Are there any differences between independent ventilation, parallel ventilation and zone ventilation in coal mines?

Independent ventilation means that the mine ventilation system is independent and is not interfered by other ventilation. Parallel ventilation is a method of ventilation in mines. Zoned ventilation is the process of dividing the mine into two zones and ventilating each zone independently.

Independent ventilation may consist of, one working main ventilator, or zoned ventilation (two working main ventilators). It is impossible for a mine to have parallel ventilation for the entire mine.