Signal conditioning, carbon dioxide

Maintenance "indicators" are available to help facility staff determine when routine maintenance is required. For example, air filters are often neglected (sometimes due to reasons such as difficult access) and fail to receive maintenance at proper intervals. Installation of an inexpensive manometer, an instrument used to monitor the pressure loss across a filter bank, can give an immediate indication of filter condition without having to open the unit to visually observe the actual filter. Computerized systems are available that can prompt staff to carry out maintenance activities at the proper intervals. Some of these programs can be connected to building equipment so that a signal is transmitted to staff if a piece of equipment malfunctions. Individual areas can be monitored for temperature, air movement, humidity, and carbon dioxide, and new sensors are constantly entering the market. 

Fixed installations, such as water spray systems, halon systems, sprinkler systems, carbon dioxide extinguishing systems, explosion suppression systems, and other fire protection installations are often provided with flow and trouble detection switches connected to transmitters. A signal indicating the condition of the system should be sent to the attended location(s). 

The use of conductance as a measure of the solution composition is limited unless some other control of the composition is possible. Figure 6 illustrates a schematic of the apparatus used to follow the crystal growth of calcite from calcium bicarbonate solutions under constant composition conditions. In this case, the carbon dioxide concentration is kept constant by the flow of a water-saturated mixture of carbon dioxide and nitrogen gas. The conductance is monitored using an a.c. bridge with the analog signal... 

Cosgrove et al. in 1985 (828a) showed that it was possible to detect hydroxyl radicals in an aqueous extract of the particulate phase of cigarette MSS under metal-mediated conditions. An unidentified alkyl radical and the carbon dioxide anion radical were also observed nnder their experimental conditions. They concluded that the results of their experiment indicated that the major particnlate-phase free radical was a quinone/hydro-quinone redox system in a polymeric matrix and that the radical signal conld become associated with DNA. Unequivocal proof was not provided for these claims. 

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