Abstract: A gas flow measuring device comprising a flowtube, a soap bubble generator for generating a film of soap, a manually adjustable member for controlling the transfer of the soap film to the flowtube and a set of detectors spaced apart along the flowtube for measuring the time displacement of the soap bubble between the spaced positions of the detectors. The manually adjustable member is preferably a hoop surrounding the flowtube. A soap bubble is formed by immersing the hoop into the soap solution and withdrawing it. A soap film is transferred to the flowtube by raising the hoop to the mouth of the flowtube. In a second embodiment, a sleeve with slots surrounds a flowtube with slots. The sleeve is rotated into alignment with the flowtube to transfer a soap film.

Abstract: A soap film gas flowmeter comprising a hollow flow tube having opposite open ends through which a soap bubble is propelled with one open end extending into a first closed chamber housing the soap solution and the opposite open end extending into a second chamber. Inlet gas is fed into the first chamber, passed through the flowtube and discharged from the second chamber. A manually movable piston like member is provided for generating a soap bubble at the bottom open end of the flowtube. The flowtube has an opening in it for providing an open passageway for inlet gas to pass through the flowtube when the bottom open end of the flowtube is covered by the soap solution.