Abstract: The invention provides a vent cap for automatically discharging a gas container such as a propane cylinder. The vent cap includes threads for securing the vent cap to the neck of the gas container. The vent cap further includes an indicator which has a pin and a button. When the button is manually depressed, the pin engages the valve stem of the check valve which seals the gas container, discharging gas from the container. The button includes a flexible, radially curved central portion which provides oil can action when the indicator is moved between the up position and the down position. A geometrical configuration of the central portion may be adjusted to vary the gas pressure threshold at which the indicator will remain in the down position to automatically discharge a nearly empty gas container.