23.—(1) No person other than the deputy in charge of a district affected or an official of the mine authorised by the manager or a person authorised by such a deputy or official shall start, stop, remove or alter any fan installed below the ground at any mine.
(2) A deputy or official shall not start or authorise any person to start such a fan on any occasion unless the deputy or official is satisfied that it is safe for the fan to be so started.
24.—(1) No auxiliary fan shall be installed at any place in a mine unless the manager is satisfied—
(a)that the quantity of air reaching it at all times will be sufficient to ensure that it does not re-circulate air; and
(b)that air circulated by it will not be contaminated by any substantial quantity of any noxious gas or dust;
and no such fan shall be worked at any time at which either of those conditions is not satisfied.
(2) No auxiliary fan shall be installed at a point within, or less than fifteen feet from the nearer side of the entrance to, the place to be ventilated by it, so however that in the case of two or more fans installed in series this requirement shall apply only to one of them.
(3) Any forcing auxiliary fan shall be installed on the intake side and any exhaust auxiliary fan on the return side of the place to be ventilated by it.
(4) There shall be installed and maintained with every auxiliary fan such an air duct for conducting air to or from the face of the place to be ventilated as ensures adequate delivery of air within fifteen feet of the face and minimises leakage.
(5) Every auxiliary fan, whether driven electrically or otherwise, shall be so connected with earth as to prevent the accumulation of an electro-static charge.
25.—(1) In respect of every auxiliary fan at a mine the manager shall fix the minimum quantity of air to be delivered or exhausted per minute at the end of the air duct.
(2) The manager shall make and secure the efficient carrying out of a arrangements whereby at least once in every week a competent person appointed for that purpose by him measures the quantity of air being so delivered or exhausted and determines whether any air is being re-circulated by that fan.
(3) Particulars of the quantity fixed under paragraph (1) and of every measurement and determination made under paragraph (2) shall be recorded forthwith by the manager or the competent person, as the case may be, in a book provided for that purpose by the owner of the mine.
26.—(1) Two or more auxiliary fans shall not be installed in any section of narrow or panel workings so as to draw air from the same air current unless there is kept at the mine an accurate plan showing the general system of ventilation in that section and the quantity of air in each air current therein.
(2) Upon the preparation of such a plan the manager of the mine shall send a copy thereof to the inspector for the district, and if any change in the system of ventilation or any substantial variation in the quantity of air in any air current thus shown is made, the manager shall send an amended plan or otherwise give notice of the change or variation to that inspector as soon as the effect thereof can be ascertained.
27. Without prejudice to the generality of subsection (5) of section fifty-five of the Act, where a place is provided with an auxiliary fan, no workman shall enter or remain in that place while the fan is not operating unless the deputy in charge of the district or some other official appointed for that purpose by the manager has inspected the place and found it safe.
28.—(1) No fan (not being an auxiliary fan) shall be installed at any place below ground in a mine, unless the manager is satisfied that it is necessary or expedient to install it at that place for the proper ventilation of the mine, having taken into account a survey of the ventilation of every part of the mine which would or might be substantially affected and a report upon the appropriate type, size and location of the proposed fan, being a survey and report made by persons experienced in those matters appointed for the purpose by the owner of the mine or the manager.
(2) If any such fan is installed at any place below ground the manager shall forthwith give notice thereof to the inspector for the district, attaching thereto particulars of the survey and a copy of the report made in relation to that installation.