Olfactometry Flow Rate Criteria A Multiple Laboratory Study

The “odor presentation flow rate” or the “olfactometer flow rate” is the rate of airflow that is presented to the odor panelists from an olfactometer. The airflow rate from an olfactometer to the odor panelists contains the diluted odor sample or the blank air sample during presentation.In the U.S. the American Society for Testing and Materials (ASTM) Standard Practice E679-91, Determination of Odor and Taste Thresholds by a Forced-Choice Ascending Concentration Series of Limits, does not specify the “olfactometer flow rate”.The 1999 draft “European Standard”, prEN 13725, Determination of Odour Concentration by Dynamic Olfactometry, specifies an “odour presentation flow rate” of 20 liters per minute (lpm). The 1995 revision of the draft guidelines of the Air & Waste Management Association (AWMA) EE-6 Odor Committee, “Guidelines for Odor Sampling and Measurement by Dynamic Dilution Olfactometry”, recommends an “odor presentation flow rate” of between 5 and 10-lpm.A “Multiple Laboratory Study - Part I” was presented in 1997 at the Water Environment Federation (WEF) Odor & VOC Specialty Conference (Houston) [McGinley, et al, 1997]. In addition to presenting the background information of the subject, the Part I paper presented the testing protocol and the decision criteria for accepting an “odor presentation flow rate” standard. Specialists, experts, and practitioners in the field of olfactometry have commented and contributed to the study since 1997.Part II of the “multiple laboratory study” involved an analysis of the proposed “European Standard” and a rigorous effort to standardize laboratory practices of the participating odor laboratories, i.e. common panelist training. This paper presents some of the results of the flow rate study to date and offers recommendations for continuing interlaboratory testing.