Development of a fully automated soap flowmeter for micro flow measurements

Challenges in Microflow Measurements

“…The influence of soap properties on the flow measurement are discussed in the literature (Barigou and Davidson, 1994). (Lashkari and Kruczek, 2008A).…”

“…The new instruments are based on existing soap flowmeters, in which the bubble maker and the calibrated tube are modified (Lashkari and Kruczek, 2008A). Fig.…”

“…Fig. 2 presents a schematic diagram of an automated bubble-making device developed by Lashkari and Kruczek (2008A). In order to make the process fully automated, a computercontrolled three way solenoid valve, a needle valve, a low pressure regulator and a sealed soap container are used.…”

“…The actual holding time of the liquid inside tube depends on its size. For example, for a 500 µL flowmeter, 0.3 second was determined to be a sufficient residence time for the soap liquid in the tube to make a thin, yet strong layer of soap at the gas entrance (Lashkari and Kruczek, 2008A). It is important to note that such a short residence time would not be attainable if the bubble were made manually by squeezing a rubber bulb.…”

“…where Pe is the Peclet number ( The model for back diffusion and back permeation was compared with experimental data generated in single gas permeation experiments with oxygen and nitrogen using a homogeneous PPO membrane, in a CP system equipped with fully automated soap flowmeter capable of measuring the flow rates as low as 0.005 cm 3 /min (Lashkari and Kruczek, 2008A). The experimental system also allowed sampling of the permeating gas at three different distances from the membrane in order to compare the experimentally determined gas compositions with the model-predicted values.…”