Why should the diluent cylinder of a CCR be full at the start of a dive?
The diluent may be used for suit inflation and be performing the function of bailout gas. It is therefore good practice to have the maximum bailout available to the diver in case a bailout situation and/or if the need for the buddy to perform a Controlled Buoyant Lift arises. In these cases a typical 2 or 3 litre, 232bar cylinder will be barely sufficient. Hence, BSAC recommends the use of an additional (off-board) bailout cylinder when diving deeper than 15m. In the case of mixed gas, the CCR diver may choose to use an independent off board source so that the mixed gas is not used for suit or BC inflation, since the poor thermal qualities of helium make it less suitable for suit inflation. The situation is more flexible in relation to the O2 cylinder since normally very little O2 is used during a dive. Occasionally, 232bar fills are not always available. However, since there is typically only a 2L or 3L oxygen cylinder, it is prudent to maximise the O2 available to the diver – in part
