sentences:  As with the piezoelectric and electrolytic sensors, the sensor is susceptible to interference from glycol and methanol, the calibration will drift as the sensor’s surface becomes inactive due to damage or blockage, so the calibration is reliable only at the beginning of the sensor’s life.In the second type (silicon oxide sensor) the device is often temperature controlled for improved stability and is considered to be chemically more stable than aluminium oxide types and far faster responding due to the fact they hold less water in equilibrium at an elevated operating temperature.Whilst most absorption type devices can be installed at pipe line pressures (up to 130 Barg) traceability to international Standards is compromised.