The Exner EXtract 811 is a pneumatically operated retractable probe housing to be attached on process tanks or tubing with an extended immersion length up to 207mm. The drive unit inserts the sensor into the process medium and back into the cleaning chamber. When reaching the final position of “measuring” or “service”, the probe housing responds automatically by a pneumatic position signal. Cleaning, rinsing and calibration of the sensor is possible while the process is running.