Abstract: he research concerns in the relationship between apparent pulsed amplitude and real pulsed amplitude for five systems of pulsed extraction column with air purge system. It is shown that the measured real pulsed amplitude is less than the calculated real pulsed amplitude derived from the ratio of the moving liquid volume in the pulsed leg to the sectional interface area of the extraction column without air purge system, and it is due to the air in the air purge system and extraction column is compressed.