A wide variety of potentially dangerous substances occurs in gaseous form, e.g. as pollutants in the air we breathe at work, at home, on the streets. As gases expand easily into large volumes they may be harmful even in areas far from their origin. Aggressive gases lead to corrosion of equipment or indicate the outbreak of fires etc.
Typical sensing applications regarding safety include
- workplace exposure monitoring
- car engine combustion control
- surveillance of corrosive gases in industrial environments d
- false alarm free fire detectionc
- control of sources greenhouse gases
Selected examples of nanoplus lasers in safety related applications include:
Workplace exposure monitoring: CH2O
Formaldehyde has been used in consumer and industrial products since the beginning of the 19th century. Currently the annual formaldehyde production accounts for 21 million tons. About 50 % are processed as adhesives in pressed wood panels. In 2004 formaldehyde has been classified carcinogenic by the International Agency for Research on Cancer. Since then formaldehyde concentrations have been strictly controlled in the production process as well as in the finished product. Laser-based measurement systems are required to detect the maximum levels of 0.01 ppb (USA) and 2 ppb (EU). [9, 22, 78]
Leakage control in gas pipelines: CH4
Leaks of CH4 may cause dangerous situations and are hard to locate precisely. Hence, maintenance of underground pipelines produces high costs. CH4 leaks are also an important source for greenhouse gases. With TDLS a strong tool is available to manufacture portable leak detectors.
Early fire detection: CO
Early fire detection technologies rely on highly sensitive detection of carbon monoxide. Coal-fired power plants, steel mills or biomass deposits use these smoke detectors to increase process and workers safety.
Quality control in natural gas pipelines: CO2
CO2 is a natural diluent in oil and gas deposits. When it reacts with H2S and H2O steel pipelines corrode. Real-time monitoring of CO2 at natural gas custody transfer points is necessary to avoid contaminated gas from flowing downstream. Immediate measures may be taken to purify the natural gas.
Control of toxic substances: SO2
SO2 is a highly reactive and toxic gas which leads to severe respiratory disorders, hence its emissions have to be controlled.
Control of hazardous gases: H2S
H2S occurs as a corrosive, toxic and explosive side product in the petrochemical industry. Continuous monitoring of this hazardous compound is critical to avoid corrosion of natural gas pipelines and ensure workers safety. Real-time analysis is essential to guarantee that burning fuels are H2S clean in order to prevent acid rains. [3, 69, 76]
Surveillance of volcanic activities: CO2
Early warning systems for volcanic eruptions continuously monitor CO2 by TDLS, as it is an abundant volcanic gas.
Acetylene (C2H2) is used for gas welding, because the flame is easily adjustable. At the same time, acetylene is highly explosive when it mixes with oxygen or when there is a sudden change in pressure or temperature. Even at relatively low temperatures, like 306°, a little electric spark is sufficient to cause an explosion. For workers' safety the acetylene concentration has to be continuously monitored.