A new, simplified approach for filling air sampling canisters during monitoring of Environmental pollutants in air is described. The new approach uses helium diffusion to drive the sampling process in a way that has several advantages over vacuum sampling. Canisters are filled with helium after cleaning, using a valve and inlet fitting combination that allows the proper time integrated sample to be collected simply by removing the valve and allowing helium to leak out through a calibrated orifice. Orifice sizes are available for performing a range of integration times from 3 hours to 1 month, without the need for an external flow controller. Elimination of the flow controller from the flow path reduces sample loss, prevents contamination from previous sampling events, greatly increases simplicity and reliability of the sampling process, and increases the molecular weight range recoverable to include Semi-Volatile compounds. Utilizing HDS™ can also reduce the potential for contamination during field and lab leak checking. Data is presented detailing the advantages of HDS™, including comparisons with vacuum sampling canisters to show precision and sampling consistency.
|Improving Canister Sampling Accuracy and Reliability Using Helium Diffusion Sampling into Silonite Coated Stainless Steel Canisters||Download |