The main criticalityfor the purposes of putting the gas into the network (including biomethane)concerns their odorisation. In fact, for domestic and transport purposes, gasesmust possess precise olfactory characteristics to guarantee the safety ofusers. Determining the correct degree of odorization is paramount. Thisactivity is carried out within a rhinoanalytic chamber, as specified by the UNI7133-3: 2019 standard "Odorization of gases for domestic use and similar -Part 3: Procedures for defining the olfactory characteristics of odorousfluids". The rinoanalysis is the only recognized technique to verify thecorrect odorisability of the biomethane, according to the UNI 7133-2: 2019 "Odorization of gases for domestic use and similar - Part 2: requirements, control and management".
The LOD rinoanalyticalchamber, where the analyzes are performed, consists of a room of about 16 cubicmeters, covered in aluminum, inside which a known quantity of odorant hasevaporated and is mixed with the gas to be tested. Selected and trainedexaminers (rinoanalysts) pass through the chamber and record their olfactorysensation according to the DecaSales scale. The results must be compared with thereference data for the odorization.
In the case ofbiomethane, a sample is considered suitable for placing on the network if:
- Thesmell intensity is greater than or equal to 4 olfactory grades of the DecaSalesscale;
- The conformity of the type of odor is recognized by at least 85% of theexaminers participating in the essay (minimum six).
The LOD rinoanalyticlaboratory is the only one in Italy to be equipped with both an olfactometricchamber, according to UNI EN 13725: 2004, and a rhinoanalytic chamber,according to the UNI 7133-3: 2019 Standard. It is therefore the only one ableto carry out analyzes in parallel and to correlate the data collected accordingto the two methods.
LOD also has the necessary skills to perform specific studies on potential interferents to the correct odorization of biomethane (such as limonene, pinene and butanone).