Development of Aerosol Monitoring Instrument and Results from Monitoring Emissions of Contained Detonations

Abstract

To determine the airborne emissions that occur when conventional munitions are destroyed by open burn/open detonation (OB/OD), munitions shots were carried out in a large underground (4650 m³) chamber. Carrying out the tests in a chamber allows the total emissions to be measured, which is not possible in open-air testing. We report here the development of an instrument to measure the time-dependent mass concentration and aerosol size distribution of respirable aerosols (< 10 μ m) from detonations of artillery projectiles in the underground chamber. The instrument incorporates an on-line diluter and real-time cascade impactor for aerosol monitoring. Design, flow modeling, construction details, and results from the instrument are given.

Particulate emissions from detonations of twenty four 155 mm artillery projectiles, with a total of 377 lbs net explosive weight, were monitored. Aerosol measurements from the two duplicate tests were very similar. Aerosol mass concentrations showed rapid decreases from 37,000 and 65,000 μ g/m³ for the first samples for the two tests, 14 and 17 min after detonation, to near 20,000 μg/m³ at 20 min after each detonation. Thereafter the concentration decreased less rapidly to several thousand μg/m³ at 90 min after the detonation. Aerosol mass concentrations peaked in the 0.3–0.6 μm diameter range during the first 30–60 min of sampling and shifted to smaller particles (< 0.3 μm) toward the end of the sampling period (90 min) as turbulence decreased in the detonation chamber and large particles settled out.

The data were highly reproducible between the two tests, indicating that the instrument performed satisfactorily. The data will be used to help determine the characteristics of dust emitted from OB/OD shots for munitions demilitarization and will provide a baseline for designing future studies to monitor the airborne emissions from full-scale open-air munitions demilitarization tests.

Acknowledgments

The author would like to thank the sponsor of the work, the Defense Ammunition Center in McAlester, OK, Mr. J. Wheeler, Director, for their support and guidance during the program.