Abstract: A mechanism is provided for operating multiple air flow control valves from a single actuator. The mechanism includes a yoke mounted to move with the drive shaft of the actuator and having a leg facing in the direction of each valve. The leg is resolvably connected, preferably by a link pivotably connected at each end, to a lever connected at its other end to a control shaft for the valve.

Abstract: An apparatus for sensing the extent to which the opening of a fume hood is uncovered by the hood sashes, and is particularly adapted for use with hoods having sashes which are moved horizontally. Radiation from a radiation emitter, such as an optical or a magnetic emitter, are sensed by corresponding detectors. For some embodiments of the invention, there is relative movement between the emitters and detectors as the sashes are moved to cover or uncover the opening, the movement between the emitter and the detector being such that the amount of radiation detected by the detectors is proportional to the uncovered portion of the opening. The relative movement may be accomplished by, for example, having the detectors fixed and having the emitters mounted to the sashes or by having the detectors mounted to some sashes and the emitters mounted to other sashes. A unique magnetic emitter is also provided with enhanced flux throw.