Clairair's technology includes a wide range of sensing techniques including optical, catalytic, solid state, photochemical, ion and thermal methods. We make extensive use of 3D CAD, multilayer PCB and software compilers in developing products.
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As an independent sensor company we understand customers sometimes need a customised approach for a sensor, a circuit or a software application. We are pleased to provide a custom service to meet such requirements.
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The application of various sensing techniques leads to an ongoing program of product development. Clairair gas sensor products are backed up with extensive applications support.

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Catalytic Gas Sensors

Catalytic gas sensors, otherwise known as "Pellistors" have been used for detecting explosive levels of combustible gases for many years. They typically comprise a ceramic bead built around a platinum coil that serves as a heater element and a resistance thermometer. Pellistors are formed from a pair of such beads; one is catalysed in order to combust gas and forms the detector, the other is passivated to form a reference. The beads are connected in series and power is applied through the pellistor coils to heat the beads to a typical operating temperature of 500C. Any combustible gas contacting the hot catalyst combusts, releasing heat of oxidation and raising the resistance of the internal platinum coil. With the beads connected in a Wheatstone bridge arrangement this generates an out of balance voltage which is the measure used to relate to the level of combustible gas present.

Many different forms of pellistor exist: Standard (typically hard bead with an outer catalyst skin), poison resistant (typically porous beads with catalyst impregnated throughout) and special (catalysts optimised for combusting certain gases).

Clairair pellistors are grown in a purpose built facility in Essex, UK, using automated bead buildup equipment and automated test equipment.

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