US2849300A - Igniter - Google Patents

Description

ignition temperature.

United States Patent IGNITER Max George Berman and Arnold Irwin, Elkton, Md., and.

' Donald Walter K'ershner, Wilmington,

to Thiokol Chemical Corporation, corporationtof-Delaware No Drawing. Application. July 6, 1955- Serial No.. 520,354.

3 Claims. (Cl. 44-40) Dell, assignors Trenton, N. J'., a

The present invention relates to a'readilyignitable de vice capable of sustaining a flame for a time sufiicient to ignite a fuel such as wood, coal, charcoal briquets and mainder of the fuel. The difliculties involved in starting such fires is, of course, dependent to a considerable extent upon the conditions-towhich the fuel is exposed. Thus, if the fuel. is wet or moist, the amountof heat that is required must not only be sufiicient to raise the temperature of an appreciable portion of the: fuel to the.

ignition temperature, butmust also be sufficient to volatilize-the moisture.

In more modern applications it is also essential, e. g., when starting: a fire in an indoor fireplace, and certainly at least highly desirable even when starting a fire in an outdoor grill, that the operation be accomplished with a minimum generation of smoke, sparks and odor. Furthermore, in view of the messiness of handling such fuels as charcoal, it is imperative that the ignition of the fuel be successful on the. first attempt and that there be no necessity for rebuilding the fuel pile on top of the kindling material a second. time.

The present invention is addressed to overcoming these diificulties and to facilitating the ignition of fuels without generating undesirable smoke, sparks and-odors.

The device of the invention is an igniter having at least two components that are referred to herein and in the claims as a starter mix and a combustion-sustaining mix. It is the function of the starter mix, as the name implies, to ignite readily upon the application thereto ofa burning cigarette or cigar, or of the flame of a match, and to thereby elevate the temperature of part or all of the combustion-sustaining mix up to or beyond its It is the function of the combustion-sustaining mix, as the name likewise implies, to sustain a flame for a period of time amply sufficient to ignite an appreciable portion of the fuel packed around and above the device.

The starter mix is essentially a readily ignitable mixture of ammonium nitrate, carbon and of a burning rate accelerator such as potassium dichromate. If there is no objection to smoke, ferric oxide may be used as a burning rate accelerator. In an embodiment which gives satisfactory and dependable performance with little generation of smoke, the ammonium nitrate is present in an amount of about 82 to 85% by weight, the carbon is present in an amount of about to 12% by weight and is in the form of small particle sized wood charcoal 0r powdered charcoal, and the accelerator is potassium dichromate present in an amount of about 4 to 6%. Somewhat less favorable but still very desirable results are obtainable when the proportion of ammonium nitrate is as low as about or as high as about 92%, the carbon content is as low as about 8 or as high as about 20% and the proportion of potassium dichromate is as low as 3% or as high as about 10%. Potassium dichromate is preferred over ferric oxide because it is more effective in avoiding the formation of smoke. These desirable and preferred ranges, as well as maximum operable ranges of proportions of the ingredients in the starter mix are listed.immediately'below:

Operable, Desirable, Preferred, percent percent percent Ammonium nitrate 40-96 70-92 22-85 Carbon 2-40. 8-20 l0-l Burning rate accelerator 2-40 3-10 4- 6 if smoking is not objectionable, the proportion of. am-

monium nitrate may be considerably lower than even about 70% and the proportion of wax or other binder may be. as high as 50% or more. If sparking is not objectionable, the carbon content may be increased to as high as about 50%. When it is expected that ignition conditions will approach the ideal, as in hot, dry weather, the proportion of carbon may be reduced to below about 5%. Finally, ifbrittlenessof the igniter is not objectionable and. will not interfere withshelf life or transportability, the ammonium nitrate content may be as high as about 96% and the binder content may be below 3%.

It is highly desirable to obtain uniformly good results in terms of burning rate and possible effect thereon due to the hygroscopicity of ammonium nitrate, for the ammonium nitrate to have a particle size between about 10 and 50 mesh. Particle sizes between 12 and 30 mesh are preferred.

While parafiin wax is considered most desirable as the binding material, it is to be understood that other materials. are also suitable, particularly those which are combustible with a minimum of smoking and which are capable of binding. the granular ammonium. nitrate and carbon constituents together. Rosin, for example, is suitable as a binding material since a. sustaining mix formulated therewith.- can readily be ignited and its combustion readily becomes self-sustaining. It has the disadvantage however, as compared with paraffin wax, of producing considerable smoke varying from a dense white cloud to a fog.

In one useful embodiment of the invention, the starter mix and the combustion-sustaining mix are pressure packed into a paper cup and subsequently waterproofed by coating with parafiin wax. When so packaged, the fuel igniter devices are in a compact, sanitary and waterproof form that facilitates distribution, handling and use under all kinds of conditions. It is to be understood that the total weight of the two essential components in a given device will depend upon the ignition qualities of the fuel to be ignited and upon the conditions under which the ignition is to take place. Thus, for example,

Patented Aug. 26, 1953 it will readily be appreciated that if the intent is to ignite a hard coal that has been wetted down, the time the combustion-sustaining mix is required to burn on a self-sustaining basis must be considerably greater than if the intent is to ignite a pile of well dried and reasonably finely chopped wood. Generally speaking, a total weight of approximately 60 grams will suffice for most non-industrial purposes, such as outdoor charcoal grills and fireplaces. Since more than one unit may be employed, if that is considered desirable, it follows that the weight per unit is not critical.

The ratio of starter mix to combustion-sustaining mix may likewise vary widely, depending upon the type of fuel to be ignited, the conditions under which it is to be ignited and the shape of the igniter. Generally, it should be borne in mind that the starter mix need not ignite the entire combustion-sustaining mix at once, but merely a suificient portion thereof to bring it to the self-sustaining point. As a guide to those skilled in the art for determining a desirable ratio of starter mix to combustion supporting mix in any particular application, the combustion-sustaining mix should usually be present in a major proportion and the starter mix in a minor roportion. Another guiding principle useful particularly where the starter mix is adjacent a surface of combustion-sustaining mix having an area not in excess of a few square inches, is to provide approximately 1.4 to 2 grams of starter mix per square inch of said surface.

One desirable Way of manufacturing the igniter device of the invention is to place a pre-mixed amount of the starter mix, e. g., ammonium nitrate, charcoal and potassium dichromate, in a paper cup and to deposit a separately pre-mixed amount of the combustion-sustaining mix on top of it. The contents of the cup are then subjected to high pressure, e. g., of the order of 15,000 to 20,000 p. s. i. The pressed device is then capped and dipped in paraflfin wax, if desired, so as to make it im pervious to water.

Fuel igniter devices so made will ignite rapidly upon application thereto for a moment of a match flame or a burning cigarette or cigar. Upon being ignited the device will burn for approximately two or three minutes with a smokeless, yellow flame and will ignite from 12 to 15 charcoal briquets, or other fuels such as anthracite coal and wood. The unit is stable and resistant to shock. Temperatures as high as 170 F. do not appear to aifect its performance despite probable softening of its paratfin. As an example of its resistance to shock, the unit has been thrown a distance of 50 feet and nevertheless found to function with complete satisfaction thereafter.

Without in any way intending to limit the scope of the invention, the following example is set forth as the best mode now contemplated of carrying out the invention.

Example A starter mixture consisting of 6.7 grams ammonium nitrate, 0.9 gram of charcoal powder and 0.4 gram of potassium dichromate was deposited in a paper cup having a diameter of 2 /2 inches. 39.3 grams of ammonium nitrate and 3.2 grams of charcoal powder were then admixed with one another and finally with 2.7 grams of parafiin wax. The resulting combustion-sustaining mix was placed in the paper cup on top of the starter mix. A cap was placed on the paper cup and the whole was subjected to a pressure of 15,000 p. s. i., producing a unit having a diameter of 2 /2 inches and a thickness of approximately /2 inch. This unit was then dipped in molten parafiin wax.

The unit was placed in an outdoor grill and twelve charcoal briquets were piled around and on top of it. A lighted match was momentarily held so that the flame came into contact with the unit. It thereupon immediately ignited and, without evolving any substantial amount of smoke, ignited the charcoal briquets within a matter of two to three minutes.

It is to be understood that innumerable variations and modifications will readily occur to those skilled in the art upon reading this description. All such variations and modifications are intended to be included within the scope of the invention as defined in the accompanying claims.

We claim:

1. An igniter having two components in selectively combustible and contacting zones, one component being a starter mix and the other being a combustion-sustaining mix, the starter mix comprising a mixture of about 40 to 96% ammonium nitrate, about 2 to 40% carbon and about 2 to 40% of a burning rate accelerator selected from the group consisting of potassium dichromate and ferric oxide. the combustion-sustaining mix comprising a combustible mixture of ammonium nitrate, carbon and combustible binding agent.

2. An igniter having two components in selectively combustible and contacting zones, one component being a starter mix and the other being a combustion-sustaining mix, the starter mix comprising a mixture of about 82 to 85% ammonium nitrate, 10 to 12% charcoal and about 4 to 6% potassium dichromate and the combustionsustaining mix comprising a mixture of about 86% ammonium nitrate, 5 to 8% carbon and 3 to 6% paraffin wax.

3. An igniter having two components in selectively combustible and contacting zones, one component being a starter mix and the other being a combustion-sustaining mix, the starter mix comprising a mixture of about 82 to 85% ammonium nitrate, 10 to 12% charcoal and about 4 to 6% potassium dichromate and the combustionsustaining mix comprising a mixture of about 86% ammonium nitrate, 5 to 8% carbon and 3 to 6% paraflin wax, said components being pressure packed and dipped in parafiin wax.

7 References Cited in the tile of this patent UNITED STATES PATENTS

Claims (1)

1. AN IGNITER HAVING TWO COMPONENTS IN SELECTIVELY COMBUSTIBLE AND CONTACTING ZONES, ONE COMPONENT BEING A STARTER MIX AND THE OTHER BEING A COMBUSTION-SUSTAINING MIX, THE STARTER MIX COMPRISING A MIXTURE OF ABOUT 40 TO 96% AMMONIUM NITRATE, ABOUT 2 TO 40% CARBON AND ABOUT 2 TO 40% OF A BURNING RATE ACCELERATOR SELECTED FROM THE GROUP CONSISTING OF POTASSIUM DICHROMATE AND FERRIC OXIDE, THE COMBUSTION-SUSTAINING MIX COMPRISING A COMBUSTIBLE MIXTURE OF AMMONIUM NITRATE, CARBON AND COMBUSTIBLE BINDING AGENT.