Sensor purge is an automatic procedure that minimizes the drift at the wet end readings of the dew point measurement. The sensor is heated to a high temperature which evaporates all excess molecules out of the sensor polymer. This, together with autocalibration, results in a very small drift of the sensor due to the very linear behavior of the polymer technology.
By default, DMP probes perform sensor purge when they are powered on (known as startup purge), and at one day intervals (known as interval purge). If necessary, the purge settings can be configured with the Insight software, the Indigo80 handheld indicator, or using the Modbus protocol. However, Vaisala recommends leaving the sensor purge settings at their default values.
As with autocalibration, during sensor purge the values of the measurement parameters are frozen at their last measured values prior to the procedure.