The question of homogeneity inside a chimney: application of ISO 13528 to stack emission proficiency tests

Abstract

The Hessian Agency for the Environment and Geology (HLUG) in Kassel, Germany, offers stack emission proficiency tests (PTs) on an in-house-constructed emission simulation apparatus (ESA). The PTs include gaseous (organic and inorganic) and particulate matter (heavy-metal-doped dust) emissions. A unique challenge arises when ISO 13528 is applied to these PTs: While homogeneity of the used gases, liquids, and dusts can easily be demonstrated, the equivalence of measurement points along the stack emission chimney is a completely different matter. Since each test item batch (in this case the pollution-doped ESA exhaust gas) only exists during one measurement, the standard procedure for determination of homogeneity (in this case equivalence of the sampling openings) is not applicable to determine compliance to the standard. To demonstrate the equivalence of the measurement points on our ESA, we devised a modified homogeneity check based on ISO 13528 annex B. This modified homogeneity check was successfully applied to our stack emission PT and should be applicable to sampling PTs in general.