Patent GB-257266-A (GB)
Title: Improvements in an observation window for furnaces
IPC: F23M7/00
Filed: 1926-08-17
Abstract: 257,266. Vastine Engineering Products Corporation, (Assignees of Vastine, R. P.). Aug. 24,1925, [Convention date]. Observation devices.- A plurality of separately movable e observation closures are arranged at the outer end of a passage associated with the furnace. Heat reducing means are arranged in the passage, air is circulated between the transparent closures and between spaced casings within the passage, and means may be provided for automatically cutting off the former air circulation when the closures are opened. The passage comprises an outer converging metal casing 1 with ribs 2 secured to and communicating with an opening in the furnace door and containing an inner ribbed casing 21 having a flange 6 bolted to a flange 3 on the casing 1 with the interposition of a spacing frame 5. Supports 7 integral with the rim 6 carry pivotally frames 8, 9 in which are mounted glass plates 37, 27. The lower end of the frame 8 is provided with lugs 36 for a spring fastening bolt 12 having a head 35 and passing through the rim 6, a spring 32 being fixed to the inner end of the bolt and bearing against the rim 6. At its lower edge the rim 3 is formed into a chamber 10 communicating with a chamber 14 to which is bolted a hollow cylindrical member 20 rotatably secured to an elbow connection 38 joined by a telescopic pipe to an elbow connection 41 rotatable in a member 42 fixed to the furnace wall. Air is supplied to the member 42 and passes through the chambers 14, 10, some of it then flowing rearwardly around the inner casing 21 and through a grid 24 at its end into the furnace, or through holes 26 into the casing 21 and through the grid 24 to the furnace. The rest of the air flows through an aperture 31 in the rim 6, passes between the glass plates 27, 37, through an aperture 28 at the top of the frame 9 to the inner side of the plate 27 and through a heat reducing grid 22 to the casing 21 and thence to the furnace. For natural or closed fire room draught the base 18, Fig. 6, of the chamber 14 is provided with an opening 19 governed by a balanced valve 16 light enough to be raised by the air pressure, while for the closed ashpit system the member 42 is connected with the ashpit. In a modification, Fig. 8, lugs 52 are provided at the lower edge of the rim 48 of the inner casing 50 for supporting a shaft 53 on which are pivoted inner and outer frames 54, 55 fitted with glass plates 54<1>, 55<1>. Spring fastening bolts similar to the bolts 12 secure the windows at the top and when they are closed the outer frame 54 abuts against pins fixed to a rod 68 so that the rod is forced away from a slot 67 in the rim 48. Air may then pass from the chamber 14 around the inner casing 50, through the aperture 67, between the glass plates 54<1>, 55<1>, through an aperture 64, past the inner face of the plate 54<1> and through a grid 51 to the furnace. When the windows are opened the rod 68 closes the aperture 67 preventing escape of hot air without stopping the flow around the inner casing. In the case of natural draught the flow of air is increased by removing plates such as 72 closing the gap between the rim 48 and the rim 47 of the outer casing 44.