# The Fishing Vessels (Safety Provisions) Rules 1975, Paragraph 3


(a) Every self-contained breathing apparatus provided in compliance with these Rules shall be of the open circuit compressed air type.
(b) The storage capacity of the compressed air cylinder or cylinders attached to the apparatus and carried by the wearer shall be at least 1,200 litres of free air. The storage cylinders shall be constructed of suitable material and shall be of efficient design and of sufficient strength to withstand with an adequate factor of safety the internal air pressure to which they may be subjected, and each cylinder shall be capable of withstanding a test by hydraulic pressure suitably in excess of the maximum working pressure.
(c) Means shall be provided for the automatic regulation of the air supply to the wearer of the apparatus in accordance with his breathing requirements when he is breathing any volume of free air of up to 85 litres per minute at any time when the pressure in the supply cylinder or cylinders is above 10 kilogrammes force per square centimetre. Means shall be provided for overriding the automatic air supply valve.
(d) A pressure gauge with an anti-bursting orifice shall be incorporated in the high-pressure air supply system to enable the wearer to read directly and easily the pressure of air in the supply cylinder or cylinders.
(e) Means shall be provided for warning the wearer audibly when 80 per cent of the usable capacity of the apparatus has been consumed.
(f) The maximum weight of any such apparatus shall not exceed 16 kilogrammes excluding any lifeline and, if they do not form an integral part of the apparatus, any safety belt or harness.
(g) Every self-contained breathing apparatus shall be provided with fully charged spare cylinders having a spare storage capacity of at least 2,400 litres of free air except that:—
(i) if the vessel is carrying five sets or more of such apparatus the total spare storage capacity of free air shall not be required to exceed 9,600 litres; or
(ii) if the vessel is equipped with means for re-charging the air cylinders to full pressure with air free from contamination, the spare storage capacity of the fully charged spare cylinders of each such apparatus shall be of at least 1,200 litres of free air, and the total spare storage capacity of free air provided in the vessel shall not be required to exceed 4,800 litres.
(h) A servicing and instruction manual shall be kept with each such apparatus.

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Source: https://www.legislation.gov.uk/uksi/1975/330/schedule/23/paragraph/3 (the official version)
Page: https://openlegislation.uk/fishing-vessels-safety-provisions-rules-1975/schedule-23/paragraph-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.