Simple, low-cost flow controllers for time averaged atmospheric sampling and other applications

Abstract

In air sampling is often necessary to limit the air inflow into an initially void vessel in order to extend the filling time. This requires devices characterized by very low, known and stable conductance. Likewise devices may also be used to control the gas flow between two vessels, or the outflow from gas containers. Depending on the use, they are called flow controllers, controlled leaks or, as in our case, inflow regulators. In this work we describe simple and cheap inflow regulators designed to collect air samples in 0.5 L vessels with filling times of many days. These inflow regulators may be adjusted within a wide impedance range and proved to be very stable under laboratory conditions and reasonably stable even under much harder operating conditions in field experiments.