GB1002297A - Improvements in or relating to fume cupboards - Google Patents

Abstract

1,002,297. Confining and removing fumes on generation. H. G. F. JENNINGS. Sept. 13, 1961 [June 14, 1960], No. 20843/60. Heading F4X. In a fume cupboard maintained at slightly less than ambient pressure by an extractor fan (not shown) drawing off from the operating shoot 9 via horizontal rear wall slots-21 and a duct 17, ingress of air to the chamber entry 31 is prevented or minimized by a gas curtain issuing through slots 39, 41 supplied by a fan (not shown) directly and via hollow chamber side walls respectively. This flow is preferably adjustable, e.g. by a damper in the fan inlet or outlet. The gas may be air or a gas which maintains an inert or reducing atmosphere in the chamber. As shown, the entry 31 has a sliding door 33 and the supply fan is energized before the door is opened. An alternative embodiment comprises a hollow door frame 61, Fig. 4, to be fitted against the outside of the front wall of the cupboard. Air is supplied through an inlet 89 and orifices 65 to two guides 63 and through two orifices 69 in the lower part of the frame to a lower guide 67, which is partitioned at 73, and is discharged through slots 83 and 87 across the opening. A sliding door 91, Fig. 5, comprises a frame 92 and air scoops 101 which fit into the slots 83. The door prevents outflow of air through the upper part of the slots 83 by means of the frame 92, and air which flows into the upper part of the guides is guided by the scoops 101 into a horizontal partitioned air duct 95 in the door, which discharges through a slot 99 to complete, with the previous discharge, a gas curtain across the door opening.