GB695579A - Improvements in or relating to means for gauging or controlling humidity - Google Patents

Abstract

695,579. Automatic humidity control systems. P.A.M., Ltd. Nov. 27, 1951 [Nov. 27, 1950], No. 28955/50. Class 38 (iv). [Also in Group XXXVII] The humidity of a room or chamber is indicated and automatically regulated by means of an electric switch comprising a member formed for example of parchment, vellum or catgut, and capable of extension according to humidity. One end of the member is secured to a frame comprising a pair of parallel rods, and the other end operates a contact member, and spring means are provided to maintain the member taut. The switch controls valveamplifying means whereby an indicator and/or means for controlling the humidity are operated. Fig. 1 is an elevation of the device, Fig. 2 a sectional plan, and Fig. 4 a transverse section of the upper portion of Fig. 1. The extensible member 7 is fitted with metal clips 8, 9 at its ends, the lower clip 9 being attached to a forked member 11 with a threaded extension by which it is adjustably secured to a plate 2 connecting two parallel rods 1. At their upper ends their rods are screwed into a block 3, thus forming a rigid frame fixed to a support by bolts through a flange 4. At its upper end, the extensible member 7 is attached to a rod 10 which slides in a bore in the block 3 and is pressed upwards by a spring 18 to cause its domed upper end to engage a transverse member 20 with a contact 23 at one end. The other contact 24 is carried on a member 25 which is folded on itself and is secured by a screw to an L-shaped bracket 26. The position of the contact 24 is adjustable by a knob 33 and screw 29 engaging the bracket 26, which is split and provided with clamping lugs 31 to avoid backlash.. The knob bears a pointer 34 which moves over a graduated dial on a cup-shaped cover 36. The bracket 26 and the cover 36 are attached to the block 3 by studs 38, and means are provided for insulating the bracket 26 from the block 3 so that binding posts 40, 41 for external leads may be in separate electrical connection with the two switch contacts 23, 24. The frame formed by the rods 3, and the extensible member 7, are enclosed in an openwork casing 43 to prevent damage and to permit free access of air. The external circuit from the posts 40, 41 is connected to valve amplifiers and relays, preferably of the kind described in Specifications 618,169, [Group XIX], and 631,595, adapted to actuate an indicator and/or to control humidity regulating means. Initially the knob 33 is adjusted to provide a gap between the contacts 23, 24. If the humidity increases beyond the desired degree, the contacts engage to provide a compensating control. When humidity is maintained by supplying steam or atomized water, closure of the contacts interrupts the supply.