US3734790A - Gaseous illuminant pyrotechnic systems - Google Patents

Abstract

A HOMOGENEOUS PYROTECHNIC SYSTEM WHICH MAY BE USED FOR PRODUCING INTENSE ILLUMINATION SUCH AS THAT GENERATED BY FLARES. THE SYSTEM FUNCTIONS BY REACTING AN ALL-GASEOUS FUEL, OXIDIZER AND BORON ADDITIVE TO PRODUCE AN INTENSE FLAME.

Description

Patented May 22, 1973 United States Patent Ofice 3,734,790 GASEOUS ILLUMINANT PYROTECHNIC SYSTEMS Abraham D. Kirsheubaum, Succasunna, and Francis R. Taylor, Mount Arlington, N.J., assiguors to the United States of America as represented by the Secretary of the Army No Drawing. Filed ct.22, 1970, Ser. No. 83,210 Int. C1. (3061 15/00 U.S. Cl. 149-22 7 Claims ABSTRACT OF THE DISCLOSURE A homogeneous pyrotechnic system which may be used for producing intense illumination such as that generated by flares. The system functions by reacting an all-gaseous guel, oxidizer and boron additive to produce an intense ame.

The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

. BACKGROUND OF THE INVENTION This invention relates to a homogeneous pyrotechnic system for use in making flares of variable intensity, burning rate and 'magnification.

Prior high altitude pyrotechnic systems were composed of mixtures of finely divided metal fuels and inorganic oxidants in a solid state.

The solid systems were made by blending the ingredients of desired particle size with approximately 5-10% of organic binder in an appropriate solvent. The resulting mixture was loaded in increments under pressure into paper, plastic or metal tubes. These flares were then cured and dried under controlled conditions.

In the past these systems exhibited variable burning performance characteristics due to particle size, homogeneity, loading pressure, voids and case material. Also, once initiated, the burning process could not be stopped.

Excess metalin the flare which was vaporized in the burning process'and subsequently burned in air to produce additional light, remained unburned at high altitudes due to a lack of'oxygen.

g The subject invention, the use of an all gaseous system for flares, which operates by contacting a gaseous fuel, oxidizer, and boron additive, overcomes all the disadvantages of the prior art heretofore described.

Reproducible homogeneous mixtures are readily obtained, the system can be turned on and off at will, and illumination levels and burning times can be varied by increasing and decreasing the gaseous flow rate and flow time of the various gases.

Further, these all-gaseous systems do not require atmospheric oxygen and can be used at both high and low temperatures thus providing a high altitude capability.

. Finally, all-gaseous systems produce flames relatively free of particulate matter and consequently radiation from these flares can be magnified and directed by appropriate reflectors.

It is, therefore,.an object of this invention to provide a homogeneous pyrotechnic systemsuperior to prior flare systems.

Another object is; to provide a pyrotechnic system which exhibits increased luminosity when compared to prior fiare systems. 7

A further object is to provide a pyrotechnic system which can function at high altitudes and low temperatures.

Yet another object is to provide a pyrotechnic system which produces radiation responsive to reflection and magnification.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same become better understood from the following detailed description.

I A system has now been discovered that consists of a gaseous fuel, gaseous oxidizer and gaseous boron additive. It was found that if certain gaseous boron compounds such as boron trifluoride (3B,) or diborane (B H were passed into high temperature gaseous flames such as hydrogen-oxygen difloride or hydrogen-oxygenflorine, a very bright light was obtained.

Various studies were made using different gaseous systems as radiation sources. Tests ran using a gaseous fuel of H and an oxidizer of 0 show, upon the addition of BF that a maximum light output of only 3880 candleseconds per gram was attained. It was later discovered that by going to higher temperature flames greater light outputs were obtained. As a result H OF and H -O -F flames with high flame temperatures were found to be ideal systems.

Two types of burners were used in studying various gaseous systems. Concentric tube and perforated ring-tube burners were used to measure the light output of H -OF BE; and H O F -BF flames. A perforated ring-tube burner was used to study the light output of H --OF -B H flames since plugging due to thermal decomposition occurred when the diborane system was used in the concentric tube burner. I

A calibrated Weston photovoltaic cell, Model 856 Y Y V with viscor filter, was used in the following light output experiments.

Example I.--H O'F -BF system TABLE I.LIGHT OUTPUT OF Hz-OFz-BFz FLAMES Conditions Volume Candlepercent seconds] Hz/OFz BFs gram The use of a polished aluminum'parabolic mirrorwith the system producing 14,410 candleseconds/gram directionally increased the output 12 fold to 170,000 candleseconds/ gram.

Example 11 Varying amounts of 0 were added to a H F -BF flame having different H -F ratios. A summaryof these results is presented in Table H.

A H OF gaseous system was ignited in a perforated ring tube burner. The mixture in a ratio of 2 parts fuel to 1 part oxidizer exhibited a light output of less than 20 candleseconds/ grams. When a 4.4 vol. percent of boron trifluoride (BF was added, the light output increased to 22,500 candleseconds. The use of a parabolic reflector system further increased the directional output to 240,000 candleseconds/ gram.

Example IV A H OF gaseous system was ignited in a perforated ring-tube burner. The mixture in a ratio of 3 parts fuel to 2 parts oxidizer exhibited a light output of less than 20 candleseconds/gram. When a 4 vol. percent of diborane (B H was added, the light output increased to 43,200 candleseconds/gram.

Example V A gaseous system of methane (CH oxygen difloride (P and boron trifluoride (BF was studied and the results shown in Table III.

TABLE III.--LIGHT OUTPUT OF CH4OF:-BF3 FLAMES Volume Candlepercent seconds] OFz/CH4 BF gram Example VI 4 Gaseous systems of acetylene (C Hz), oxygen (0 or oxygen difluoride (0P and boron trifluoride (BF were also tested. The results for the various ratios are shown in Table IV.

TABLE IV.LIGHT OUTPUT OF CzHa FLAMES Oxid- Volume Candleizer/ percent, seconds/ System 0 11 BF; gram C H 0 BF 1.02: 2.8 3,850 a r T- a 1.50:1 2.9 6,650 2. 07:1 3. 7, 250 2.54:1 4.3 7, 840 3.18:1 3.9 7,150 4. 45:1 3. 1 5, 850 1. 00:1 0 4, 000

C H OF BF 1.00:1 1.5 4,500 a r 2- a 1.61:1 2.0 8,350 2. 03: 1 3. 2 5, 800 1. 00:1 0 6, 000

It is evident from the mixtures and results set forth in Examples I, H, III, IV, V and VI that the introduction of gaseous boron additives to a gaseous fuel-oxyfluoride system greatly increases the' light output of the system.

When boron additives are added in the amount of 4.2- 6.5 vol. percent to gaseous H OF mixtures having various ratios of 1:1 to 3:1, an increase from 20 candleseconds/gram to between 7,000 and 22,500 candleseconds/gram was obtained.

In a H O F system of varying ratios (Ill-1.84:1 Hg/Fz) and (0.260.99:1 og/Fg) the addition of a boron additive in the range of 2.5-4.7 vol. percent increased the light output from 20 candleseconds/gram to between 12,000 to 15,250 candleseconds/gram.

Further, with the addition of a reflector system to the light emitting system, the directed light output can again be increased, e.g. H -OF -BF (22,500 candleseconds/ gram) plus a reflector yielded 240,000 candleseconds/ gram. The use of a reflector system is made possible by the lack of smoke and particulate matter produced by the ignition and combustion of the system.

In the gaseous systems which employ methane and acetylene as fuels, the light output is again increased but not as substantially as the hydrogen systems. This is due in part to the buildup of unoxidized carbon on the burner tip.

This invention provides a novel flare system having a simple, all gaseous, efficient, fuel-oxidizer-additive system. No atmospheric oxygen is required; therefore, this invention operates as efliciently at high altitudes as it does at sea level.

The system eliminates the variable performance characteristics of older flare technology. It also provides a method for controlling the amount of radiation by simply adjusting the gaseous flow.

This system also provides a capability for stopping and restarting the radiation.

Finally, the system provides superior luminosity when the boron additive is incorporated in the system.

It is evident that other selected gaseous compounds can be used in place of the specific fuels, oxidizers and additives mentioned to achieve the same effect when in-- corporated into the system of our invention.

We wish it to be understood that we do not desire to be limited to the exact details described for obvious modi fication will occur to a person skilled in the art.

We claim:

1. An all gaseous system for use in flares comprising: a gaseous fuel selected from the group consisting of hydrogen (H and an aliphatic hydrocarbon, a gaseous oxidizer selected from the group consisting of oxygen difluoride (0P and a mixture of oxygen and fluorine (O /F and a gaseous boron additive selected from the group consisting of boron trifluoride (BF and diborane 2. The system of claim 1 wherein said gaseous fuel is hydrogen (H 3- The system of claim 1 wherein said gaseous boron additive is boron trifluoride (BF;,).

4. The system of claim 1 wherein said gaseous boron additive is diborane (B H 5. The system of claim 1 wherein the gaseous fuel is an aliphatic hydrocarbon.

6. The system of claim 1 wherein the aliphatic hydrocarbon is selected from the group consisting of methane (CH and acetylene (C H 7. The system of claim 1 wherein the gaseous boron additive does not exceed about 6.5% by volume.

References Cited UNITED STATES PATENTS 3,030,423 4/1962 Alley et al. 149--22X 3,092,664 6/1963 Clark et al. 14922X 3,135,802 16/ 1964 Kendrick III et al. 149-22 X 3,159,681 12/1964 Stange et al 14922X 3,203,979 8/1965 Ager, Jr. et al. 149-22X 3,293,303 12/1966 Lawton et a1 149-22 X CARL D. QUARFORTH, Primary Examiner P. A. NELSON, Assistant Examiner U.S. Cl. X.R.