EP3359907B1 - Non-pyrotechnic squib - Google Patents

Description

Field of the invention

The invention relates to igniters, flame generators and other devices for igniting an oxidizer for the combustion of objects. It relates in particular to the field of the dismantling of installations containing pyrotechnic waste to be destroyed. In particular, one thinks of a multitude of explosives in several different forms and states. Unconfined buildings, cassettes, asphalt mixes, pulverulent materials, machining slurries, detonators and explosive-laden waste may be mentioned. Waste contaminated with explosives, objects and materials comes in the form of materials, materials, personal protective equipment, tools, machines, solvents, most of the time contaminated with explosives encountered on the site.

Prior art and problem

A pyrotechnic waste destruction technique, currently in use, is to burn this waste in the open air. The smooth running of this burning operation begins with an essential step of initiating a combustion, that is to say causing ignition.

This ignition is done, most of the time, using devices called "pyrotechnic igniters". These initiator devices are, by definition, made up of two indispensable elements, which are a resistance and a pyrotechnic mixture, itself composed of a fuel and an oxidant. To form these can be used titanium, zirconium and potassium nitrate and potassium perchlorate.

A drop of the pyrotechnic mixture is deposited on the resistor, which is generally made of a thin metal wire and twisted. As soon as an electric current of sufficient intensity, at about 0.6 amperes, flows through the resistor for a given time, about 0.3 ms, the pyrotechnic mixture burns. This allows the start of the combustion of the material and allows the ignition of the oxidizer soaking the material to be destroyed.

This type of device is close to certain detonators, however, it differs in the sense that it does not function to produce a shock wave.

• transport des inflammateurs sur le site d'utilisation, avec soumission aux accords européens en vigueur, relatifs au transport international de marchandises dangereuses par la route ;
• mise en œuvre du dispositif sur le site, nécessitant la présence de personnel habilité et compétent ; et
• conditions de stockage et précautions lors de la manipulation des inflammateurs, par exemple pour éviter des chocs, des frictions et les éloigner de toute source de chaleur.

The pyrotechnic igniters use a pyrotechnic mixture and thus generates several problems which are the following ones:

• transport of igniters on the site of use, with submission to the European agreements in force, relating to the international carriage of dangerous goods by road;
• implementation of the device on the site, requiring the presence of authorized and competent personnel; and
• Storage conditions and precautions when handling igniters, for example to avoid shocks, friction and away from any source of heat.

In addition, the flame generated by such means, during the ignition of the oxidant, has a duration of only a few seconds. The operation is then delicate, when the weather conditions are unfavorable, for example in the presence of wind and / or rain.

• US 3 971 320 , montrant l'utilisation d'une enveloppe plastique métallique ou plastique ;
• US 4 380 958 et US 4 152 988 , montrant l'utilisation d'un agent d'enrobage ;
• US 10/947 975 , montrant l'utilisation d'une charge pyrotechnique.

Various pyrotechnic igniters are known from the following documents:

• US 3,971,320 , showing the use of a metal or plastic plastic wrap;
• US 4,380,958 and US 4,152,988 showing the use of a coating agent;
• US 10,947,975 , showing the use of a pyrotechnic charge.

On the other hand, by the patent US 7,363,860 a non-explosive initiator is known using a heating resistor in contact with a flammable mixture composed of metallic elements and a metal oxide, called "thermite". GB 345284 A , EP 14 34025 A1 and US 2012/180684 A1 constitute relevant documents of the state of the art.

The object of the invention is to avoid the disadvantages of the aforementioned devices, and the problems they pose and lower the cost of such devices.

Object of the invention

• un tube ouvert ;
• un morceau de laine d'acier placé dans le tube ouvert ;
• un fil sublimable sous une sollicitation électrique (dénommé communément « fil à éclat ») placé dans le morceau de laine d'acier ;
• un double cordon électrique connecté au fil mis dans la laine d'acier pour l'alimenter en électricité ;
• un tuyau d'arrivée d'air comprimé, débouchant à l'arrière du morceau de laine d'acier du même côté que le double cordon électrique ; et
• un disque placé du côté du tuyau d'arrivée d'air comprimé et du double cordon électrique, le disque maintenant en position ces deux derniers, le cordon électrique traversant le disque.

The main object of the invention is a destructible igniter, which mainly comprises:

• an open tube;
• a piece of steel wool placed in the open tube;
• a sublimable yarn under electrical stress (commonly referred to as "flash yarn") placed in the piece of steel wool;
• a double electric cord connected to the wire put in the steel wool to supply it with electricity;
• a compressed air inlet pipe, opening at the rear of the piece of steel wool on the same side as the double electric cord; and
• a disc placed on the side of the compressed air supply pipe and the double electrical cord, the disc holding these two last in position, the electrical cord passing through the disc.

Preferably, the tube and the disc are made of cardboard.

In a preferred embodiment, a foam cylinder placed against the disc, outside thereof, is used for the purpose of maintaining the dual electrical cord and the compressed air supply pipe. This allows the sealing of the inside of the tube at the disc. The disc also protects the foam cylinder from thermal radiation.

Preferably, it is advantageous to use a spacer placed in the open tube, between the piece of steel wool and the disc. The spacer allows to have reproducibility of manufacture of the igniter.

It is interesting that the double cord has two pods in which the ends of the sublimable wire are plugged, the pods being offset relative to each other not to be in contact with each other, once positioned in the piece of wool steel.

It is interesting to use a silicone tip on the end of the inlet pipe to facilitate the maintenance of the latter without tearing the inlet pipe relative to the disc.

List of Figures

• figure 1, en coupe, l'inflammateur selon l'invention ;
• figure 2, en vue cavalière, ce même inflammateur selon l'invention ;
• figure 3, en vue éclatée, l'inflammateur selon l'invention ;
• figure 4, en vue cavalière, le fil sublimable et son double cordon électrique d'alimentation ;
• figures 5A à 5F, les différentes étapes du montage de l'inflammateur selon l'invention.

The invention and its various technical features will be better understood on reading the following description, which is accompanied by three figures, respectively representing:

• figure 1 in section, the igniter according to the invention;
• figure 2 , in cavalier view, this same igniter according to the invention;
• figure 3 in an exploded view, the igniter according to the invention;
• figure 4 , in a cavalier view, the sublimable yarn and its double power cord;
• Figures 5A to 5F , the different stages of the assembly of the igniter according to the invention.

Detailed description of an embodiment of the invention

With reference to the figure 1 , the igniter according to the invention comprises mainly an open tube 1, inside which is placed a piece of steel wool 9, occupying the entire inner section of the open tube 1. Inside this piece of wool 9 steel, is placed a sublimable wire 8. This sublimable 8 wire is powered in electricity by a double electrical cord 6, which arrives at the piece of steel wool 9 and is equipped with two lugs, not shown in this figure.

On the left of the figure 1 , there is a disc 3 occupying the entire inner section of the open tube 1 and outside which is applied a foam cylinder 2. A spacer 10 placed inside the open tube 1 allows to hold spaced disc 3 of the piece of steel wool 9. The sublimable wire 8 may be made of stainless steel, for example Z8 CN 25 20 .

The disk 3 is made of cardboard, as is the open tube 10.

The disk 3 and the foam cylinder 2 are crossed at their center by a compressed air inlet pipe 4 which activates the combustion of the steel wool 9. It is completed with a nozzle 5 which surrounds it, preferably silicone and placed at the disc 3. This makes it possible not to tear the compressed air inlet pipe 4 of the disc 3.

A power cord runs along or passes through the foam cylinder 2 and runs along or through the disk 3. This double power cord 6 has its end positioned on the side of the piece of steel wool 9. The wire 8 is crimped on means of two lugs 7 to this electrical cord 6.

The figure 2 lets see this mounted set. It distinguishes the inlet pipe 4, the electric cord 6, the open tube 1 and a radial surface of the piece of steel wool 9.

The figure 3 lets you see all these pieces in an exploded way. It has included a lug 7 connecting the electrical cord 6 to the wire 8.

The figure 4 shows the connection of the wire 8 to the electrical cord 6, by means of two lugs 7. Each lug 7 is placed at the end of one of the two parts of the double electrical cord 6 and allows one end of the wire 8 to to be fixed. Note that the position of the two lugs 7 is shifted longitudinally, if we bring the two parts of the electrical cord 6. This is intended so that the two lugs 7 are not in contact with each other, once set to the inside of the piece of steel wool 9, the mounting does not necessarily ensure a precise and separate positioning of these two lugs 7. This avoids a risk of short circuit in the igniter.

The operating principle of the igniter is as follows. A current of sufficient intensity implodes the wire 8 sublimable. Thus, the piece of steel wool burns. The supply of compressed air through the inlet tube 4 makes it possible to maintain this combustion and the formation of an intense flame for a period of several minutes. Thus, the combustion of the materials inside the open tube 1 continues.

The composition of the whole of the igniter, partly in cardboard, allows its almost complete destruction at the end of the operation.

When using, simply connect the igniter to a power supply and a compressed air supply. The igniter is then placed in front of the waste to be destroyed. The opening of a service valve for supplying compressed air is then opened. The wire 8 is then energized. A voltage of 25 volts can be used at an intensity of between 10 and 20 amperes. The pressure of the compressed air to be sent inside the igniter can be of the order of 1 bar. Once these conditions are fulfilled, the firing can then take place.

The igniter according to the invention is easy to develop. The mounting principle is as follows.

With reference to the Figure 5A , a first phase is to crimp the wire 8 on the two pods 7.

With reference to the Figure 5B , the second operation is the establishment of the electrical cord 6 in the piece of steel wool 9, which has been precut.

With reference to the Figure 5C a third operation is to introduce this set into the open tube 1, which is preferably made of cardboard.

With reference to the figure 5D , the following operation consists of placing the open tube 10, which serves as a spacer, inside the open tube 1.

With reference to the figure 5E , the following operation is to prepare the inlet pipe 4 compressed air, equipped with a protective cap and mounted on the disc 3 and the foam disc 2.

With reference to the figure 5F , the last phase is to introduce this set prepared during the previous operation into the end of the open tube 1.

Advantage of the invention

The igniter according to the invention makes it possible to improve the temporal conditions of the burning of the waste. On the other hand, the igniter according to the invention is reliable, allows a remote firing and the generation of a flame for several minutes and can withstand the weather during use.

Claims (7)

1. A degradable squib,
   characterised in that it comprises:

   - an open tube (1);

   - a piece of steel wool (9) placed inside the open tube (1);

   - a sublimable wire (8) under an electrical bias placed in the piece of steel wool (9);

   - a double electrical cord (6) connected to the wire (8) to power the same and passing inside the open tube (1);

   - a compressed air inlet pipe (4) leading into the inside of the open tube (1), on the same side as the double electrical cord (6); and

   - a disc (3) placed on the whole section of the open tube (1) and passed through by the compressed air inlet pipe (4) and the double electrical cord (6).
2. The squib according to claim 1, characterised in that it comprises a foam cylinder (2) placed against the disc (3), outside the same to hold the double electrical cord (6) and the compressed air inlet pipe (4) and improve the sealing of the inside of the open tube (1) with respect to the disc (3).
3. The squib according to claim 1, characterised in that it comprises a spacer (10), placed in the open tube (1) and between the piece of steel wool (9) and the disc (3).
4. The squib according to claim 1, characterised in that the double power cord (6) has two lugs (7) into which the ends of the wire (8) are plugged in, the lugs (7) being offset from each other so as not to be in contact with each other when they are placed in the piece of steel wool (9).
5. The squib according to claim 1, characterised in that the open tube (1) is made of cardboard.
6. The squib according to claim 1, characterised in that the disc (3) is made of cardboard.
7. The squib according to claim 1, characterised in that it uses a silicone end cap (5), placed around the tube of the compressed air inlet pipe (4), at the disc (3) to hold the inlet pipe (4) without tearing the same off the disc (3).

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