GB686594A - Improvements in radiation pyrometry - Google Patents

Abstract

686,594. Pyrometers. LEEDS & NORTHRUP CO. July 25, 1949, No. 19524/49. Class 97 (iii). [Also in Group XL (b)] In a radiation pyrometer in which comparison, of the intensity of radiation of two different wavelengths gives an indication of the temperature, two sensitive devices are provided, each responsive to one of the wavelengths the voltage output of each, for wavelengths whose reciprocals differ by more than unity when measured in microns, being compared. As shown, radiation from the furnace passes through a quartz lens 15 and wavelengths of less than 6000 A are imaged by a lightly gilded mirror 60 on to radially arranged thermocouples 17. Shorter wavelengths pass through the mirror and are brought to a focus in the plane of the filament 51 of a disappearing filament pyrometer which may be of the type described in U.S.A. Specification 1,362,281. The intensity of radiation is reduced by screens 56, 57 of blue green or purple glass and screens 58, 59 in the eye-piece approximate a green glass. The current in the pyrometer may be adjusted by a rheostat 53. The circuit arrangement is shown in Fig. 4, the thermocouple arrangement having the reference 19. Adjustment of ganged contacts 32, 34 maintains the total resistance external to the disappearing filament pyrometer 50 and its rheostat constant and the voltage developed by the filament current is balanced against output of the thermocouple 19 through a mechanical relay 62 which adjusts the slide wire contacts and drives a pen 68 over a chart. This mechanical relay may be as described in U.S.A. Specification 1,935,732. In a modification, Fig. 1 (not shown), the disappearing filament pyrometer is replaced by a barrier layer cell, and a galvanometer may replace the mechanical relay.