I worked in a new building with halon in the equipment rooms. It fired off once, causing great alarm but no harm.
A fire in the storage area, used to hold materials during the final phase of construction, was more dramatic.
A spare Halon bottle cooked in the fire, it vented, travelling about 100 yards through the air and into someone's bedroom via the wall.
The accident investigators were not amused when told that the cylinder was a fire extinguisher. The clerk of works was arrested until delicate negotiations secured a truce