TRACE VAPOR GENERATOR FOR TESTING EXPLOSIVES VAPOR DETECTORS - LAW ENFORCEMENT STANDARDS PROGRAM

• NCJ Number: 36142
• Author(s): P A PELLA; R M MILLS
• Date Published: 1976
• Length: 40 pages
• Sponsoring Agency: US Dept of Justice; US Dept of Justice NIJ Pub
• Corporate Author: US Dept of Commerce
• Sale Source: Superintendent of Documents, GPO; National Institute of Justice/
• Publication Type: Statistics
• Language: English
• Country: United States of America

Annotation

VAPORS FROM EXPLOSIVES SUCH AS TRINITROTOLUENE (TNT) AND ETHYLENE GLYCOL DINITRATE (EGDN), AT KNOWN CONCENTRATIONS BELOW ONE PART PER BILLION, ARE REQUIRED TO DETERMINE THE DETECTION LIMITS OF COMMERCIAL VAPOR DETECTORS.

Abstract

A VAPOR GENERATOR FOR LAW ENFORCEMENT APPLICATION WAS DEVELOPED TO PRODUCE KNOWN TRACE CONCENTRATIONS OF VAPORS OF THESE EXPLOSIVES AND DINITROTOLUENE (DNT). KNOWN EQUILIBRIUM VAPOR CONCENTRATIONS OF THESE EXPLOSIVES ARE GENERATED AT SEVERAL TEMPERATURES BY PASSING DRY NITROGEN THROUGH A TEMPERATURE-CONTROLLED COLUMN PACKED WITH THE EXPLOSIVE DISPERSED ON AN INERT SUPPORT. THE EQUILIBRIUM VAPOR ENTERS A DYNAMIC GAS-BLENDING SYSTEM IN WHICH THE VAPOR IS PRECISELY DILUTED WITH AIR TO PROVIDE OUTPUT EXPLOSIVES VAPOR CONCENTRATIONS BELOW 1 PPB. THIS LAW ENFORCEMENT STANDARDS LABORATORY (LESL) REPORT DESCRIBES THE DESIGN OF THE GENERATOR, AND THE MEASUREMENTS MADE TO VERIFY THAT THE OUTPUT VAPOR CONCENTRATIONS ARE CLOSE TO THE EXPECTED VALUES. THREE EXPLOSIVES VAPOR DETECTORS OF DIFFERENT DESIGNS WERE USED TO DEMONSTRATE THE APPLICABILITY OF THIS SYSTEM FOR TESTING THE PERFORMANCE OF DETECTORS. VAPOR PRESSURES AND HEATS OF SUBLIMATION WERE CALCULATED FROM THE EQUILIBRIUM VAPOR CONCENTRATIONS MEASURED IN THIS WORK AND WERE COMPARED TO THE DATA REPORTED BY OTHER WORKERS. APPENDED ARE DATA ON THE COLUMN DESIGN AND THE HEATS OF SUBLIMATION AND VAPORIZATION, AS WELL AS A LIST OF REFERENCES. TABULAR DATA ON TEST RESULTS IS ALSO INCLUDED. (AUTHOR ABSTRACT MODIFIED) (SNI ABSTRACT)