Monitoring at Chemical Agent Disposal Facilities (2005) / Chapter Skim
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3 Properties of Measurements and Measurement Systems for Airborne Agents
3 Properties of Measurements and Measurement Systems for Airborne Agents
Pages 12-20
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From page 12... ...
. Methods of Detection Current monitoring systems used at stockpile disposal Mass Spectrometry facilities to detect the presence of chemical agent in the Mass spectrometric techniques involve ionizing the ambient air and measure its concentration use an approach analyte by either soft ionization, in which the analyte that involves air sampling.
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From page 13... ...
This approach is called historical monitoring. consideration leads to the result that the LOD depends on the The only way that the concentration of chemical agents width of the signal relative to the frequency of the noise, can be monitored in real time (i.e., less that 10 seconds)
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From page 14... ...
14 MONITORING AT CHEMICAL AGENT DISPOSAL FACILITIES A B FIGURE 3-1 Random noise distribution using Gaussian peak.
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From page 15... ...
For the detection of chemical agents, false negatives mean that agent was present at a concentration INTRODUCTION TO SAMPLING FOR GB, VX, greater than the alarm level, which is a potentially hazardous AND HD IN AIR situation, whereas false positives may mean that the demili An understanding of the key factors that impact monitortarization process has to be shut down unnecessarily. ing for GB, VX, and HD at stockpile sites is a prerequisite to Obviously, both situations are undesirable.
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From page 16... ...
One other complicating factor is that the environments of 75 to 125 percent. Also, at a true concentration of that must be sampled at stockpile disposal sites often contain 1.00 AEL, the 95 percent confidence limits for the reported dust and/or high humidity, and the temperature of the air concentration must be within ±25 percent of the actual being sampled may range from well below 0°F to approxi- concentration.
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From page 17... ...
recognizable detection indication, including today's computing technology enables this to be readily an alarm when necessary, as well as to provide an electronic accomplished by accommodating both a large number of record of measurement results. measurements and enabling more computationally demanding, For example, in the metering of the temperature of a higher-performance algorithms to be applied in real time.
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From page 18... ...
This implies highly reliable instruments, of chemical agent, somewhat in excess of the true concentra- which appears to be the case, and highly reliable tions, but still well below the alarm threshold. operators, which means constant training and A certain level of reliability from an automated detection, reinforcement of correct operating procedures.
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From page 19... ...
They have developed skills in operating and In chemical demilitarization activities, many decisions maintaining the equipment, so new designs must not contrahave a high cost associated with them. Failing to put the dict these learned skills but rather complement them in the system into a safe state when a signal occurs (a true positive)
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From page 20... ...
2002. Evaluation of Chemical Events at Army Chemical Agent Disposal Facilities.
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