How it works: 1. Cool the soda machine cylinder in the freezer for 1 hour. 2. Attach the CGA320/W21.8 connector to a commercial CO2 gas cylinder. 3. Disconnect the quick connector of the black adapter, then securely tighten the black adapter to the CO2 cylinder. Ensure the knob on top of the black adapter is in the highest position. Do not press down the adapter knob during installation, as this may engage the 6mm valve pin and close the valve, preventing CO2 flow. 4. Reconnect the quick connector. 5. For larger CO2 cylinders without an internal dip tube (syphon tube), position the cylinder horizontally or upside down during use. 6. Slowly open the valve on the large gas cylinder. Opening too quickly may cause the internal protection valve to close due to excessive flow. Open carefully until a steady airflow is heard. 7. After approximately 15–20 seconds, the cylinder will be fully charged. 8. Close the valve on the large gas cylinder. 9. Open the bleed screw to release any remaining pressure. 10. Unscrew and remove the CO2 cartridge. Notes: - If liquid CO2 is present and refilling fails with the tank upright, invert the tank if it lacks an internal dip tube. - The cylinder must be empty before refilling. Pre-cooled cartridges allow for maximum fill. - Open the tank valve slowly to avoid triggering the 6mm protection valve on the soda machine bottle. - This adapter is not compatible with residual pressure valve (RPV) systems. Refer to the included image for identification. Some RPV valves can be removed using a hex wrench—verify your cylinder type before ordering. If your tank has an RPV valve, select the "RPV pushing adapter" option at purchase.