closure ii in some instances and in others pass on down thereunder. Of course any projection, particularly in a roughened state, especially when presented as spikes tends to break the particles in smaller units of less dangerous consideration. These particles rising through the center of the receptacle, where the baffle 58 is not employed, and these particles would normally constitute the major quantity, strike the trough-like closure l! which tends to spread the particles outwardly toward the side wall of the receptacle. The angularity of the closure l? on either side thereof is such that as the particles strike thereagainst and move therealong, a more or less grinding and cornminuting action is produced so as to reduce the particles in size as well as to delay their movement so as to permit a longer period of burning within the receptacle. Of course some of these particles may pass on through the perforations of the closure II but when they do so they are of such reduced size as to be nonhazardousin respect to igniting shingles on a roof adjacent the stack.

Now when these particles roll on up the sides of the closure ll and strike the flange it, they are of course deflected around and down again within the receptacle and by reason of the flange Hi, tend to be directed back into the central upwardly moving current of the gases coming from the stack.

This operation has been described wherein lit e or no wind prevails across the top of the stack. Now when there is a wind, which existsmost of the time, the particles will tend to be carried toward one side of the receptacle but the operation above indicated will be followed. If there smaller high velocity particles.

' and a baffle swingably carried within the wall ing particles.

be a high wind, immediately the particles escape from the top of the chimney, they are carried against the opposite wall of the receptacle with some force'and tendto adhere to that opposite wall. The area against which these particles strike is then generally limited to the lowermost portion of the wall and it is-for this reason that the openings are reduced in size as compared'to the openings in the upper portion of the wall. The introduction of the baiiie I8 within the receptacle as a further factor of safety gives'the operation in addition as above indicated.

" The variation in sizes of openings in the receptacle walls is an important feature in the structure. When the wind isstrongest, the burning matter is swept almost entirely horizontally across the top of the chimney'against the side wall of the receptacle. Therefore, the openings in the side wall within that height covering the path of such wind swept matter are reduced to that size wherein the matter passing on through is harmless, and at "the same time, the openings thereabove are larger so as to preserve the desirable passages under low or no wind condi tions, it being kept in mind, that under. the high Wind conditions, the sparks arehotter and smaller immediately they leave the chimney, than when they ascend verticallyin the absence'of w nd. The larger openings will arrest the cooler and larger particles which reach them, whereas the smaller openings will arrest the hotter and The faster laterally moving particles require smaller openings to stop'them than do the slower vertically movotherwise would escape laterally from the receptacle under high speed conditions reach the dang'erzoneof the roof quicker and ma much hotter condition than do the vertically ascending particles which would travel into the air vertically some distance and then descend, giving a time element for cooling of the particles before the roof is reached. l

While I have herein shown and described my invention in the best form as now known to me,

it is obvious thatstructural changesmay be made therefrom, such, for example as in the materials employed to form the parts of the receptacle, proportions, and relative sizes of. open- 1 ings, without departing from the spirit of the invention, and I, thereforefdo not desire to be limited to thatpreciseform beyond the limitations as may be imposed by the following claims.

I claim:

1. For a chimney, a spark arrester comprising a foraminous walled extension above the chimney, and a baiiie swingably carried within the wall subjected to being rocked by'winds to reduce the opening between the bafile and the wall on the lee side and havingan area less than the horizontal cross-sectional area of the extension.

2. Fora chimney, a spark arrester comprising a foraminous walled extension above the chimney,

area less than the horizontal cross-sectional area of the extension, and a fo-raminous top across the extension, the perforations in the top at least in tion to the perforations thereof, and having perforations of less size immediately above the chim- Moreover, those particles which ney than in the upper portion of the wall whereby particles of matter driven laterally by wind will tend to be retained in smaller sizes than those normally ascending to the upper wall portion, a top across said wall formed to extend'arcuately around therefrom and down therewithin to have a' V shape thereacross with its apex directed downwardly. l l V 4. For arresting matter escaping from a chimney, a foraminous wall forming in effect an extension of the chimney, said Wall having horizontally disposed openings therethrough in addition to the perforations thereof, and havingperforations of less size immediately above the chimney thanin the upper portion of the wall whereby particles of matter driven laterally by wind will tend to be retained in smaller sizesthan those normally ascending to the upper wall portion, a top across said well formed to extend arcua'tely around therefromand down therewithin to have a V shape thereacross with its apex directed downwardly, said top being foraminous, and at least said V shaped portion of the top having larger openings therethrough than are in said wall.

5. For a chimney, a spark arrester comprising means for retaining sparks of a size normally arising from the chimney, and means for retaining smaller sparks swept laterally from the chimney under wind pressure, and means at the top of said smaller spark retaining means automatically shiftable by the wind for arresting rising of the sparks in the arrester above a predetermined level and preservng the normal draft of the chimney.

6. For aresting matter escaping-from a' chimney, a single foraminous wall forming in effect an extension of the chimney and having perforations of less size immediately above the chimney than in the upper portion of the wall whereby particles of matter driven laterally by wind will tend to be retained in smaller sizes than those normally ascending to the upper wall portion, a baflle swingably mounted within the wall, and vanes,

on the bafile' subject to wind pressureto shift the baffle to the leeside of the wall to have the baflle substantially'cut off a direct path from the chimneyto the upper part of the wall.

7. For arrestingmatter escaping from a chimney, a foraminous wall forming in effect an extension of the chimney, said wall having horizon-- tally disposed openings therethrough in addition to the perforations thereof, and having perfora tions of less size immediately above the chimney than in the upper portion of thewall whereby particles of matter driven laterally by wind will tend to be retained in smaller sizes than those normally ascending to the upper wall portion,a bafile swingvanes on the baffle subject to wind pressure to shift the baffle to the lee side of the wall to have the'bafile substantially cut off a direct path from the chimney through the lee opening, said baffle having less area than thatof, the passage formed from the chimney by the wall whereby normally a passageway is afforded around the baffle into the upper space within the wall above the baflie.

.8. For arresting matter escaping from achimney, a foraminous wall forming in eifect an extension of the chimney, said wall havinghorizontally disposed openings therethrough in addition to the perforations thereof, and having perforations of less size immediately above the chimney than in the upper portion of the wall whereby particles of matter driven laterally by wind will tendbaffle to swing by wind toward the lee side of the wall.

' 9. For arresting matter escaping from a chimney, a foraminous wall forming in effect an extension of the chimney, said wall having horizontally disposed openings therethrough in addition to the perforations thereof, and having perforations of less size immediately above the chimney than in the upper portion of the wall whereby particles of matter driven laterally by wind will tend to be retained in smaller sizes than those normally ascending to the upper wall portion, a top across said wall fonned to extend arcuatel around therefrom down therewithin to have a V shape thereacross with its apex directed downwardly, a bafile of less area than the passageway defined by said wall, means rockably suspending the baflle from said top, and vanes on the baffle to cause the bafile to swing by wind toward the lee side of the wall, said baffle being suspended below said horizontal openings.

10. For arresting matter escaping from a. chimney, a foraminous wall forming in effect an extension of the chimney, said wall having horizontally disposed openings therethrough in addition to the perforations thereof, and having perforations of less size immediately above the chimney than in the upper portion of the wall whereby particles of matter driven laterally by wind will tend to be retained in smaller sizes than those normally ascending to the upper wall portion. a

. top across said wall formed to extend arcuately around therefrom and down therewithin to have a V shape thereacross with its apex directed downwardly, a baffle of less area than the passageway defined by said wall, means rockably suspending the baffle from said top, and vanes on the bafile to cause the bafile to swing by wind toward the lee side of the wall, said baffle being suspended below said horizontal openings, an inwardly extending flange across the under side of said horizontal openings substantially at the upper level of said smaller sized perforations.

11. For arresting matter escaping from a chimney, a foraminous wall forming in effect a vertical extension of the chimney, said wall having perforations of less size toward the chimney end than that of the perforations toward the upper end, and having openings therethrough addition to said perforations, inwardly directing flanges above and below said openings, and a foraminous top extending downwardly within the wall, said top having at least a sloping portion thereof provided with perforations larger in size than those in the wall.

12. For arresting matter escaping from a chimney, a foraminous wall forming in effect a vertical extension of the chimney, said wall having perforations of less size toward the chimney end than that of the perforations toward the upper end, and having openings therethrough in addition to said perforations, inwardly directing flanges above and below said openings, and a foraminous top extending downwardly within the wall, said top having at least a sloping portion thereof provided with perforations larger in size than those in the wall, said top being in effect a V-shaped trough dropped within the upper end of said wall, and said wall being curved around inwardly and downwardly to meet the trough.

13. For arresting matter escaping from a chimney, a foraminous wall forming in effect a vertical extension of the chimney, said wall having perforations of less size toward the chimney end than that of the perforations toward the upper end,

and having openings therethrough in addition to said perforations, inwardly directing flanges above and below said openings, and a foraminous top extending downwardly within the wall, said top having at least a sloping portion thereof pro-v vided with perforations larger in size than those in the wall, said top. being in effect a V-shaped trough dropped within the upper end of said wall, and said wall being curved around inwardly and downwardly to meet the trough, and a baffle swung from the trough within the wall to be normally below said openings, and means carried by the balile to cause it to swing under wind pressure.

14. A spark arrester for chimneys and the like comprising a pair of elements, one within and spaced from the other and each having slotted openings, the slots of one element extending at right angles relative to the slots of the other element, said inner element being hung on said outer element for swinging movement relative thereto.

JOHN A. JOHNSON.

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