Low-flow purging

Puls, R. W., and Paul, C. J. (1995). Low-flow purging and sampling of ground water monitoring wells with dedicated systems. Ground Water Monit. Rem. 15(1), 116—123. 

Shanklin DE, Sidle WC, Ferguson ME (1995) Micro-purge low-flow sampling of uranium-contaminated ground-water at the Femald environmental management project. Ground Water Monitor Remediat 15 168-176... 

In pressure-swing processes, it Is quite common to use a fraction of the less-adsorbed gas product as a low-pressure purge gas, as shown In Figure 2. Often the purge flow is in the opposite direction from the feed flow. Rules for the minimum fraction of less-adsorbed gas product for displacing... 

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

Stabilization parameter bailing Low-flow micro-purge... 

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.)... 

Purge method Bailing Q High speed Q pump Low-flow Q micropurge ... 

Measurement and control of low-flow rates are a requirement in such applications as fuel cells, purging, bioreactors, leak testing, and controlling the reference gas flow in chromatographs or in plasma-emission spectrometers. The most traditional and least expensive low-flow sensor is the variable-area flowmeter. It has a high rangeability (10 1) and requires little pressure drop. Due to its relatively low accuracy, it is limited to purge and leak-detection applications. 

The level of the water in a well is measured to provide data for groundwater flow direction calculations and to calculate purge volumes required for a particular well. If a low-flow sampling protocol is used, the water level is also measured during pumping to ensure that there is minimal drawdown of the stagnant water column. 

Research by Barcelona et al. (1994) confirmed that low-flow-rate purging (i.e., 1 litre per minute) is a valid technique for 2" (5 cm) diameter monitoring... 

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