For each exhalation, the breathing circuit is emptied of gas corresponding to the amount of fresh gas that is dispensed into it.

The amount of bubbles that is discharged from the breathing circuit is inversely proportional to the depth, i.e. less at greater depths. This is due to the amount of gas dispensed into the circuit remaining constant regardless of the depth. The gas bubble that is emptied into the water becomes less and less the higher the pressure becomes (deeper as the diver descends).

The amount of bubbles also depends on the dose chosen on the dosage selector; the higher the dosage ratio (GREEN) the greater the amount of gas dispensed.

Example

Diving towards an acoustically sensitive object that is shallower than 30 m on GREEN gas i.e. a high dosage, is considered to be a sub-optimal dive.

Tip: In order to minimise the acoustic signature of the exhalation bubbles, the diver can:

Breathe calmly and evenly, spikes in breathing will give spikes in the quantity of bubbles from the diffuser, which in turn gives a worse acoustic signature.

The diver is to shield the bubbles by trying to have as much of his body and the IS-MIX between himself and the acoustically sensitive object, i.e. lie with the body at a low angle to the object and lie at right angles to the sensitive objects.

Make sure the bubbles are carried away by the current, i.e. approach the acoustically sensitive object against the current.

Swim towards the sensitive objects at the same (constant) depth.

Remark

Tip: To avoid underpressure in the diffuser and the consequent risk of flooding, all descents must be slow, which is particularly important near the surface where the pressure gradient is the greatest. Perform a by-pass near the surface to ensure that the diffuser is filled with gas.