Seed NanoTech - Catalytic Bead Sensor

A catalyst present in the active bead allows combustible compounds to oxidize, thereby enhancing the heating of the bead even further and changing its electrical resistance. The result of the voltage difference between the passive and active beads is proportional to the concentration of all combustible gases and vapours present. The sampled gas can enter the sensor through a sintered metal frit, that provides a barrier to prevent an explosion when the instrument is carried into an atmosphere containing combustible gas. Pellistors measure all combustible gases, but they are more sensitive to smaller molecules that diffuse through the sinter more rapidly. The measurable concentration ranges are from a few hundred ppm to a few volume percents. Such sensors are robust and inexpensive, but require some minimum percentage of oxygen in the atmosphere to get tested and they can be poisoned or inhibited by compounds such as mineral acids, silicones, chlorinated organic compounds, and sulphur compounds.

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.