GB547840A - Improvements in pyrometers - Google Patents

Abstract

547,840. Electric thermometers. BRAYSHAW FURNACES & TOOLS, Ltd., BRAYSHAW, S. N., NEWMAN, F. C., and RUSHTON, F. Oct. 21, 1941, No. 13547. Addition to 543,597. [Class 97 (iii)] In an electric thermometer for measuring the temperature of a liquid bath of the type wherein the thermo-couple or resistance coil and the wires thereto are enclosed within a sheath, the sheath is surrounded by but separated and insulated from an outer sheath contacting with the liquid in the bath and means are provided whereby, on leakage of liquid into the inter-sheath space, an electric circuit is completed through an alarm and/or control and/or cut-out device. As shown, the thermometer comprises a thermo-couple or resistance A connected by the wires a<SP>1</SP> and a<SP>2</SP> to the terminals b<SP>1</SP> and b<SP>2</SP> in the head B, the thermo-couple or resistance A and the wires a<SP>1</SP> and a<SP>2</SP> being enclosed within a cylindrical sheath C, preferably made of steel. An outer sheath C<SP>1</SP>, preferably also made of steel, is insulated from the sheath C in the head B and at the bottom by an insulating ferrule c<SP>2</SP>, and the sheaths C and C<SP>1</SP> are connected by wires c and c<SP>1</SP> to terminals b<SP>3</SP> and b<SP>4</SP> in the head B. If the sheath C<SP>1</SP> is broken, molten metal flows into the space between the sheaths C and C<SP>1</SP> and establishes an electrical connection therebetween, thereupon causing the lighting of a lamp and the ringing of a bell in the external circuit connected to the terminals b, and b 4 , if desired through a relay circuit. In modifications, a wire is inserted into the intersheath space and the other connection made through the sheath C<SP>1</SP> or to the bath-container (if conducting), or two wires may be inserted into the intersheath space.