USE OF SIEMENS KPY PRESSURE SENSORS AT LIQUID-HELIUM TEMPERATURES

Siemens KPY pressure sensors are evaluated for use at liquid helium temperatures. Sensor output for KPY-12 (2 bar range) sensors is approximately 2. 5 times greater at liquid helium temperature than at room temperature. Sensor output sensitivity varies by more than plus or minus 20% from sensor to sensor at both room and liquid helium temperatures. Sensor calibration in the He II range is frequently done by varying the vapour pressure over a saturated bath of helium in contact with the high pressure side of the sensor and with vacuum on the reference side. Since the temperature also varies in the above procedure, calibration errors would result if significant temperature-induced zero shifts occurred. To check on the above possibility, calibrations in which temperature and pressure were varied independently were compared with saturation curve calibrations. The two calibration procedures agreed within experimental error.