Vapour emission control system is intended for analyzing the waste vapour gas for oxygen gas content. The system also includes the pressure transmitter which can monitor the pressure on the waste vapour line. This system consists of two cabinets ;a detector cabinet in which the pressure transmitter, oxygen sensor, flow alarm sensor, sample selector valve and purge valve are included, and the monitoring & alarm panel on which the alarm unit, oxygen indicator are provided. The detector panel in steel is installed on deck nearby the vapour manifolds and the monitoring & alarm panel is mounted in the cargo control room.