Destroyers of explosive devices and other explosive objects.
PETRENKO Evgeny Sergeevich
DESTROYERS OF EXPLOSIVE DEVICES AND OTHER EXPLOSIVE OBJECTS
The problem of searching for and defusing explosive devices and other explosive objects (ED), unfortunately, continues to be relevant throughout the world due to the increasing attempts to use these devices to carry out terrorist acts in peacetime and the need to solve an ever-increasing volume of tasks in the field of humanitarian demining.
The issues of searching for and identifying ED, using various equipment and devices to perform these works, localizing the possible consequences of an explosion and protecting personnel are discussed in previous issues of the Special Equipment magazine.
Destruction of ED at a distance of more than 10 m is carried out by shooting them from various types of small arms and is widely used both abroad and in Russia.
The specifics of destroying explosives in this way are the subject of a separate article.
This article deals with short-range explosives destroyers, which are limited to a distance of less than 10 m.
The sensitivity to impact of many explosives (HE) is quite high, which can lead to an explosion of explosives when attempting to destroy them using various types of destroyers.
The probability of triggering (exploding) a high explosive device increases significantly if it contains initiating explosives, a detonator cap or a fuse, especially if the latter is transferred from the transport position to the combat position.
In this regard, the optimal destroyers are those whose use, on the one hand, would ensure reliable destruction of the high explosive device as a structure, and on the other hand, would reduce the risk of explosion of such an object to a minimum, which is important when performing demining operations in urban and industrial areas in peacetime.
The effectiveness of the impact of various types of damaging elements, which include high-speed water jets, bullets, cumulative jets, fragments and other compact damaging elements, is determined by both the mass-kinetic parameters of these elements, their shape and material, and the parameters of the explosive reactive element.
The determining parameters of the explosive reactive element in terms of its vulnerability include:
- the type of explosive, its temperature and the presence of impurities;
- material, thickness and shape of the explosive device body;
- type of fuse and the presence of elements of non-removability and non-neutralization in its composition;
- presence of a camouflage layer of soil or shielding structures;
- orientation of the explosive device relative to the trajectory of the striking element.
In addition, under identical conditions of work, the result is also determined by probabilistic processes.
When impurities such as sand or crushed glass are added to powdered explosives, the sensitivity of the explosive to impact increases sharply; the addition of a paraffin-stearin mixture, on the contrary, reduces the sensitivity.
Liquid explosives with air bubbles are more sensitive to impact than explosives that do not contain bubbles.
For some explosives, sensitivity to mechanical loads strongly depends on the temperature of the explosive.
Thus, when dynamites freeze, their sensitivity to impact and friction increases so much that any work in industry using them is prohibited. TNT is characterized by stability of parameters of sensitivity to external influences, detonation velocity and heat of explosive transformation in a wide range of positive and negative temperatures.
For condensed explosives in a case, the quality of the surface of the case, which is in direct contact with the explosive, is of great importance in terms of the reaction to the initiating effect from the striking element.
Thus, in particular, the roughly processed metal inner surface of the explosive charge body, which is in direct contact with the explosive, significantly increases the probability of initiating the explosion of the main charge when exposed to a striking element, all other things being equal.
The sensitivity of the same explosive depends on the “history” of the charge, i.e. on the impacts previously experienced by this charge, arising from being shot through by a bullet, exposure to explosive and vibration loads.
In particular, the powder retarder in the UZRG-M type fuses for hand grenades, after being exposed to shock loads that occur during warehouse explosions, can turn into an instant-action detonator, causing the grenade to explode in the hands when attempting to use it as intended. High explosives in service, as a rule, do not explode when shot through once by an AKM assault rifle with BZ or BZT bullets.
However, an explosion or fire cannot be completely ruled out. Studies conducted on various incompletely loaded explosive devices and ammunition loaded with cast TNT and alloys based on TNT, hexogen and aluminum have shown that a single shot through them with 7.62-mm bullets (1943 model cartridge with a BZT bullet) from an AKM assault rifle and other striking elements with similar mass-kinetic parameters does not lead to an explosion.
Repeated shooting can lead to an explosion, and the probability of an explosion increases exponentially with the number of hits. In particular, when shooting ammunition from an AKM assault rifle, the probability of an explosion approaches 1 with 6 — 7 hits, even with a spread of hit points along the projection of the ammunition.
This is facilitated by the finely dispersed (dust-like) highly sensitive fraction of explosive particles formed during previous shootings, covering the outer and inner surfaces of the ammunition body.
Exposure to chemically active environments (acids, alkalis) leads to the decomposition of explosives with the formation of secondary products, which can be both safe and very sensitive to external influences.
TNT, which is very insensitive under normal conditions, after contact with an alkaline environment at elevated temperatures forms decomposition products that significantly increase the danger of handling it.
A significant danger is posed by picrates formed during the interaction of picric acid, which was widely used to equip ammunition until the end of World War II, with metals in the presence of atmospheric oxygen and moisture.
The presence of screens in the form of various types of housings can both reduce the effectiveness of the striking element on the explosive charge and increase it.
In particular, the presence of a strong casing can lead to the transition of combustion excited by the penetration into detonation of the entire volume of explosives, while in the presence of a weak casing, its destruction will occur with dispersion and ignition of a small part of the explosives without an explosion.
Research using compact striking elements and various types of explosive devices have shown that their explosion is possible at striking element speeds of more than 900 m/s and a mass of 1 g. With an increase in the values of the mass-kinetic parameters of striking elements, the probability of an explosion increases.
The presence of an anti-removal element in the fuse may cause it to trigger when attempting to destroy the explosive device. In standard engineering munitions, as a rule, the detonator device ensures a delay in the triggering of the detonator cap after receiving a signal from the target sensor or the anti-removal element within 200 — 300 ms.
At a certain intensity of the damaging effect, conditions are ensured when the time of destruction and the beginning of the scattering of parts of the explosive device body will be less than or equal to the triggering time of the fuse, taking into account the delay time.
In this case, either one detonator cap with an intermediate detonator will explode (if there is a strong fuse body), or an explosion will be impossible at all due to the destruction of the weak fuse body.
In particular, such conditions can be ensured at speeds of striking elements of the order of 1000 m/s and a mass of the order of several grams, as well as at high speeds, but when using low-density materials with a sufficiently strong phlegmatizing effect in these elements, such as water.
For the destruction of explosive ordnance at a distance of up to several meters, a whole series of special devices based on the use of various types of destructive effects have been developed in Russia and abroad.
Currently, for the destruction of explosive ordnance without a case or in wooden, plastic or cardboard cases, which is typical primarily for improvised explosive devices, gunpowder-actuated hydrodynamic devices — hydrodynamic destroyers — are widely used.
The devices operate on the principle of creating a powerful hydraulic jet with a speed of up to 220 … 300 m/s and capable of destroying explosive ordnance in relatively fragile cases.
These devices can be used both from a vehicle and from a special stand installed on the ground.
One of the versions of the device, developed in Great Britain for remote-controlled vehicles of the Hunter type and designated SA91, is a thick-walled aluminum tube, filled with water before use and having a powder cartridge with an electric igniter. The mass of the empty device is 400 g, with water — 540 g. The SA94 Pigstick device (designated L2A1 in NATO) is made in a similar way and differs from the first version in its dimensions.
The strength of its body allows multiple use with an empty device mass of 3.0 kg. The range of damaging effects does not exceed 10 — 15 cm.
Experimental studies conducted to assess the effectiveness of the impact of such charges on various explosive devices have shown their relatively low destructive capacity. A mine of the TM-62M type, without being destroyed, moves several centimeters.
If it is equipped with a detonator with a magnetic target sensor, an anti-removal element or a bottom (side) detonator of the MUV type, such an impact will lead to the detonation of the detonator and the explosion of the main charge of explosive.
In addition to hydrodynamic devices, a number of devices for non-detonation destruction of explosive ordnance have been developed abroad. Their operation is based on throwing a 200 g lead striker — the MPD destroyer (Great Britain), a 300 g high-strength steel striker — the EG-2 destroyer (Switzerland), and a cumulative jet — the ZL-100/01 and DNW HL60 charges (Austria). The devices listed above have a range of up to several meters and can be used to neutralize various explosive ordnance, including those in strong casings.
Due to the need to place hydrodynamic and a number of other types of explosive ordnance destroyers with ferromagnetic parts in the immediate vicinity of the object being destroyed, there is a possibility of triggering fuses with a magnetic target sensor when attempting to neutralize them in this way.
When a hydraulic jet or other destructive element hits the projection of a detonator cap or intermediate detonator with initiating or high-explosive explosives, their detonation and, accordingly, the explosion of the main explosive charge may be initiated. In addition, explosive devices with non-removable elements may be triggered.
In all cases, massive metal parts of the rack of the destroyer itself may be thrown by the explosion over distances of tens and even hundreds of meters, thus posing a serious danger to the surrounding area.
In Russia, as well as abroad, a whole series of short-range explosive ordnance destroyers have been developed and are being successfully used in practice.
Among the first to solve the problem of destroying explosive ordnance were the hydrodynamic destroyers of the “Vystrel” series (“Vystrel-M”, “Vystrel-2M”), photo 1.
Photo 1 Hydrodynamic destroyer
of the “Vystrel” series of explosive ordnance
Subsequently, the domestic industry developed a number of other types of explosive destroyers, the action of which is based on the use of the energy of cumulative jets, hypervelocity liquid jets and compact destructive elements.
A characteristic feature of most of these destroyers is the use of a small (up to 20 — 30 g) charge of explosives, which allows them to be used even in close proximity to the glazing of buildings and structures without causing damage.
Representative examples are the products Geyser (Typhoon), RVP-1, RVP-2, RVP-3, and Liniya. Destroyers based on sections of detonating extended charges (DEC) have proven themselves well during full-scale tests.
The range of the above destroyers is from zero to several tens of centimeters. At the same time, all destroyers, with the exception of the “Line”, are finally loaded ammunition, which necessitates the need to comply with the relevant requirements for their transportation and storage.
The “Geyser” (“Typhoon”) explosive detonator implements the idea of using thin cumulative jets, the diameter of which is smaller than the critical detonation diameter of most explosives, including hexogen, which is part of the detonator cap.
The critical detonation diameter is understood as the minimum diameter (layer thickness) of the explosive along which the detonation wave is capable of propagating without attenuation.
Unfortunately, in practice, detonator caps and explosive charges are in most cases shielded by the body of the explosive and detonating devices, packaging, etc., after passing through which the cumulative jet begins to disperse in a certain solid angle, which in turn significantly increases the probability of initiating an explosion of explosives, and first of all, explosives included in the blasting means.
The portable barrel system for the destruction of explosive ordnance without initiating the detonation of its main explosive charge has an original design and operating principle. The system is made in the form of a portable lightweight barrel guide on a tripod, providing for the firing of low-velocity so-called “spear-shaped” ammunition.
Such ammunition is made in the form of a metal perforated tube, equipped with a powder explosive charge, with a ballistic tip and a bottom fuse. The system ensures the penetration of the spear-shaped ammunition into the explosive, including anti-tank mines in strong cases, and its detonation inside this object.
Research using various explosive samples has shown that when the spear-shaped ammunition is triggered, the explosive, including the finally loaded ones, are destroyed as structures without detonation of the main explosive charge.
The remains of the case, equipment and fuse are scattered within a radius of up to 5 m.
This system can be effectively used both for the destruction of identified explosive ordnance and for the destruction of large-sized baggage with a suspicion of the presence of such objects without causing damage to surrounding objects, at a distance from several tens of centimeters to several meters.
The “Line” destroyer, designed for the destruction of explosive ordnance mainly without initiating the detonation of their main explosive charge from a distance of 0 — 50 cm, is usually manufactured independently at the site of the work using standard blasting equipment based on No. 8 detonator caps.
“Line” ensures destruction of explosive warheads with uncased explosive charges (based on TNT blocks, plastic and elastic explosives), explosive warheads with charges in plastic (MON-50, PMN type mines), wooden (PMD type mines) and thin-walled metal cases.
The design of the destroyer and the method underlying it are patented.
The core of the destroyer is a cassette made of energy-absorbing material (foam plastic from household appliance packaging, polyurethane foam) and containing holes for detonator caps.
For the destruction of explosive devices with a shell-less main charge of explosives based on standard TNT blocks weighing 75, 200 and 400 g, it is sufficient to use one detonator cap No. 8-A. For the destruction of explosive devices and mines in plastic cases (such as MON-50 mines) and thin-walled metal cases (such as SZ-1 charges), it is necessary to use at least 3 detonator caps simultaneously.
In most cases, the explosive is in opaque packaging (a plastic bag, a bag, an attaché case, etc.), when visual identification of the explosive is difficult or impossible.
In this case, when destroying it, they focus on the simultaneous use of several detonator caps.
In addition, to destroy large explosive or baggage suspected of containing explosive, it is necessary to simultaneously use several cassettes for simultaneousimpact across the entire projection of the destroyed object.
Such a scheme for using the destroyer, on the one hand, eliminates the effect of accumulation of damage, in which the probability of an explosion of the explosive element increases sharply, on the other hand, it ensures maximum efficiency of the destructive impact on the explosive element due to the interaction of individual destruction zones.
For ease of installation of single cassettes or cassette blocks, wire supports made of non-ferromagnetic materials (e.g. aluminum), nylon cord, and double-sided adhesive tape are used when using them.
It should be borne in mind that when simultaneously detonating several detonator caps inside a room, each with a charge weight of 1.3 — 1.5 g, in one or more cassettes, some part of the glazing may be damaged. The probability of damage to the glazing is especially high when using the destroyer in a limited-volume room with high air humidity.
To completely eliminate the possibility of damage to the glazing, foam compositions of construction spray cans such as “Macroflex” and Penoflex”, polyethylene or paper bags with sand, a fire hose with water, etc. are used, placed near the explosive device without displacing it.
A destroyer whose action is based on the use of liquid cumulation has shown high efficiency in destroying explosive devices from a distance of 0 … 50 cm, mainly without initiating the detonation of their main explosive charge.
Such a destroyer is also made independently at the site of the explosive ordnance disposal work.
To create a destroyer, a plastic bottle with a capacity of 0.33 … 2.25 l or a polyethylene bag, a charge of plastic explosive of the PVV-4 type (PVV-5A, PVV-7, PVV-12) or elastic explosive of the EVV-11 type weighing 5-35 g and a blasting agent of the EDP (EDP-r) or ZTP type (Fig. 1) are used.
The explosive charge is made in the form of a funnel, for example, by uniformly placing the explosive along the inner surface of the funnel-shaped upper part of a plastic bottle.
A detonator cap is installed in the neck of the funnel strictly along its axis, and the funnel is lowered to the bottom of a plastic bottle or plastic bag filled with water (in winter conditions, it is advisable to add glycerin to the water to prevent it from freezing).
The funnel is positioned in the body so that its base is directed towards the explosive charge.
To increase the destructive effect, it is advisable to bring the base of the funnel as close as possible to the wall of the housing, while preventing the formation of air bubbles in the internal cavity of the funnel.
Fig. 1. Liquid-based explosive device destroyer
a) version of the explosive device destroyer with a housing made of
a fragment of a plastic bottle
with an axial placement of the explosive charge;
b) a version of a VOP destroyer with a body made of
a fragment of a plastic bottle with the placement
of the explosive charge at a certain angle to the axis of the body;
c) a variant of the explosive destructor
with a body made of a polyethylene bag.
1 – an easily destructible body in the form of a fragment of a plastic bottle or a polyethylene bag;
2 – a water-based liquid;
3 – an explosive charge;
4 – the upper funnel-shaped part of a plastic bottle;
5 – a detonator cap of the blasting agent
When a charge of explosive explodes, a powerful liquid jet is formed, the speed of movement of the warheads of which can reach 4000 … 5000 m/s, which is sufficient to destroy most explosive devices as structures, including those in strong hulls.
At the same time, water has a significant phlegmatizing effect on the explosive charge of the explosive device being destroyed, ensuring its destruction mainly without initiating detonation.
The impact of the explosion of a propellant charge of explosives on the surrounding space is minimal due to the damping of the shock wave and detonation products by layers of liquid external to the funnel, filling the easily destructible body.
The high speed of the striking element allows us to expect a favorable outcome in the destruction without triggering explosive devices with non-removable elements.
There is a similar destroyer of industrial production, which has a slightly greater power of action compared to the one considered.
To destroy explosive reactive explosives at a range of up to 5…6 m, a destroyer is used based on, for example, a TNT drill block weighing 75 g and a plate 1…3 mm thick made of plastic metal (copper, case steel, some types of brass) with a diameter of 10…30 mm.
The metal plate is first given the shape of a segmental funnel, similar to the funnels of projectile-forming charges (colloquially — charges of the “impact core” type), which is subsequently placed without an air gap on the end of the drill block opposite the socket for the detonator cap.
When using in practice all types of short-range explosive ordnance destroyers without exception, it seems advisable to observe a number of rules that help improve the safety of the work.
In particular, we can talk about the following:
- when approaching a VOP, the identification of which is difficult or impossible, assume that in the most complex case it contains a magnetic target sensor, an anti-removal element, an incapacitating element, a target tension sensor, a timer (clock) mechanism and a remote control channel (radio fuse or wire line);
- block the remote control channel (radio fuse — using a Perseus type radio fuse blocker; wire line — by cutting it off at a safe distance from the VOP);
- neutralize the possible presence of a target tension sensor by known methods;
- taking into account the practice of setting the response time of fuses with a timer (clock) mechanism, a multiple of 1 hour, 30 minutes, 15 minutes, it is advisable to install the destroyer at the safest moments of time, for example, at 11:37 am, 9:53 am, etc.;
- when installing the destroyer near a VOP, it is necessary to exclude the use of ferromagnetic materials in the composition of the weapon, personal protective equipment (sapper suit), improvised means and tools;
- do not allow tilting or plane-parallel displacement of the VOP.
Naturally, all actions on the production and, especially, the use of both homemade and industrially produced explosive device destroyers must first be carried out under the guidance of experienced specialists at specialized training bases using mock-ups and not fully equipped (without detonators) explosive device of various types.
Only after this is it possible to use such destroyers in practice.
The specifics of Russian conditions (the relative high cost of industrially produced explosive ordnance destroyers, the need for constant training of personnel using such destroyers, and the high intensity of calls to explosive experts in connection with the increasing number of cases of detection of various suspicious objects) determine the predominant use in the country of the above-mentioned homemade designs of short-range destroyers.
Thus, due to the diversity of destroyers, it is advisable to focus on the use of such models that, on the one hand, would ensure reliable destruction of various types of explosive ordnance (from improvised caseless mines to anti-tank anti-bottom mines of remote installation in especially strong cases) without initiating the detonation of their main explosive charge, and on the other hand, would allow the destruction process to be carried out from distances from zero to several meters.
It should be borne in mind that for the operator, regardless of the degree of his equipment with personal protective equipment, explosive devices equipped with fuses with a tension (scattering), seismic or optical target sensor, as well as fuses with remote control or with a self-destruction mechanism (timer mechanism) pose a greater danger.
Under these conditions, it is obvious that the use of short-range destroyers will be justified when the use of small arms is impossible for one reason or another.