It said "a more proactive maintenance and inspection regime" should have been in place to ensure that the door functioned efficiently and that its self-closing mechanism worked properly.
The committee examined long-term fire safety provisions, including enhanced training, inspections and additional retrofits such as sprinklers and self-closing doors.
By this means the valve seat was forced against the valve by the water pressure, producing a self-closing action, so that the greater the water pressure, the tighter the valve.