Olfactometry Project completed

The cooperation project of fiatec GmbH, Fraunhofer Institut für Bauphysik (IBP) and MANN+HUMMEL for determination of a more practical filter testing method as to disturbing odours and harmfull substances in passenger car cabins has been finished earlier this year.

The commonly accepted test methods up to now according to DIN 71460-2 and ISO 11155-2 are indeed cost-efficient but concerning the relevancy to practice, particularly with regard to the odour decreasing output of different agents, they have been frequently put into question. Consequently the cooperation partners were looking after a possibility to correlate the olfactometry tests with real test persons and odour tests with adsorption measurements in the laboratory on a few substances being comparably with regards to their characteristics.

As a first step the IPB identified large groups of substances on the basis of eight different automobiles conditioned in a shed chamber, from which the pilot substances to be tested were selected and a method of odour evaluation was established. For the following filter efficiency tests both odour threshold and odour intensity characteristics had to be defined for the selected substances and adequate test dimensions were chosen. After validation of the comparability of the olfactometry measurements and the adsorption tests by the means of one of the test substances (Hexanal), the IBP analysed the filters (or rather filter media), which were provided from MANN+HUMMEL, with the pilot substances on their efficiency. Afterwards the fiatec GmbH conducted the classical adsorption tests in the laboratory with odour active substances as well as with the substitutes Toluene and n-Butane.

The main result was that the olfactometry test method for evaluation of the filter performance is under certain circumstances applicable.

Also very important is the awareness that with the standard laboratory testing method the initial breakthrough or rather the olfactory impact after one hour of the particular test substance is crucial. Because in reality small odour changes over an extended time span can´t be perceived from humans („class room effect“) and the overall adsorption capacity has no observable importance for the performance in practice. Considering that circumstance the adsorption tests could at least for some of the substances show the odour decreasing effects.

Comparing the adsorption data of the pilot substances actually being present in passenger car cabins with the substitutes applied in the laboratory foremost Toluene reflected the adsorption performance of the pilot substances. N-Butane was in this context much less significant.

The detailed report you can find here in the download section. For further questions you can contact us per phone under 0049 9229 993919.