7th Meeting to review the European Standard EN 13725

 en13725 meeting barcelona 26-27 Jan 2015

    The existing standard EN 13725, first published in 2003, requires revision. The 7th meeting of the group that deals with the revision of the EN 13725 just took place in the very nice city of Barcelona. The document is being written slowly, almost paragraph by paragraph, but very steady and thoroughly. With a frequency of 2-3 meetings per year, I think the document will be ready being optimistic around 2017, but this is a personal statement here.

   Taking into account that the first meeting took place in November 2012, I think that the rhythm is very steady although there are several key issues that are being left to the end due to the lack of information in some cases or in other cases due to a conflict between points of view.

 The initial 267 documents of information has grown to almost a hundred norms, a few hundreds of papers, notes, presentations and communications.However, it seems that it will be necessary to do quite a bit of research during the time-line of development of the Norm.


   After the Adoption of the minutes of the 6th meeting that took place in June 2014 in  Copenhagen, some issues about formal and operational standardization were discussed in things related with the scheduled work on odour in VERA. Also an EC/EFTA Mandate has been requested in order to obtain some financial resources for a programme that might include some items such as the validation of the method of sampling of odourant emissions from passive surfaces, the panel selection using a new complex odour reference mixture and the calculation of the uncertainty of the entire method for emissions measurement, including sampling and olfactometric analysis, for a ducted emission.

   In this meeting, the on-going work of some Tasks Groups (TG)* was reviewed. There was plenty of discussion in the TG1 about sampling bags and also about the best materials for use in an olfactometer. The preliminary results of an on-going research has shown that glass and not-coated stainless steel may not be proper materials for an olfactometer, at least for samples where H2S is involved. Anyway in my opinion these are preliminary results that have to be examined carefully.

   Also a proposal from M. Paduch was discussed again. The idea behind was to make clear distinction between intensity and concentration of odours that quite often is very misunderstood. The dependence of both parameters can be described as a theoretically derived logarithmic function according to Weber and Fechner:

Weber Fechner relation

   where C0 is the threshold concentration; and kw is the Weber-Fechner coefficient or Weber ratio.

   This kw is not usually easy to obtain and need quite a bit of research to get it for different odourants.

   The example of a paper by T. Missebrook et al. in 1993 was presented as an example. For an emission level of let's say 500 ouE/m3 a very annoying smell for a broiler house will be observed but on the other hand for pig slurry, barely a detection of smell might be noticed. This is quite relevant if we take into account that some institutions take an odour concentration limit as a set point for odour control technologies and maybe a different approach should be considered here.

 Anyway it was decided to include in the text that odour intensity is out of the scope for this Norm.

 A review of Dutch research papers about mass transfer rates between different chemicals on open top tanks was presented. The results showed little correlation in many cases as compared to the physical equations that describe this transfer, so looks like more research is needed here.

  Some Health and Safety issues were considered carefully in order to protect both the sampling team and the panellists that work in the lab. Additionally, a document that includes the sampling procedures of the German and the Dutch norm was released. No decisions were made anyway on this point at this stage.

 It was very nice to meet the colleagues in this very well organized event with odournet as a host institution this time. Barcelona is a beautiful city and the weather was great so I think we all enjoyed a wonderful stay there.




Misselbrook, T.H., Clarkson, C.R. and Pain, B.F. 1993. Relationship between concentration and intensity of odours for pig slurry and broiler houses. J. Ag. Engng. Res. 55(2):163-169.


*Task group formed for this revision:
Task group 1 Sample storage and materials for olfactometry
Task group 2 Reference material for panel selection and panel management procedures
Task group 3 Sampling of passive area sources (without flow)
Task group 4 Sampling of active area sources (biofilters)
Task group 5 Dynamic dilution during stack sampling
Task group 6 Implications of EN 15259 air quality - measurement of stationary source emissions and
other relevant sampling standards
Task group 7 Calculation of uncertainty
Task group 8 Compatibility of Yes/No and Forced Choice methods
Task group 9 Health and safety issues.