BS EN 13725:2022

This document specifies a method for the objective determination of the odour concentration of a gaseous sample using dynamic olfactometry with human assessors. The standard also specifies a method for the determination of the emission rate of odours from stationary sources, in particular: - point sources (conveyed or ducted emissions); - active area sources (e.g. biofilters); - passive sources. The primary application of this standard is to provide a common basis for evaluation of odour emissions. When this document is used for the determination of the odour concentration or the odour emission rate of stationary source emissions, the other relevant European Standards concerning stationary source emissions apply, in particular EN 15259 and EN 16911-1, especially when measurements have to be in compliance with the relevant European Directives concerning industrial air emissions. Even so, the analysis/quantification step of the measurement method described in this document (i.e. the determination of the odour concentration of an odorous gas sample, without respect to the origin of the sample itself) can be fully applied in many cases not related with industrial emission sources (e.g. the measurement of the mass concentration at the detection threshold of pure odorous substances, the determination of effectiveness of deodorizing systems for indoor air). In those latter cases, the requirements in this document concerning the measurement planning and the sampling of stationary sources can be ignored or adapted. This document is applicable to the measurement of odour concentration of pure substances, defined odorant compounds and undefined mixtures of odorant volatiles in air or nitrogen, using dynamic olfactometry with a panel of human assessors being the sensor. The unit of measurement is the European odour unit per cubic metre: ouE/m3. The odour concentration is measured by determining the dilution factor required to reach the detection threshold. The odour concentration at the detection threshold is by definition 1 ouE/m3. The odour concentration is then expressed in terms of multiples of the detection threshold. The range of measurement is typically from 101 ouE/m3 to 107 ouE/m3 (including pre dilution). The field of application of this document includes: - the measurement of the mass concentration at the detection threshold of pure odorous substances in g/m3; - the determination of the EROM value of odorants, in mol; - the measurement of the odour concentration of mixtures of odorants in ouE/m3; - the measurement of the emission rate of odorous emissions from point sources, active area sources and passive area sources, including pre dilution during sampling; - the sampling of odorous gases from emissions of high humidity and temperature (up to 200 °C); - the determination of effectiveness of end-of-pipe mitigation techniques used to reduce odour emissions. The determination of odour emissions requires measurement of gas velocityto determine the gas volume flow rate. The field of application of this document does not include: - the measurement of odours potentially released by particles of odorous solids or droplets of odorous fluids suspended in emissions; - the measuring strategy to be applied in case of variable emission rates; - the measurement of the relationship between odour stimulus and assessor response above detection threshold (perceived intensity); - measurement of hedonic tone (or (un)pleasantness) or assessment of annoyance potential; - direct measurement of odour exposure in ambient air. For this measurement purpose, field panel methods exist which are the subject of CEN standard EN 16841-1, Ambient Air - Determination of odour in ambient air by using field inspection - Grid method; - direct olfactometry, including field olfactometry; - static olfactometry; - measurement of odour recognition thresholds; - measurement of odour identification thresholds. .....