LOW TEMPERATURE INSULATION FAILURE DETECTOR

摘要

1493124 Determining insulation failure SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ BV 12 Nov 1974 48882/74 Headings G1N(A) and (C) A device for detecting failure of thermal insulation of a cryogenic tank comprises a plurality of cell units each containing an ion-conducting material which changes its electrical conductivity on freezing and a pair of electrodes 4, 5 in contact with said material connected in a circuit for measuring ionic conductivity. Each cell consists of a small reservoir 9 in communication with a large reservoir 10 but thermally insulated therefrom by an element 6, e.g. of p.u.c., whereby the sensitivity of the cell is increased. The large cell compensates for any loss of ion-conducting material. The ion-conducting material may be a solution of common salt or copper sulphate in water or hydrates of organic compounds. The electrodes may be of different materials, e.g. zinc and copper so that the measuring current is internally generated. The cells are connected in series to form groups I-VI each with a respective indicator 31-36 which enables the location of a fault to be detected. The cells may also be arranged in concentric circles. In a further embodiment Figs. 3 and 4 (not shown) a cup-shaped electrode (46) is fitted in a gas and liquid-tight manner to a moulded thermal insulating element (41) to form the large reservoir.