A condensable, by definition, is a compound that when presented with a surface that is at a temperature below its dewpoint will form a condensate on that surface. This dewpoint temperature is also called as the equilibrium dewpoint (DPe). However, in the presence of time-varying temperatures and gas velocity, the temperature at which these compounds condense can be considerably lower than the equilibrium dewpoint. We call this the Kinetic Formation Temperature (FTk). And the temperature necessary to completely re-volatilize any condensed deposits will be higher than the equilibrium dewpoint. We call this the Kinetic Evaporation Temperature (ETk).
The AbSensor – SO3/AbS measurement device measures the phenomenon of condensable condensation on a highly polished glass surface with embedded electrodes. As the temperature of this surfaces approaches the FTk, material condenses and the temperature is recorded. As this temperature is raised, it passes through the DPe, that temperature is also recorded. And finally as the temperature exceeds the ETk temperature, the deposit is vaporized as evidenced by the lack of current and this temperature is recorded.