The EX-5100 incorporates a pellistor or catalytic bead sensor. This sensor consists of a matched pair of elements, one active and the other for compensation. The active bead is coated with a catalyst that, when in contact with a combustible hydrocarbon or solvent, causes the gas or vapor to “burn” or oxidize at concentrations below the Lower Explosive Limit (LEL). This oxidization process raises the temperature of the active bead and increases the resistance of the internal wire coil. The second bead does not have the catalytic coating and provides compensation for environmental conditions including temperature and humidity. When these elements are connected in
a Wheatstone bridge type circuit, a useable signal is produced that is proportional to the gas concentration. The transmitter is 24 Vdc loop powered and provides a 4-20 mA output signal that can be connected to a controller, PLC or similar instrumentation.