| 摘要 |
54,671IA A B S T B A C T INSTRUMENTATION AND MONITORING SYSTEMS EMPLOYING DIFFERENTIAL TEMPERATURE SENSORS A differential temperature sensor to monitor fluid level in a pressure vessel, has heated, split-well thermowells of duplex design, mounted to the sidewall of a pressure vessel and communicating through a penetration in the pressure vessel sidewall. Each probe has at least one parallel axial bore therein, a related, selected pair of probes receiving respective heater and temperature sensing elements. The temperature of the heated temperature sensor drops on contact with water, when the water level rises. The systems monitor the differential temperature outputs a plurality of such sensors monitor differential temperatures to produce alarm indications and perform verification and error checking of the sensor output indications. Duplex sensor embodiments permit toggling between different, selected such pairs of probes for online testing and verification of monitored conditions under automatic and manual controls, and with on-line substitution of complementary elements in the event of element failure. |
