GB718708A - Improvements in or relating to indicating apparatus - Google Patents

Abstract

718,708. Thermometers. TAYLOR INSTRUMENT COS. July 16, 1951 [Aug. 8, 1950]. No. 16836/51. Class 97(3) [Also in Groups XIX and XXIX] An indicating, recording and pneumatic retroactive control system in (see Group XIX) may be applied to recording the temperature of material in a tank 65, which temperature may be maintained at a set point by a supply of steam controlled by a diaphragm valve 67 operated by compressed air, the temperature being sensed by a thermosensitive medium in a bulb 69 connected to a Bourdon tube 71 of a transmitter system TR. Compressed air at uniform pressure is supplied from a pipe 78 through a restriction 79 to a nozzle 77 where it escapes under control of a baffle 76 positioned by the Bourdon tube 71 to vary the back pressure in the nozzle to which a relay valve 80 responds to vary the output pressure in a pipe 81 which is fed back to a bellows 75 to reduce the movement of the baffle 76 due to a temperature change and, over a useful span, cause the pressure in the pipe 81 to be proportional to the temperature. The pressure in the pipe 81 is fed to a pneumatic motor 13 and operates a pen arm 9 to draw a time-temperature graph on a chart and indicate the temperature against a scale.