Abstract: A system and method are described herein that control the environment (e.g., oxygen, hydrogen, humidity, temperature, gas flow rate, pressure) around one or more vessels in a glass manufacturing system. In the preferred embodiment, the system includes a closed-loop control system and a capsule that are used to control the level of hydrogen around the exterior (non glass contact surface) of the vessel(s) so as to suppress the formation of gaseous inclusions and surface blisters in glass sheets. In addition, the closed-loop control system and capsule can be used to help cool molten glass while the molten glass travels from one vessel to another vessel in the glass manufacturing system. Moreover, the closed-loop control system and capsule can be used to maintain an atmosphere with minimal oxygen around the vessel(s) so as to reduce the oxidation of precious metals on the vessel(s).