摘要 |
The tank (2) is in a corrodible material and has a detector for the appearance of water on the external surface (4) of the base of the tank. The cistern (1) may have an envelope (3) surrounding part of the external surface of the tank base. This envelope may define a watertight enclosure (5) between itself and the external surface. Alternatively, the external surface may be in an anhydrous atmosphere, or the enclosure may be full of an anhydrous fluid. The detector (7) may be attached by a detachable component, preferably a magnet. The detector signal may be amplified, e.g. by transistors, to indicate the appearance of water. The detector may be a hygroscopic salt bed, with electrodes and conductors (8,9) to an electrical circuit. |