ABSTRACT A new, simplified approach for filling air sampling canisters during personal monitoring of work place airborne chemicals is described. Helium Diffusion Sampling Personal Monitors (HDS-PM) are filled with helium and a surrogate after cleaning. Proper time integrated sampling is performed simply by removing the valve and allowing helium to leak out through a calibrated orifice, which simultaneously draws in the same volume of air. Orifice sizes are available for performing a range of integration times from 15 minutes to 8 hours, without the need for an external flow controller. A description of the technique is provided, including data showing that this is just another means of performing active TO15 sampling and analysis, as no diffusion based variances between light to heavy compounds were detected.
Helium Diffusion Sampling for Personal Monitoring by EPA Method TO15 App Note