Squib

The primary safety considerations in the formulation, manufacture, and use of explosives are that they must never explode prematurely but always explode when desired. Often this balance is achieved with an insensitive main charge being initiated by the least amount of a more sensitive explosive. This concept is expanded to that of an explosive train in which a series of decreas-ingly sensitive explosives is ultimately sufficient to initiate an insensitive main charge. The sensitivity of explosives to initiation provides a common means of classification  

Other explosives may be added to explosive trains to sensitize certain components or add a time delay. There are as many combinations as necessary to 

Mercury fulminate detonators were widely replaced due to their extreme sensitivity. Contemporary simple nonelectric detonators contain a small quantity of primary explosive (often lead azide) which, once ignited by a fuse, ignites the more powerful base charge of a secondary explosive (an additional low explosive may be used between the fuse and the primary explosive). 

Often another controlled volume of low explosive is placed between the matchhead and the primary charge. This bums for a specified period introducing a delay (from a few milliseconds to a few seconds) into the detonator. However, any low explosive delay device syn. delay electric igniter) introduces imprecision because the chemicals are affected by moisture, temperature, and time. High precision delay electric detonators implant the match-head directly into the primary explosive and control the delay with an integrated circuit within the detonator. 

Detonators for ammunition include primary explosives to detonate the main charge. They may or may not be co inected to a fuze. 

---

Reactor depressurization (for GDCS operation) is provided by six squib depressurization valves. 

Miner s Squib (PSjtard de Mineurs). One of the primitive devices which was invented by Daddow in Engl in 1874 for igniting blasting expls. It consists of a tapered paper tube, about 7 inches long, filled with fine gunpowd. One end of the tube is filled with chemicals, such as milled gunpowd mixed with either sulfur or sulfur and charcoal, so as to form a sort of slow match. 

A little gunpowd is added at the end in order to facilitate ign of the slow match. When used, the squib is inserted with the slow match outward in a hole made in a charge of BkPdr blasting expl. When the match is lit, the fire burns slowly, allowing the miner time to reach a place of safety. As soon as the fire reaches the BkPdr core of the squib, it burns fiercely and then suddenly explodes, igniting the blasting expl. Instead of the paper tube, quills filled with fine BkPdr joined to a slow match, can be used... 

Hunter (Ref 1, p 379) proposed, in 1882, a squib which resembled that of Daddow, except that the tube contg the BkPdr was varnished on the outside... 

According to Marshall (Ref 2), there were also devices called German Spills, which resembled Daddow s squib, but no description of them is given... 

Petard de mineurs (Fr). See under Miner s Squib in this Vol, M134-R... 

A special category of ignition system is the cartridge actuated device (CAD) also known as the Propellant Actuated Device (PAD) which serves to generate the mechanical force to close switches (in the manner of a squib) or to perform otherwise mechanical work (Vol 2, C70-R Ref 138, p 167)... 

A pyrotechnic igniter consists of a basket of inorganic combustible materials, such as boron-potassium nitrate, which are usually in the form of pellets. This basket is also filled with a squib which provides a means of initiating the igniter. 

The IR detectors are usually connected to a controller that supplies power to the detectors and acts as a signal processor and output device. A typical controller monitors up to four detectors and energizes an output when any one of the detectors senses IR radiation that exceeds the alarm threshold level. The controller also contains the circuitry that checks the detectors and electrically supervises the interconnecting wiring to the explosive squibs or solenoid valves by trickling a small current through the external circuits. 

Reliable operation of the system is ensured by the ability of the Detonator Module to continuously monitor the input circuits and the detonator output circuits, to supervise the coil and wiring of the solenoid valve or squib, as well as to perform a self-test procedure to allow verification of other critical circuits. 

A typical high speed deluge system uses an electrically actuated (solenoid or squib) valve to initiate the flow of water from the nozzles. See Figure 9. The valve is positioned as close to the nozzles as possible. The piping between the valve and nozzles is fully primed and contains few if any air bubbles. 

CONTAINS SQUIB THAT MUST BE REPLACED AFTER EACH FIRING)... 

Figure 3. Typical Squib Actuated Rupture Disc Configuration...

Table I Is a brief overview of available fast action deluge. The Primac is a squib actuated deluge valve. The system...

The explosive rupture disc system Incorporates the same principle as Halon type explosive disc system, except that water is used as the extinguishing agent. In ultra high speed applications, there is a squib and rupture disc at each nozzle. 

On a Squib operated system, the igniter wire can be supervised but condition of explosive is not known. 

NOTE C After firing of the squib operated systems disc or caps... 

NOTE D Squibs have a shelf life and should be periodically replaced. 

Igniter Small device loaded with an explosive that will deflagrate the output is primarily heat (flash), sometimes referred to as a squib. 

If an explosive train is only required to ignite a main composition, an igniter that produces a flash instead of a detonation is used. Explosives of this kind are known as deflagrating explosives. Similar to detonators, igniters can be initiated by electrical means, friction, flash, or percussion. An example of an igniter is a squib, a small explosive device loaded with an explosive that deflagrates. Its output is primarily heat.8... 

Pyrolants deflagration detonation gas generators, igniters, fireworks, squibs, safety fuses detonators, primers, initiators, detonating fuses... 

SQUIB A small tubular hrework, containing gunpowder, that makes a hissing sound and then explodes. 

Electric Match (Squib) A metal wire is coated with a dab ... 

Igniters, which include devices called squibs, lighters and firing devices, etc are used for initiating expl or pyrotechnic compns whose nature is such that it is desirable to use flame or flash for their initiation and not a shock as produced by primers or detonators. 

The DuPont Co makes also electric igniting devices, called electric squibs (Ref 50, pp 94-5). Three types of US electric squibs patented by Burrows et al, are described in Ref 44, pp B212 to B214... 

---