A fire protection sprinkler system includes a water source, a sprinkler, a piping network interconnecting the water source and the sprinkler, and an automatic gas vent coupled to the piping network and configured to discharge gas from the system. The automatic gas vent includes a sensor configured to sense a presence or absence of a liquid and an electrically operated valve. The automatic gas vent is configured to open the electrically operated valve in response to the sensor sensing the absence of a liquid and close the electrically operated valve in response to the sensor sensing the presence of a liquid. Automatic gas vent assemblies and methods of venting and discharging gas from fire protection sprinkler systems are also disclosed.