Further development of technologies for searching for explosives and explosive objects in open areas, transport facilities and transport infrastructure.

Further development of technologies for searching explosives and explosive objects in open areas, transport facilities and transport infrastructure.

Further development of technologies for searching for explosives and explosive objects
in open areas, transport facilities and transport infrastructure

PETRENKO Evgeny Sergeevich
GORBACHEV Yuri Petrovich, Candidate of Technical Sciences
IONOV Vladimir Vladimirovich,
KOROLEV Nikolay Valentinovich

Source: Magazine «Special Equipment» No. 6 2007

Previous articles [1, 2] provide information on new developments in the field of explosives and explosive objects (EOD) search in open areas, transport facilities and transport infrastructure. The developments were aimed at increasing the reliability of EOD and EOD detection using portable (portable) EOD detectors of the Pilot-M type [3] in conditions of intense turbulent flows and/or low temperatures.

Further research and testing have made it possible to find a number of other original technical solutions and technologies that facilitate the successful solution of the problem of searching for explosives and explosive remnants in various conditions.

Examination of suspicious objects and baggage with a relatively isolated internal volume for the presence of explosives and explosive ordnance has always presented great difficulties, especially if opening this volume is associated with a real threat to the operator due to the danger of provoking an unauthorized activation of an explosive device. In many cases, the solution to the problem can be ensured by using flexible, rigid or semi-rigid endoscopes designed for visual inspection of hard-to-reach places and cavities, including light-insulated ones and those with small entry holes [4].

Flexible endoscopes are based on fiber optics and have two fiber optic bundles: for illumination and direct viewing of the examined space with the possibility of a circular view due to the controlled movable end section of the working part. Rigid endoscopes are metal tubes of different lengths and diameters with a built-in system of optical rigidly fixed elements and a fiber optic illumination bundle. Semi-rigid endoscopes have the features of flexible and rigid endoscopes.

Unfortunately, in real conditions, the possibilities of visual detection and identification of explosives and explosive ordnance, which have a large variety of types and designs, using endoscopes are significantly limited. In the case of equipping the working part of the endoscope with a tube to which an explosive vapor absorption unit and an air pump are attached, a real opportunity arises to conduct not only a visual inspection of the internal contents, but also a gas analysis in the immediate vicinity of the suspected explosive or explosive charge [5]. Fig. 1 shows a version of a flexible endoscope in such a design. The endoscope consists of a working part 1, an eyepiece 2 with a control unit and a lighting unit 3 with a battery. It is also possible to use video endoscopes. A tube 4 with a diameter of 4-8 mm is attached to the outside of the working part 1. When using a flexible endoscope, tube 4 must also be flexible. At the outlet end or in another place of the tube 4, an absorption unit of explosive vapors 5 is placed, made, for example, in the form of a mesh-concentrator from the kit of a portable explosive vapor detector, and an air pump 6. As such a pump, both special vacuum pumps can be used, for example, for inflating and deflating air mattresses, and simple vacuum cleaners such as car vacuum cleaners. In the event that substances or devices that may be related to explosives or explosive ordnance are detected inside an object or baggage examined with an endoscope, the end section of the working part 1 with the end section of the tube 4 is brought to this substance or device and the air pump 6 is turned on. The air flow with microparticles and explosive vapors passes through the tube 4 and hits the absorption unit of explosive vapors 5. The process of such air sampling for an object of examination such as an «attache case» takes from several seconds to several tens of seconds. After this, the explosive vapor absorption unit 5 is separated from the tube 4 and analyzed using various explosive detectors or chemical express tests for traces of explosives. In some cases, to increase the reliability of the result obtained during a single air sampling process, it is possible to repeat the cycle multiple times. If possible, with periodic switching of the air pump 6 to reverse flow.

Fig. 1. Diagram of device 1

Fig. 2. Diagram of device 2

Another promising technology for examining suspicious objects and baggage with a relatively isolated internal volume is associated with the use of a chamber made of elastic materials, the internal dimensions of which exceed the dimensions of the object being examined, with a device for its vacuumization. The chamber contains one or more openings with a joint unit having a removable unit for absorbing explosive vapors and a plug [6].

When the vacuum device 4 is switched on, the process of degassing the chamber 1 and the internal volume of the object being examined 2 begins with simultaneous intensification of vaporization in the explosive. The presence of multiple elements of the flexible tape 7, closely located to each other, contacting the surface of the object 2 at one point, ensures a significant reduction in the probability of complete simultaneous blockage of all zones of possible natural release of explosive vapors by the elastic material of the chamber 1. The air flow with microparticles and explosive vapors passes through the explosive vapor absorption unit 6. The vacuuming process for object 2 of the «attache case» type takes from several seconds to several tens of seconds. After which the explosive vapor absorption unit 6 is removed from the joint unit 3 and analyzed using various explosive detectors or chemical express tests for the presence of traces of explosives. In some cases, to increase the reliability of the result obtained during a single vacuuming process, it is possible to repeat the cycle multiple times with periodic switching of the vacuum device 4 to the flow reverse.Instead of the VV-6 vapor absorption units or together with them, units for absorption of narcotic (NS) and toxic substances (TS) can be used, which significantly expands the capabilities of the device for detecting hazardous substances.

Another direction of improving the equipment and technologies for examining various objects for the presence of explosives, explosive hazards, non-toxic substances and toxic substances is associated with the development of a new chamber vacuum technology, especially in cases where the objects of examination are motor vehicles, including heavy-duty trucks. In these cases, the difficulty of ensuring the chamber’s tightness for a long time under conditions of repeated sealing and vacuuming cycles comes to the fore, and especially when examining heavy-duty vehicles with contaminated chassis. In this situation, even powerful vacuum pumps with the corresponding power consumption may not cope with the influx of air from outside through contaminated chamber seals. The solution to this problem can be ensured by using one or more low-pressure sections of shock pipes [8], each of which is equipped with a diaphragm and a vacuum pump [9], as a vacuum device.

Figure 3 shows a diagram of such a device for detecting explosives and explosive hazards in suspicious objects, baggage and vehicles.

The device comprises a chamber 1, the internal dimensions of which exceed the dimensions of the object being examined 2 (suspicious objects, baggage or vehicle, including heavy-duty vehicles). Chamber 1 is made with a rigid, non-deformable body. One or more low-pressure sections 3 of shock tubes are placed in the upper part and/or on the side surfaces of chamber 1. The number of sections 3 is determined by their type (dimensions, speed and degree of achieved vacuuming) and the type of objects being examined 2. These sections 3 can be placed both inside chamber 1 and outside it. Each of the sections 3 has a destructible or movable diaphragm 4 with a diameter (or a characteristic size in the case of its non-circularity) from several centimeters to several tens of centimeters (depending on the types of sections 3 and the sizes of the objects 2 being examined), which ensures a fairly simple possibility of sealing the joints of the low-pressure sections 3 and their diaphragms 4, in contrast to the possibility of sealing the joints of the entry and exit gates (when inspecting transport) of chamber 1 in the analogue. The low-pressure sections 3 can be preliminarily evacuated using low-power vacuum pumps 5 during the extraction (exit) of the previous examined object 2 from chamber 1 and the placement (entry) of the next one.

Explosive vapor absorption units 6, for example in the form of a mesh concentrator from the portable explosive vapor detector kit, can be placed (for example, on rigid stands) both inside chamber 1 and inside each of the low-pressure sections 3 of the shock tubes. Instead of the VV 6 vapor absorption units or together with them, the NV and OV absorption units can be used.

When the diaphragms 4 are moved or destroyed, the process of intensive (up to supersonic) movement of air from chamber 1, which in this case acts as the high-pressure section of the shock tube, to the low-pressure section 3 begins with degassing of chamber 1 and the internal volume of the object being examined 2 with simultaneous intensification of vaporization in the explosive and separation of microparticles of the explosive from the surface of the object 2. Air flows with microparticles and vapors of the explosive pass through the absorption units of vapors of the explosive 6. The high speed of the process practically eliminates the negative impact on the results of the examination of a possible influx of air from outside through contaminated seals of chamber 1.

After the air reverberation in chamber 1 and low-pressure sections 3 has ceased, which takes several seconds, the explosive vapor absorption units 6 are analyzed using various explosive detectors or chemical express tests for traces of explosives. In the case of using drug and toxic substance absorption units, their analysis is performed using the appropriate detectors or chemical express tests. In some cases, to increase the reliability of the result obtained during a single vacuum cycle, it may be repeated multiple times.

Thus, the presented technical and technological solutions allow to significantly increase the reliability of detection of explosives, high explosives, non-explosive substances and toxic substances inside various objects, including objects and baggage with a relatively isolated internal volume and vehicles. Developments in this area are ongoing, and there is hope for obtaining new positive results.

Literature

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2. Gorbachev Yu.P., Korolev N.V., Petrenko E.S., Ionov V.V. New Possibilities of Searching for Explosives and Explosive Objects Using Portable Detectors in Open Areas, Transport Facilities, and Transport Infrastructure/Special Equipment, 2007, No. 4.
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