Abstract: A positive displacement piston flow meter for measuring air flow comprising a hollow flowtube, preferably arranged in a vertical orientation, having a movable piston disposed in the flowtube for movement between a starting position, preferably at the bottom end of the piston stroke, and an elevated position at the top end of the piston stroke. The piston is reciprocated by means of a pressure relief control valve assembly which controls the ascent and descent of the piston. The piston is physically connected to the pressure relief control valve assembly by means of a flexible string, which causes the piston to automatically close the valve assembly for automatic operation on reaching the bottom end of the piston stroke and to reverse direction.

Abstract: The reciprocating piston positive displacement flow meter of the present invention comprises a hollow flow tube having a movable piston for reciprocal movement between opposite ends and a solenoid controlled valve assembly having a sliding valve member for reversing the direction of fluid flow through the flow tube in response to the activation and deactivation of a solenoid. The solenoid is switched from an activated state at one end of the piston stroke to an unactivated state at the opposite end.

Abstract: An electrically driven double-acting diaphragm air pump having a diaphragm-driven system including an eccentric for the motor shaft, a freely movable yoke having a solid framework solely supported by the diaphragm system with one end connected to a first diaphragm assembly, and at an opposite end to a second diaphragm assembly, and with the yoke having a large central opening. The eccentric is coupled directly to the solid framework through a yoke driver. The yoke driver is rotatably connected to the solid framework at one end of the framework adjacent to the first diaphragm assembly, and is coupled to the eccentric through ball bearings, with the opposite end of the yoke driver suspended for free movement within the large central opening of the solid yoke framework.

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.