Section 165(1) in The Coal Mines Regulations, 2011
(1)Before any auxiliary fan is installed, and also, at least once every week thereafter, the quantity of air flowing in the airway at the point of its installation shall be measured by the ventilation officer:Provided that the fan shall not be installed or continued to be operated unless the measurement shows that sufficient quantity off air is available so that -(i)not more than 50% of total air passing in the roadway is taken by the auxiliary fan; and(ii)ventilation of the inbye faces when the fan is running is adequate.
