Abstract: A flow control apparatus for controlling the flow of a low pressure air stream in an air duct of an air ventilation system includes a conduit section having spaced upstream and downstream ports in upstream and downstream portions thereof, a redirecting member in the conduit section for redirecting air in the upstream portion thereof so that it passes outwardly through the upstream port, and a loose flexible membrane operable for redirecting air passing outwardly through the upstream port so that it passes back inwardly through the downstream port. The apparatus further includes an outer housing defining an enclosed chamber around the outer side of the membrane and a controller for controlling the air pressure in the membrane in order to selectively collapse the membrane around the ports in the conduit section. The controller is operative for controlling the air pressure in the chamber by selectively connecting the upstream end of the conduit section to the chamber and selectively bleeding air off therefrom.

Abstract: An industrial process recording instrument includes a roll chart cassette assembly that is readily removable from the instrument to accommodate replacement of the chart record. The replacement chart record is furnished on a supply roll insertable in one place of the cassette, while the lead end of the chart record is fixedly presecured to a take-up roll insertable in another place of the cassette, in such disposition that the longitudinal axis of the chart record is exactly perpendicular to the axis of the take-up roll. Thus the roll chart can be easily installed while the cassette is being hand-held in near-perfect alignment, thereby effectively minimizing the possibility of paper jams as the chart record is fed along the cassette.

Abstract: A vortex-shedding flow-sensing instrument comprising a flat-faced vortex-generating plate integral with a downstream sensor-bar having flat sides set back laterally with respect to the rows of vortices shed from the edges of the vortex-generating plate. The side surfaces of the plate are tapered inwardly at a moderate angle, and extend downstream a short distance to rear surfaces at right angles with respect to the direction of fluid flow. The downstream end of the sensor bar comprises a tail piece the side surfaces of which are tapered inwardly at a moderate angle, and extend downstream a short distance to a rear surface perpendicular to the direction of fluid flow.The sensor bar carries a liquid-filled capsule having as side walls a pair of flexible diaphragms effectively in the plane of the sensor-bar side surfaces. These diaphragms are of moderately large area so as to respond to a relatively large portion of the vortex energy.

Abstract: A matrix for plastic letterpress printing plates and the method of formation thereof are presented wherein the matrix material prior to molding is thicker than the desired molded matrix. The "non-printing" areas of the matrix are compressed to at least seventy percent of the density of the compressed "printing areas" in forming the matrix, and the matrix may then be ground to desired thickness to obtain desired heat transfer characteristics.