Application Note CBRNE 1825474 Stand-Off Detection of Toxic Industrial Chemicals in Industrial Complexes Using RAPIDplus Abstract The Remote Air Pollution Infrared Detector (RAPID) is a stand-off detector for the detection and identification of chemical agent clouds. The RAPIDplus mounted onto a stationary tripod was able to detect ammonia in industrial complexes up to a distance of several kilometers. The dimension and movement of the cloud could be estimated using a novel Video Overlay Mode (VOM). Additionally, the detection of a chemical agent in an industrial complex could be successfully demonstrated from a moving vehicle using the RAPIDplus installed on an optional shock-absorbing mount. Introduction In the current industrial age, hazardous substances are produced, stored and shipped in large quantities. An accidental or deliberate release of such substances can result in a chemical cloud that endangers civil population and first responder. By means of classical analytical methods (e.g. Ion-Mobility Spectrometry, Gas Chromatography Mass Spectrometry, test papers) chemical clouds are only measureable if a detector operator enters that cloud. Using these standard techniques, the dimension and movement of such a cloud are not assessable. Authors Lutz-Peter Müller, Holger Skupin, Thomas Elßner Bruker Daltonik GmbH, Leipzig, Germany Keywords Stand-off Detection Instrumentation and Software RAPIDplus FT-IR Spectroscopy RAPIDplus Control 2.0 Video Overlay Professional RAPIDplus Monitoring Industrial Complexes Detection on the move
Fourier-transform infrared spectroscopy (FT-IR) enables the passive detection and identification of pollutant chemical clouds from distances [1]. The passive detection of chemical agents is based on a spectral analysis of the ambient infrared (IR) radiation. Chemical agents (CA) disseminated in the atmosphere generate unique signatures (fingerprints) in the infrared spectrum that can be analysed by detection systems. Specifically, parts of the mid infrared range (700 cm -1 1300 cm -1 ) are of interest for this process, because in this spectral range the transparency of the atmosphere and ambient radiation provides an open window for the detection device [1, 2]. Here we describe the usage of a FT-IR based detection system for the long-range detection of ammonia released by an industrial site in Germany. Experimental Detection of pollutant clouds was carried out using RAPIDplus. The RAPIDplus consists of a scanner head assembly with the IR scanner window and a video camera, internal optics and a patented Rock Solid interferometer (Figure 1). The IR scanner is protected by an IR transparent ZnSe window. An internal temperature controlled black body is used as a defined radiation source to calibrate the instrument. The technical specifications of the sensor and scanner module are summarised in Table 1. Table 1: Technical specifications of the sensor and scanner module Technical specifications Spectral Range 700-1300 cm -1 Spectral Resolution 4 cm -1 Sensitivity Measurement Speed < 0.05 K for a single spectrum with a resolution of 4 cm -1 20 spectra/s at 4 cm -1 spectral resolution Azimuth Rotation max. 120 /s (360 ) Field of Regard (FOR) Field of View -10 to 50 elevation 16 mrad A standard Bruker reference library containing about 100 entries (including CWA, CWA simulants and important Toxic Industrial Chemicals (TIC) was used for data comparison and for identification. RAPIDplus configuration Scanner for spatial resolution Video camera ZnSe window Michelson interferometer Shock-frame for mobile operations on vehicles Figure 1: Schematic drawing of RAPIDplus.
For operation the remote sensor was mounted on a tripod or fixed to a shock mount installed on the vehicle and linked via an Ethernet cable to a field portable laptop PC. Instrument control was realised by the RAPIDplus Control 2.0 software equipped with a VOM. Measured interferograms were automatically transformed to IR spectra and matched to the spectra of target and interfering substances stored in the reference library. Based on an internally calculated correlation coefficient an alarm was triggered if a threshold value was exceeded (Figure 2). Brightness temperature diagram of ammonia Correlated IR spectrum of ammonia Relative brightness temperature (K) Wavenumber (cm -1 ) Figure 3: Brightness temperature diagram of ammonia, measured with different background temperatures. Ammonia always has the same concentration (c = 71 mg/m²) and temperature (36.4 C) and the background temperature varies between 27 and 44 C. In general, any chemical gas or vapour that has significant IR bands between 700 cm -1 and 1300 cm -1, is detectable by the RAPIDplus. A selection of the substance classes including typical examples is summarised in Table 2. In general the detection limits are in the low ppm range. For ammonia the detection limit is 1 ppm for a cloud length of 100 m and a temperature difference between cloud and background of 3 C. Figure 2: Analysed IR Spectrum of ammonia (blue line) compared with the library spectrum (green line). Table 2: Substance classes and exemplary agents included in the reference library Substance classes and exemplary agents Results Detectable TIC The RAPIDplus enables the detection and identification of airborne CA by real-time remote sensing. The detectability depends on the temperature difference between cloud and background, the cloud length and the concentration of the CA [1]. If the background temperature is higher (buildings or mountains) than the temperature of the cloud the IR radiation is absorbed, if the background temperature is lower (blue sky), an emission spectrum is observed (Figure 3). Characteristic IR signatures increase with an increasing temperature difference. If there is no temperature difference between cloud and background, no infrared signature is produced [3], however, in practice, this is rarely realised. For the typical environment, temperature differences between cloud and background are 1 to 5 C [4]. Aromatic compounds e.g. Benzene, Xylene... Inorganic TIC e.g. Ammonia, SO 2... Aldehydes and Ketones e.g. Acetone, Butanal... Organic acids e.g. Acetic acid, Formic acid... Ethers Halogenated hydrocarbons e.g. Diethyl ether, Dimethyl ether... e.g. Chloroform, Dichloromethane... Alcohols e.g. Methanol, Ethanol... Phosphorous organic compounds e.g. Triethyl phosphate, Trimethyl phosphate... CWA e.g. Sarin, Soman......
Detection of industrial emissions from long distances and cloud visualisation For long-distance detection the RAPIDplus, was set up outside an area of an industrial facility, more than 5 km away from the possible source of emission and the facility was monitored (Figure 4 and 5). Releases of ammonia were detected based on internally calculated correlation values by matching the acquired spectra with the library spectra of the target and of interfering substances (Figure 2). While scanning the area, an alarm for ammonia was triggered immediately. The position and dimension of the cloud was visualised by an overlay of the correlation data onto the picture of the scenery (Figure 6). RAPIDplus in front of the target Figure 4: RAPIDplus mounted on a tripod more than 5 km outside an industrial facility with a zoomed view of the target. Map of the detection site Industrial facility Position of RAPIDplus 1 km RAPID OpenStreetMap contributors, Licence: www.opendatacommons.org/licenses/odbl Figure 5: Map of the detection site to demonstrate the distance of RAPIDplus to the facility.
Visualised ammonia cloud using Video Overlay Mode Figure 6: Video Overlay Mode of an ammonia alarm with the correlation plot of the cloud. The shape of the visualised cloud allows the possible source of release to be determined. Even if the cloud is high above the ground or in inaccessible areas, detection and identification of the CA and monitoring of the movement is possible. The detection scenario described is comparable to an accidental release of an unknown or known agent, where a first responder unit comes to an area already contaminated. Measurement and identification of the agent released can be facilitated in minutes. Furthermore the source and the spread of the cloud can be estimated and a decision about the area to be evacuated can be made quickly. No background evaluation is necessary in advance. Mobile detection Detection on the move Mounting the RAPIDplus on a shock frame on top of a vehicle (Figure 7) allows not only the system to be used whilst the vehicle is stationary, but also facilitates detection whilst the vehicle is moving. For detection when the vehicle was underway, the software was used in the standard mode (Figure 8). Figure 7: RAPIDplus mounted on a vehicle for mobile detection.
Bruker Daltonics is continually improving its products and reserves the right to change specifications without notice. Bruker Daltonics 12-2013, CBRNE, 1825474 Standard Mode of RAPIDplus TM Software Elevation bar Azimuth circle Figure 8: Standard Mode on the move with an alarm for ammonia. The vehicle heading is in 0 direction. Direction and elevation of the sector scanned are represented by two simplified symbols (elevation bar and azimuth circle). For example this configuration enables scanning of an area in front of the vehicle while driving, so that driving directly into the hazardous zone can be avoided. As shown in Figure 8 an ammonia alarm was triggered during scanning the industrial facility from the moving vehicle. Conclusion The RAPIDplus allows the stand-off detection and identification of toxic industrial chemicals released into the air even from long distances (several kilometers). In the event of an accident or incident, due to its capability to visualise the dimension and movement of the chemical cloud, the possible source of the release can be approximated easily and quickly. Fast detection and identification, of chemical clouds from a distance are of utmost importance to initiate appropriate countermeasures in time, and minimise health risk for first responders and the civil population. References [1] Beil, A., Daum, R., Matz, G., Harig, R.: Remote sensing of atmospheric pollution by passive FTIR spectrometry in Spectroscopic Atmospheric Environmental Monitoring Techniques (Schäfer, K., Ed.) Proceedings of SPIE Vol. 3493 (1998), pp 32-43 [2] Griffith, P. R., de Haseth J. A.: Fourier Transform Infrared Spectroscopy, John Wiley & sons, New York / USA, 1986 [3] Beil, A., Baum, R., Johnson, T. J.: Detection of chemical agents in the atmosphere by passive IR remote sensing in Internal Standardization and Calibration Architectures for Chemical Sensors (Shaffer,R.E., Potyrailo, R.A., Eds.) Proceedings of SPIE Vol. 3856 (1999), pp 44-56 [4] Klenk, U., Schmidt, E., Beil, A.: Scanning Infrared Remote Sensing System for Detection, Identification and Visualization of Airborne Pollutants in Atmospheric and Biological Environmental Monitoring (Kim, Y.J., Platt, U., Gu, M.B., Iwahashi, H., Eds.) Springer 2009, pp 51-62 Bruker Detection Division of Bruker Daltonik GmbH Leipzig Germany Phone +49 (341) 2431-30 Fax +49 (341) 2431-404 sales@bdal.de www.bruker.com Bruker Detection Division of Bruker Daltonics Ltd. Coventry United Kingdom Phone +44 (2476) 855-200 Fax +44 (2476) 465-317 sales@daltonics.bruker.co.uk Bruker Detection Corp. Billerica, MA USA Phone +1 (978) 663-3660 Fax +1 (978) 667-5993 ms-sales@bdal.com