The facilities regulations § 41a

§ 41a Evacuation and rescue means for manned underwater operations

Divers at pressure shall be able to be saved and evacuated to a safe area, cf. Section 77, literas c and d of the Activities Regulations.
Diving facilities shall at all times have available equipment such that personnel in chamber complexes, diving bells, subsea chambers and subsea vessels can be rescued in an emergency.
Assessments shall be made of the need for and choice of equipment for hyperbaric evacuation.
Systems for hyperbaric evacuation shall be designed so that the divers can be evacuated from the chamber complex using two independent units. Each unit shall be able to evacuate all the divers at pressure.
Hyperbaric evacuation units shall be designed so that they can be towed and raised or otherwise removed from the water under the weather conditions where such evacuation units are intended to be used.
Section last changed: 01 January 2014

In order to fulfil the diving facilities requirements as mentioned in the second subsection, Chapter 9-3 of the NORSOK U-100N standard should be used.
In order to fulfil the design requirements of hyperbaric evacuation units as mentioned in the fifth subsection, the NORSOK U-100N standard should be used, with the following addition: hyperbaric evacuation units should be able to be lifted out of the water using a single attachment point.
In order to achieve the necessary safety level for evacuation at sea using hyperbaric evacuation means, it is important to safeguard, amongst other, the following:
  1. The safety of personnel
  2. Structural integrity (structural safety)
  3. Sufficient propulsive and manoeuvring ability after launch
  4. Qualification, trials and testing, cf. Section 9 of the present regulations and Section 19 of the Framework Regulations.
For the design of flange connections, IMCA D 051 Hyperbaric Evacuation Systems (HES) Interface Recommendations should be used.