| MSHA's Accident Prevention Program
Mandoors in Coal Mines
Doors or mandoors are placed in the stoppings at certain intervals to allow miners access to other areas of the mine.
Sometimes it is necessary to deliver materials for roof support in bad top, damaged pump discharge lines, etc. to areas of the mine inaccessible to mobile equipment. Many times when this happens, the materials are carried through mandoors. This can adversely diminish the quantity of fresh air needed in other areas of the mine because the air short-circuits through the open mandoor. It is important to maintain compliance with the mine's ventilation plan by never leaving the mandoor open any longer than necessary to travel to the other side. All persons working in areas that may be affected should be informed prior to delivering the materials.
To minimize short-circuiting air through open mandoors:
Delivering materials through a mandoor should be done during non-production times as much as possible. If the mandoor location becomes a material delivery and distribution site used on a continuing basis, the check curtain should be replaced by another stopping with a door to form a permanent airlock.