Our Pellistor, or catalytic bead sensor, line is selected by N.E.T. and manufactured, on OEM basis, by the companies leading in the field.
The sensor monitors the presence of a combustible gas or vapor in air (or atmospheres containing oxygen) up to the Lower Explosive Limit (LEL).
A Pellistor operates on the principle that when a combustible gas/air mixture is in contact with the catalyst surface, maintained at about 500°C as current is passed through it in a Platinum coil, combustion occurs. The heat generated increases the temperature of the bead, which in turn changes the resistance of the coil. The resistive signal change produced is proportional to the gas concentration and can be measured by using the coil as a temperature thermometer in a standard Wheatstone bridge circuit.
Given Pellistors capacity to ignite flammable gas mixtures, is typically necessary to encapsulate the beads in a certified flameproof enclosure, such as N.E.T. Heads. This will allow the beads to be exposed to the target gas without the risk of ignition.