Dynamic correction of measurement errors in polymeric moisture sensors - by calculating correction factor from long term sorption behaviour of the sensor

摘要

Process for dynamic correction of measurement errors in polymeric moisture sensors comprises determining the long term sorption behaviour by determining a chronological mean value (Mi), using the mean value and the instantaneous measured value (xi) to calculate a correction factor (Ki) which is dependent both on the value (xi) and on the difference (xi - Mi) according to the equation Ki = A.x1(xi - Mi), whereby the parameter (A) has a value which is dependent on the material and the construction of the sensor and the chronological mean value (Mi) is calculated using the expression. Mi = (N.Mi-1 + xi)/n+1, in which (N) is the quotient of the simulated decay period (TA) of the sorption process and the cycle time (TT) of the measurement cycle. USE/ADVANTAGE - The procedure allows correction of measurement errors encountered when using polymeric moisture sensors for measurement of the moisture content of gases, esp. air e.g. in ventilation and air conditioning units, making use of the change in dielectric constant of the polymer w.r.t. changes in its moisture content. The procedure makes use of the long term sorption behaviour of the sensor, which is detectable and reproducible, and the method does not use complicating factors such as heating the sensor element in dependence on the measurement value to limit the water uptake e.g. as described in DE2851686 and DE3011525.