| 摘要 |
A plug for insertion through the wall of a vessel filled with fluid to be monitored has an extension immersed in the fluid which has a pair of wire electrodes helically wound thereon in spaced arrangement. The electrodes are wound at a uniform pitch in one embodiment and wound with regions of closely and widely spaced pitches in another embodiment. In a third embodiment, the electrodes are helically wound in spaced parallel arrangement at a pitch greater than the spacing of the pair. A thermistor is disposed on the extension for providing a fluid temperature signal. The electrodes are excited sequentially by a low voltage at a fractional Hertzian (low) frequency and a Hertzian (high) frequency and the current and temperature are measured. The impedance and differential impedance are computed from the measured currents. From stored values of the differential impedance as a function of temperature for various known fluid conditions, the condition of the fluid is determined; and, if greater than a predetermined threshold, an alarm is activated and/or the fluid condition displayed. <IMAGE> |
