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 adjustment rod, as this may close the valve and prevent CO2 from entering. 4. Reconnect the quick connector. 5. For larger cylinders, position the cylinder upside down or horizontally if it does not contain a dip tube (syphon tube). 6. Slowly open the valve on the large gas cylinder. Opening too quickly may cause the internal safety mechanism to restrict gas 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: 1. If liquid CO2 is present, invert the CO2 tank during use if refilling fails while upright, as some tanks lack an internal dip tube. 2. The cylinder must be empty before charging. Pre-cooled cartridges fill more effectively. 3. Open the tank valve slowly when charging to avoid triggering the 6mm safety pin mechanism in the soda machine bottle. 4. This adapter is not compatible with residual pressure valves (RPV). Refer to product images for details. Some RPV valves can be removed using a hex wrench—verify your valve type before ordering. If your tank has an RPV, select the "RPV pushing adapter" option at checkout.