Section 159(8) in The Coal Mines Regulations, 2011
(8)In every mine in which a mechanical ventilator is in use, the quantity of air shall, once at least in every 14 days be measured -(i)In every main intake and return airway of every seam or section, as near as practicable to the entrance to the mine;(ii)in every split, as near as practicable to the point at which the split commences;(iii)in every ventilating district, as near as practicable to the point where the air is subdivided at the end of a split and also where it enters the first working place; and(iv)any other point the Regional Inspector may, by an order in writing, specify,and the measurements shall be entered in a bound paged book kept for the purpose:Provided that in a non-fiery seam or a gassy seam of the first degree it shall be sufficient to take the air measurement once in every 30 days.
