fire damper

Noun

 * 1) A passive fire protection product used in heating, ventilation, and air conditioning ducts.
 * 2) A damper which closes off an air duct automatically in the event of fire so as to restrict the passage of fire and smoke.
 * 3)  A mine worker who detects and clears a mineshaft of firedamp by intentionally burning or blowing it up.
 * Jack is a former fire damper who was injured in an explosion.