51.—(1) No person shall enter or remain in any confined space in any part of a vessel, being a confined space in which there is reason to apprehend the presence of any dangerous fumes to such extent as to involve risk of persons being overcome thereby, unless he is wearing a breathing apparatus of a type approved for the purpose of this Regulation, or a responsible person has certified the space as being, for a specified period, safe for entry without breathing apparatus, and the period so specified has not expired; but no person shall enter or remain in the space without breathing apparatus unless he has been warned when the period so specified will expire.
(2) A space shall not be certified under paragraph (1) of this Regulation unless—
(a)effective steps have been taken to prevent any ingress of dangerous fumes, and
(b)any sludge or other deposit liable to give off dangerous fumes has been removed and the space contains no other material liable to give off dangerous fumes, and
(c)the space has been adequately ventilated and tested for dangerous fumes and has a supply of air adequate for respiration;
but no account shall be taken for the purposes of sub-paragraph (b) of this paragraph of this Regulation of any deposit or other material liable to give off dangerous fumes in insignificant quantities only.
(3) Where any person is employed in any confined space to which paragraph (1) of this Regulation applies, there shall be provided and kept readily available—
(a)not less than two sets of breathing apparatus of a type approved for the purpose of this Regulation on board the vessel; and
(b)not less than two additional sets of such apparatus off the vessel; and
(c)a lamp or torch of a safety type approved for the purpose of this Regulation with each set of breathing apparatus; and
(d)not less than two belts and ropes suitable for the purpose of rescue.
The apparatus, belts, ropes, lamps and torches shall be maintained and shall be thoroughly examined, at least once a month or at such other intervals as may be prescribed, by a competent person; and a report on every such examination, signed by the person making the examination and containing the prescribed particulars, shall be kept available for inspection.
(4) A sufficient number of the persons employed shall be trained and practised in the use of the apparatus mentioned in the preceding paragraph of this Regulation and in a method of restoring respiration.