If a simple comparison with lab measurement is not considered enough, a calibration piston, filled manually by the operator with the same process sample and validated by the lab can be foreseen. When the analyzer needs to be calibrated, sample is sent to fill a piston tank. While the tank is filling, a sample grab bottle mounted on the same calibration panel is flushed in order to have it filled with the same product. This bottle shall be brought to the lab for validation. By pressurizing the piston, the sample will be injected into the analyzer and calibration is then automatically performed.