Micro-purge technique

Low-flow minimal drawdown or micro-purge technique... 

Remove the pump from the well. (If not sampling with a bailer, go to Step 5 of low-flow micro-purge technique, described below in Chapter 3.6.2.4.)... 

There are two good techniques for measuring SGs of fine powders helium pycno-metry and XRD. Accurate and reproducible values have been obtained on a Micro-meritic s 1305 Multivolume Pycnometer. However, given the submicron size of most of the powders, careful calibration, sealing, and extensive purging cycles (>50) are needed before the true values are asymptotically approached. 

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