First Fire Mixtures

In Formula 197, sulfur is replaced with 5% Laminae 4116, with catalyst added 

The compositions of typical igniter, first fire, and starter mixtures are also given in Table 5-29, p 5-48 of Ref 54. This Table is reproduced here as Table I  

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Napalm will keep well if stored in a tightly sealed container. It can be ignited with a match or any of the first fire mixtures described previously. The ignition packet should be placed adjacent to or just over the napalm, otherwise the petroleum may soak it and prevent its burning. 

A good source of ready-made thermate is the U.S. military AN M-14 Incendiary Grenade. To remove the thermate, first pry out the fuse assembly with crimpers or other nonsparking implement. See Figure 61. The reddish-brown caked substance on top of the contents of the grenade is a first fire mixture and it is spark sensitive. This should be broken up and the grayish powder beneath, which is the thermate, can be poured out. 

When used with highly compacted main pyrotechnic items, such as flare candles the "first fire" is either pressed (in dry form), or painted (in paste or slurry form) on top of item. For initiation of solid proplnts, a "first fire " mixt can be ignited if confined in a tube or capsule so that the hot gases will be spread over a larger surface area (Ref 57, pp 189 91) Table F lists various formulations for "starter mixtures" Table G for "ignition mixtures" and Table H for "first fire mixtures". -These formulations are given in Ref 57, pp 377-83. Some mixtures are taken from Ref 44a,... 

When the bomb strikes the target, inertia causes the firing pin to move forward striking the primer. The primer ignites the "first fire mixture" which ignites the filler (1) (0.63-lb of Thermate, TH3) and the Mg alloy body (2)... 

M. D. Banus J. J. McSharry, USP 2688575 (1954) CA 48, 14210 (1954) specify that Ti powder for use in first-fire mixtures for incendiary bombs or shells should... 

Because the ignition of the aluminum in flash bulbs requires a powerful igniter mixture, special first-fire mixtures containing zirconium and potassium perchlorate have been developed and are reported in the literature. ... 

The theory of initiation has mainly been expounded in the field of solid-propellant ignition. A recent effort for pyrotechnics has been published by Johnson.The calculations are difficult since they involve calories transferred to the surface of the initiated column at certain temperatures and over a time interval heat absorption and flow in the main item, heat developed in the main item from the incipient final reaction, and, of course, heat losses. Johnson advocates on the basis of theoretical considerations a small area on which lire transfer is concentrated low thermal conductivity, density, and specific heat of the first fire and use of high-energy, flare-type first fire mixtures in such a way that radiant heat transfer is optimal. 

Since initiation may take place at high altitude, fire transfer may be impeded by the changes in burning rate or flame temperature caused by diminished atmospheric pressure. This can be counteracted if the fire transfer takes place in full confinement or under adequately obturated conditions. Also, certain first fire mixtures, as shown below, are less influenced by pressure changes than others. 

To return now to practical measurements of heat of reaction, it is djvious that for experimental determination, one need only enclose the reactants in a calorimetric bomb, initiate the reaction, and measure (as described briefly above) the amount of heat released. One complication is that for a rather inert system, the customary electrically heated wire loop, which requires only a trifling correction, must be enhanced by a first fire mixture, thus reducing precision even if corrections are applied. Some mixtures may be entirely unreactive in the small amounts accommodated in the standard calorimeters. Undoubtedly, everyone concerned with these problems has had some ideas on designing a 55 gallon drum type calorimeter with or without admission of external air, but the author is not aware of any pub-Nshed experimentation along these lines. 

This loose powder mixture, scaled in a plastic bag together with a transfer line such as the end of a length of delay fuse (the latter provided with some adhering first-fire mixture at its flash end) is a safe, cool-burning starter for such items as mixtures of paper and nitrate for document destruction. 

Engineers at CWS strengthened the fuze to withstand harder impacts, replaced metal vent plugs with cork, and developed a better first fire mixture. The improved bomb, AN-M50A2, slightly lighter and thinner than its predecessor, functioned well. As fast as the new munitions came from plants they were shipped to Europe and used. The earlier model remained in reserve until 1944 when it was discarded. ... 

A slower-burning mixture is preferred over a more rapid one. The slower release of energy allows for better heat transfer to the main composition. Also, most "first fires" are pressed into place or added as moist pastes (that harden on drying), rather than used as faster-burning loose powders. 

Potassium nitrate is frequently used in igniters and first fires. Compositions made with this oxidizer tend to have low ignition temperatures (typically below 500 C), and yet the mixtures are reasonably safe to prepare, use in production, and store. Potassium chlorate formulations also tend to have low ignition temperatures, but they are considerably more sensitive (and hazardous). ... 

Compositions with high ignition temperatures (i.e., above 600°C) can be difficult to ignite using solely the "spit" from a black powder fuse or similar mild ignition stimulus. In such situations, an initial charge of a more-readily-ignitible material, called a "first fire," is frequently used. The requirements for such a mixture include [ 3] ... 

First-Fire Composition. It is usually a mechanical mixture of an illuminating compn with BkPdr, as was defined under item 3. However, for certain items, it may be a special composition which is nonhygroscopic, easily ignitable mixture with high-burning temperature (Ref 37, p 6)... 

Pyrocore, manufd by DuPont Co. It consists of metal tubing 1/8 inch or less in diam filled with combined explosive and ignition mixture, 4-40 grains per foot. It is claimed that even coarse commercial Thermite can be initiated from Pyrocore if Alclo Pellets (A1 35, K perchlorate 64 vegetable oil 1%) are used as a starter or as a first fire (Ref 57, p 191 and "Explosives Specialty Manual" E.I. duPont de Nemours, Wilmington, Delaware. ( Not listed in alphabetical Index of Ref 50)... 

The oldest and still widely used in pyrotechnics and fireworks "first fire" and "starter" mixture is BkPdr. It belongs to mixts without metallic ingredients. Metallic mixts contain combustible powdered metals, such as Mg, Al, Zr etc. Metalloids B and Si are considered metallic fuels because of their similarity in pyrochemical behavior to metals. Although BkPdrs are described in Vol 2 of Encycl, pp Bl65ff, we are giving here as Table E compns of three formulations used in pyrotechnics, as described by Ellern (Ref 57, p 375)... 

It may be mentioned that the same mixtures that are employed as first fires "(See Table H), may also have certain applications in "heat-producing cartridges" or "delay trains Conversely, a "delay"or a "heat powder" mixture... 

First Fire, Ignition end Starter Mixtures Used in Pyrotechnics such as defined in Dr Ellem s book are listed in Vol 4, pp D763 to D767 and in Tables F, G, H and I... 

First fire, igniter and starter mixtures used in pyrots 4 D763—D767 6 F38... 

Pyrotechnic mixtures which are used for ignition in blasting caps or detonators or which are used as first fires in propellant charges, are very easy to initiate. Here the initiator generates a flame if it is hit with a metal (percussion primer) or if it is initiated electrically using resistance heating (bridge wire). The first fire then initi-... 

With the exception of the hand grenade, type AN-M8, which contains 19 oz of HC mixture (2 min B.T.) and is thrown, HC-smoke munitions belong to the largest of the strictly pyrotechnic munitions. The Ml Smoke Pot (ffC) contains lO lb, the M5 Smoke Pot HC) 301b of composition in addition, they can be stacked for multiplication of the 5—20 min of smoke emission. First fires for the HC-smokes will be discussed in Chapter 23. 

The specific functions that fall into this category are first fires and igniters for pyrotechnic mixtures and solid propellants fire transfer... 

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