Air flow studies for personnel explosives screening portals. [Explosives vapor diffusing through an individual's clothing is collected and identified]
An explosives vapor detection method is under development to search personnel for contraband explosives in a portal configuration. In this, the explosives vapor diffusing through an individual's clothing is collected and identified. This process consists of three phases: (1) the efficient collection of the explosives vapor from the subject's body with minimum dilution; (2) the ''preconcentration'' of explosives molecules into a smaller, more concentrated volume; and (3) analysis by a sensitive detector. An Ion Track Instruments preconcentrator and a Phemto-Chem 100 Ion Mobility Spectrometer detector were employed in these explosive vapor flow studies. Extremely high system sensitivity is required (approximately 1 part per 10/sup 14/) because of the very low vapor pressure of many explosives, the very short search times allotted for suitable throughput (6 to 15 seconds), and dilution during collection. Experimental portal configurations were semi-laminar downward flow, upward flow, complete mixing of air within the portal, and sideways flow in a modified XonTech portal. Standard explosive samples were 10 grams of DNT or 0.5 gram of TNT in a small plastic bag placed in various positions on a mannequin in the portal. The most effective air flow and collection method was a downward, semi-laminar flow over the body cross-sectional area combined with a vacuum flow collection funnel of about 12 inches diameter beneath the grating floor of the portal. The average improvement in detection of the downward flow over complete mixing in the portal was a factor of 5. The side flow portal is nearly equivalent in efficiency but is lower in some extreme mannequin sample positions by a factor of about 2. 4 figs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6528104
- Report Number(s):
- SAND-87-0822C; CONF-870743-1; ON: DE87007772
- Country of Publication:
- United States
- Language:
- English
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