For commercial diving using surface-supplied breathing gas, the bailout cylinder is in many cases required by health and safety legislation and approved codes of practice as an obligatory component of the diving system.

In this application the intention is that the bailout cylinder should hold sufficient breathing gas for the diver to be able to reach a place of safety where more breathing gas is available, such as the surface or a diving bell.
To achieve this the cylinder must contain enough gas to allow decompression if that is included in the planned dive profile and there is no bell.
Cylinder volumes are generally at least 7 litres, and may in some cases be as much as twin 12-litre sets.
Bailout sets used by closed bell divers must provide enough gas to return to the bell, and must fit through the bottom airlock door.
For commercial diving using surface-supplied breathing gas, the bailout cylinder is in many cases required by health and safety legislation and approved codes of practice as an obligatory component of the diving system.
In this application the intention is that the bailout cylinder should hold sufficient breathing gas for the diver to be able to reach a place of safety where more breathing gas is available, such as the surface or a diving bell. To achieve this the cylinder must contain enough gas to allow decompression if that is included in the planned dive profile and there is no bell. Cylinder volumes are generally at least 7 litres, and may in some cases be as much as twin 12-litre sets. Bailout sets used by closed bell divers must provide enough gas to return to the bell, and must fit through the bottom airlock door.
Bailout bottle