A valve assembly includes a pipe fitting through which a gas is configured to flow. The inlet of the pipe fitting is configured to connect to an open port of a fire suppression sprinkler system so that gas flows from the fire suppression sprinkler system into the pipe fitting. The valve assembly also includes a vent valve. The inlet of the vent valve is connected to the outlet of the pipe fitting. The vent valve is operable to move between an open position and a shut position. The valve assembly includes an inert gas analyzer and at least one vent port upstream of the inert gas analyzer. The inert gas analyzer is positioned to measure the inert gas content of gas flowing in front of the inert gas analyzer and through the vent port to an outside environment.