The Semi-Automatic gas change over helps to do the changeover of one cylinder bank to another cylinder bank, This is done with the help of two pre-set regulator with differential pressure on both the side Pressure decrease in the active cylinder below the set level cause change over to full cylinder. The Liver moving towards the full cylinder bank helps of the disconnection and changeover of empty cylinder bank with the gas flow without interruption. The contact gauge or pressure transmitter used in the Auto gas changeover with low gas alarm panel helps to facilitate the alarm as per the pressure set on contact gauge or pressure transmitter.