RU82331U1 - HAZARDOUS DETECTOR - Google Patents

Abstract

A hazardous substance detector comprising an air sampling unit, an air sampling analysis unit and an analysis result display unit, characterized in that between the air sampling unit and the analysis unit in the air transport channel there is a device for reducing the turbulence of the flow in the form of a wire mesh diameter 0.01-0.04 of the inner diameter of the channel with a mesh size of 2-4 wire diameters.

Description

The invention relates to the field of gas analysis and is intended for the detection of explosives (BB) in leaky volumes. The invention can also be used to detect narcotic, toxic and toxic substances.

Numerous explosive detectors based on ion mobility spectroscopy (SIT) are known, containing an enlarged air sampling unit, an analysis unit for a sampled air sample, and an analysis results display unit [1, 2, 3].

The disadvantage of these detectors is the low sensitivity and high probability of false alarms.

Known detectors of explosives and other hazardous substances based on spectroscopy of the increment of ionic mobility (SPIP), containing an enlarged unit for air sampling, an analysis unit for a selected air sample and a unit for indicating the analysis results [4, 5].

The disadvantage of these detectors is the rather high probability of false positives due to the strong turbulence of the air flow coming from the air sampling unit to the analysis unit. Especially if various types of systems are used for sampling for remote sampling of air samples from the surface and from unsealed objects based on intensive air blowing of the object under examination, for example [6], and / or high turbulence of ambient air at the place of work.

The objective of the invention is to significantly reduce the likelihood of false positives without compromising sensitivity.

The problem is solved in that in a hazardous substance detector containing an air sampling unit, an air sample analysis unit and an analysis result indication unit, a device is arranged between the air sampling unit and the analysis unit in the air flow conveying channel in the form of a grid from a wire with a diameter of 0.01 ... 0.04 of the inner diameter of the channel with a mesh size of 2 ... 4 wire diameters.

The analysis of the claimed solution showed that a significant reduction in the probability of false positives is provided by placing a device between the air sampling unit and the analysis unit in the air flow channel to reduce the turbulence of the stream in the form of a wire mesh with a diameter of 0.01 ... 0.04 of the inner diameter of the channel with size cells to a clearance of 2 ... 4 wire diameters. Such a grid splits a single turbulent air flow into many separate small turbulent flows of relatively low intensity, which merge into one laminar flow. And this laminar flow already enters the input of the analysis block of the selected air sample, due to which the probability of false positives due to the initial turbulence of the flow with the taken air sample is significantly reduced. In this case, the sensitivity of the detector does not change.

Figure 1 shows a diagram of a detector of hazardous substances, figure 2 - a device for reducing turbulence of the flow in the form of a grid (enlarged compared to the image in figure 1).

The detector contains an air sampling unit 1, an analysis unit for the taken air sample 2, and an analysis results indication unit 3. Between the air sampling unit 1 and the analysis unit 2, there is an air flow transport channel 4. The diameter of the channel 4 is usually 8 ... 15 mm, length - from several millimeters to several centimeters, and structurally

channel 4 can be combined with one of blocks 1 or 2. A device for reducing the turbulence of flow 5 is usually placed in the inlet section of channel 4. The diameter of the wire of device 5 is 0.2 ... 0.4 mm with a mesh size of 0.7. .1.1 mm. Such grid parameters provide, on the one hand, the efficient conversion of turbulent flow into laminar flow on a sufficiently short section of the air flow transport channel 4, on the other hand, the minimum resistance to the flow movement.

The operation of the proposed hazardous substance detector does not differ from the operation of similar detectors. But due to the lack of turbulence in the sampled air sample coming into the analysis unit 2, the probability of false alarms is significantly reduced, regardless of the degree of ambient air turbulence at the place of work and the principle of operation of the air sampling unit 1.

Thus, the proposed technical solution provides an increase in the detection efficiency of hazardous substances by significantly reducing the likelihood of false alarms without reducing the sensitivity of the detectors.

List of sources of information:

1. T.L. Buxton, P.B. Harrington. Rapid multivariate curve resolution applied to identification of explosives by ion mobility spectrometry. - Analytica Chimica Acta 434, 2001, p. 269-282.

2. Flyer for the Vapor Tracer detector of Ion Track Instruments (USA).

3. Brochure for SABER 2000 detector of Barringer company (Canada).

4. Journal of Analytical Chemistry, Volume 56, No. 4, 2001, pp. 381-385.

5. US patent No. 5420424, MKI: H01J 49/40, 1994.

6. RF patent No. 2279051, IPC G01N 1/22, 2004.

Claims (1)

A hazardous substance detector comprising an air sampling unit, an air sampling analysis unit and an analysis result display unit, characterized in that between the air sampling unit and the analysis unit in the air flow conveying channel there is a device for reducing turbulence of the flow in the form of a wire mesh diameter 0.01-0.04 of the inner diameter of the channel with a mesh size of 2-4 wire diameters.