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.

 

Standard Calibration Coefficients

The Standard EX-5100 calibration is 0-100% LEL methane. Therefore, methane is considered to have a coefficient or relative response of (1.00) one. Calibration coefficients relative to methane have been generated for over 30 different combustible hydrocarbons and solvents. A partial list of these gases and vapors includes the following: Propane, Ethylene, Methanol, Xylene, Hexane, Pentane, Ethanol, Ethyl acetate, Butane, Ethane, Isopropanol, MEK, Hydrogen, Acetone, Toluene, etc.

 

In addition to the over 30 established coefficients, ENMET can generate calibration data for most common combustible gases and vapors for which a sample can be readily obtained.