| 摘要 |
988,918. Detection of alkali metal fluids, detection of leaks in pipes. UNITED AIRCRAFT CORPORATION. Jan. 25, 1963 [Feb. 13, 1962], No. 3325/63. Headings G1B and G1S. A device for detecting the presence of alkali metal e.g. lithium, fluids in a gaseous stream or in a vacuum is characterised in that a tensioned metal wire or strip 16 e.g. of platinum is located in the gaseous stream or vacuum and is heated to a temperature lying slightly below the melting point of the metal, and that a material e.g. a sleeve of a silica compound 42, which reacts with the metal in the presence of alkali metal fluids to form an alloy which has a substantially lower melting point than the metal so that the metal wire or strip is broken whereby a signalling device is actuated. In the device of Fig. 1 a pipe 34 carrying liquid alkali metal is enclosed by a larger diameter pipe 36 containing air or an inert gas such as argon. If there is a leak in the pipe 34, the alkali metal will be carried to a housing 26 containing the wire 16 supported between conductors 12, 14 at least one of which is resilient to tension the wire 16, the wire being heated by passage of a current from a battery 22. The alkali metal will cause the silicon of the sleeve 42 to alloy with platinum wire 16 causing the wire to break on indication of this being given by the reading of an ammeter 24 in the wire circuit. The device may alternatively be positioned in the diffuser of a nuclear reactor turbine engine which is cooled by a ahthium filled radiator. In this case the wire 16 will be heated by the exhaust gases from the turbine, and in some cases the electrical heating circuit for the wire 16 may be dispersed with. Fig. 5 shows such an arrangement the device illustrated being adapted to make contacts 58, 60 in an alarm circuit when the wire 16 breaks. In Fig. 6 the platium wire 16 has several sleeves 42 of siliceous material and is tensioned by a spring 54 between rigid support conductors 50, 52. The wire 16 is disposed in a vacuum jacket surrounding the liquid metal carrying pipe 34. With several of the devices shown in Fig. 6 disposed along the pipe 34 it is possible to locate a leak in the pipe. |
