Detect-to-warn

Thus there are two separate and distinct missions of any system designed to detect both chemical and biological weapons, namely Detect to Warn and Detect to Treat. The presence of a chemical agent must be detected immediately in order to warn troops to put on protective gear. Biological agents must be detected and identified promptly in order to minimize the number of exposed troops however, immediate death or incapacitation is not likely. Instead, early detection allows early treatment and lower mortality rates. 

LP-4 is a high-level active protection that can detect to treat, detect to mitigate, or detect to warn and protect. LP-4 includes rapid, automated systems. LP-4 eliminates the human decision factor, but the complex and sophisticated automated systems require routine maintenance to ensure their proper... 

Detection. Many people can detect hydrogen cyanide by odor or taste sensation at the 1 ppm concentration in air, most at 5 ppm, but HCN does not have an offensive odor and a few people cannot smell it even at toxic levels. Anyone planning to work with hydrogen cyanide should be checked with a sniff test employing a known safe concentration. This test should be given periodically. Several chemical detection and warning methods can be employed. The most rehable are modem, electronic monitors based on electrolytes that react with hydrogen cyanide. 

Install flammable/toxic detection systems in buildings with alarms to warn building occupants of hazardous accumulations... 

Air intakes to heating and ventilation systems, air compressors for process, instrument and breathing air, and to prime movers for gas compressors, power generation and pumps should be located as far as practical from contamination by dust, toxic and flammable materials release sources. They should not be located in electrically classified areas. If close to possible vapor releases (as confirmed by dispersion analyses( they should be fitted with toxic or combustible gas detection devices to warn of possible air intakes hazards and snutdown and isolate the incoming air ductwork and fans. 

Various simple and sophisticated fire and gas detection systems are available to provide early detection and warnings of a hydrocarbon release which supplement process instrumentation and alarms. The overall objective of fire and gas detection systems are to warn of possible impending events that may be threatening to life, property of continued business operations, that are external to the process operation. 

Process controls and instrumentation only provide feedback for conditions within the process system. They do not report or control conditions outside the assumed process integrity limits. Fire and gas detection systems supplement process information systems with instrumentation that is located external to the process to warn of conditions that could be considered harmful if found outside the normal process environment. Fire and gas detection systems may be used to confirm the readings of major process releases or to report conditions that process instrumentation may not adequately report or be unable to report (i.e., minor process releases). 

Gas detection is provided in the petroleum industry to warn of and possibly prevent the formation of a combustible gas or vapor mixture that could cause an explosive overpressure blast of damaging proportions. There are two types of gas detectors used in the oil and gas industry. The most common and widely used is the catalytic detector. More recently, infared (IR) beam detectors have been employed for special "line of sight" applications, such as perimeter, boundary or offsite monitoring, pump alleys, etc. 

Probably the oldest need for trace detection was for the detection of poisons. Food tasters fulfilled that role, as did canaries when used by miners to warn of poisonous atmospheres underground. In more recent times, society has required the detection of other chemicals. Often a trained dog meets that need. Canine olfaction wiU be discussed in Chapter 3. 

Instruments designed to detect and warn about leaks, acetone escapes and small fires before they become serious, and maybe even trigger automatic fire-fighting equipment, can also be installed. 

Therefore, if a leak-detection system has been installed to warn of releases of toxic or flammable materials from a plant, the implementation of a process safety management system should include the detection system as part of the process (CCPS 1989 CCPS 1988). In this manner the leak-detection system will be subject to the facility s management-of-change procedures, and changes to the leak-detection system, will be carefully evaluated before being implemented. 

Early CWA detectors were quite primitive and included primarily chemical-reactive dyes in paints. These were insensitive and therefore unreliable (Smart, 1997). Later technology used more sensitive chemical dyes in other formats such as paper tickets. Modem detectors now consist of fieldable IR spectrometers and an alarm system designed to warn of the presence of CWAs on the battlefield or in an enclosed space. Several rehable tests for the diagnosis of CWA exposure have been developed. To detect HD exposure, the level of thiodiglycol, a metabolite of HD, is quantitated in the urine using a gas chromatography/mass spectrometry (GC/MS) analytical method (Jakubowski et al., 1990 TB MED 296, 1996). Nerve agent exposure is detected in the field by the use of a fieldable Ellman assay to determine chohnesterase inhibition in the blood (Ellman et al., 1961 TB MED 296, 1996). 

Level of protection 3 (LP-3) is a low-level active protection designed to detect and identify threat agents in time to execute therapeutic responses, but not quickly enough to warn occupants of the threat before exposure occurs. LP-3 requires a broad-spectrum detection and identification system that determines a threat agent within a time period necessary for operational response and treatment. 

The Board urge OCDM to give the highest priority to research and development work on detection, early warning, and rapid identification of biological and chemical warfare agents (June 6,1959). 

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