Oxygen Home Screen
Combustibles Home Screen
Probe Overview
Oxygen Depletion - ODel
Canaries were likely the first practical, industrial "Oxygen Depletion" sensors. They were used in coal mines for decades to indicate the presence of "combustibles" such as CO, Methane, etc. The canaries were generally replaced by emerging technology about 30 years ago.
Fuel Rich (reducing)
atmospheres can be
monitored directly
using a Zirconium Oxide cell placed in the radiant
zone of the combustion process. While this is typically thought of as the absence of oxygen,
inferring that O2 is non-existent, the opposite is actually true. Oxygen
molecules exist and can
be detected well into the
smoke.
Relative Scales for Oxygen, Combustibles and Odel
The magnitude of the voltage generated by a zirconium cell varies as function of cell temperature and difference in concentration of oxygen molecules across the substrate. This relationship is defined by an algorithm known as the Nernst Equation.
Zirtek offers a proprietary scale, ODel (Oxygen Depletion), as a unit of measure for operating in fuel rich atoms-pheres. ODel is derived directly from the Nernst Equation which gives ODel the same inherent quality as Volume % O2. This quality is not present in typical combustion Units of Measure. The Volume % Combustibles shown on the Zirtek Analyzer is derived from a carefully crafted scale based on data gathered in conjunction with a recognized leader in the combustion equipment industry using zirconium oxide technology. While this is a better representation of the firing conditions than component measurement (CO, CO2, etc.), it still is an empirical fit with a large void between conventional oxygen and combustible scales as shown above. ODel provides a cont-inuous, accurate measure for monitoring and/or control over a broad spectrum of firing conditions.