Volume measurement based on dynamic differential pressure decay using AAO leak element

A new technique to measure the volume of the metal container based on dynamic differential pressure decay by using anodic aluminum oxide (AAO) leak element is presented. The AAO is chosen as the leak element because its conductance remains constant from vacuum to atmosphere. The container to be measured is connected to the vacuum system via the AAO leak element. The dynamic differential pressure decay with time between the inlet and outlet of AAO leak assembly was measured and fitted by an exponential function, followed by volume calculation. The volume of two different containers has been obtained using this method with nitrogen, helium, and argon, respectively. The influence of temperature fluctuation on experimental results under vacuum and atmospheric pressure outlet conditions was discussed. For vacuum outlet conditions, the temperature change caused by pressure decay in one single experiment is small enough to satisfy the isothermal hypothesis, which makes the influence of temperature fluctuation on the experimental results negligible. The preliminary results compared with the static expansion method demonstrate that this novel volume measurement technique is accurate, simple and efficient. (C) 2019 Elsevier Ltd. All rights reserved.