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Seed NanoTech - Photoionization Sensors
These detectors use a high-photon-energy UV lamp to ionize chemicals in the sample gas. If the ionization energy of the compound is below that of the lamp photons, an electron will be ejected, and the resulting current is proportional to the concentration of the compound. The broad range of compounds can be detected at levels that range from a few ppb to several thousand ppm. Some detectable compound classes in order of decreasing sensitivity include olefins, alkyl iodides and aromatics, amines, sulphur compounds, ketones, alkyl bromides, organic esters, aldehydes and alkanes, and organic acids. Photoionization detectors are beneficial because of their simplicity and excellent sensitivity. The major limitation with these detectors is that their measurements are not compound-specific. Photoionization detectors are widely used for industrial hygiene and environmental monitoring. They are usually bench-type, miniature, hand-held clothing clipped PIDs.
Gas sensors are devices used to detect the presence of gases in an area. Such sensors can be used to detect a gas leak or other emissions and can help shut down the process automatically by interfering with a control system. This is done in many different ways, one way is by sounding an alarm, which warns the operator in the area and indicates the location of the gas leak. What makes gas sensors so significant, is that they can detect gases that are harmful to organic life, animals, and humans.
Gas sensors are used mostly to detect flammable, combustible and toxic gases, as well as oxygen depletion. These sensors can be found in locations such as oil rigs, to monitor the processes of manufacturing, and are used emerging technologies such as photovoltaics.
Gas leak detection is the process in which potentially hazardous gas leaks are identified by sensors, and an alarm is sent off to inform people of the danger. Another way of detection is the visual identity that can be carried out by using a thermal camera.
Gas detectors are classified as per their mechanism of operation such as oxidation, semiconductors, photoionization, catalytic, infrared, etc. They are classified into many categories:
- Portable gas detectors are used to monitor the atmosphere around us, they are usually worn on clothing, a belt or harness. Such detectors are mostly battery-driven and they transmit warnings through audible and visible signals, such as flashing lights and alarms.
- Fixed types of gas detectors are used to detect one or more types of gases. Such detectors are mounted near the process area of a plant, in control rooms, or an area of interest, such as a bedroom of a residence. Normally, industrial sensors are installed on a mild steel structure that is rigid where continuous monitoring can be carried out.