Surface supplied diving using a mixture of helium and oxygen as the breathing gas can be used to increase the range of surface diving operations without the use of saturation techniques. However, in general this technique is not intended to be used as an effective alternative to saturation diving.

This guidance document sets out the limitations of the technique and areas to be covered in dive plans.

In particular, the dive plan needs to consider all of the relevant safety implications of using this technique instead of a closed bell. The restricted bottom time in the deeper range results in it only being suitable for a limited range of work, such as short duration inspection dives or simple tasks, such as disconnecting a wire.

Revision 1 of the guidance, published in August 2005, follows a workgroup review undertaken by representatives of IMCA from each region which considered use of the technique in various locations, assessing the hazards and operational limits associated with such work and the issues to be considered during risk assessments to help ensure safe diving operations.