Gas detector for sulphur hexafluoride decomposition products

摘要

The detector comprises a detecting electrode 2 having a predetermined quantity of a metal element, a solid electrolyte 3 containing ions of the metal element, a polarisation electrode 4 which does not transfer ions of the metal element, a second solid electrolyte 5 containing ions of the metal element and a reference electrode 6. A platinum supply electrode 1 is formed on detecting electrode 2 and a power supply 7 is reversibly connectable between the detecting and polarising electrodes. The metal may be copper, silver, lithium or sodium. In use, power supply 7 is connected to electrodes 2, 4 so that the metal (eg silver) in the solid electrolyte 3 is deposited on electrode 2 and, due to cation depletion in solid electrolyte 3 adjacent polarisation electrode 4, a potential Vao is set up between the polarisation and reference electrodes 4, 6. Detecting electrode 2 is exposed to decomposition products such as fluorine which attack the silver layer and change the resistance between electrodes 2 and 1. On detection of a resistance change, power supply 7 is connected in the opposite sense to retain silver ions from electrode 2 to solide electrolyte 3. The potential between electrodes 4 and 6 (Va1) is then measured and the difference between Vao and Va1 is a measure of the degree of decomposition. IMAGE