In Danish |
Rebreathers in general
A rebreather
is circulation system for your breathing gas, in theory a rather simple
system that allows you to use the part of the oxygen that is left in the
respiratory gas mix, after you have exhaled it from your lungs. In simple
terms the exhaled air will take a trip around the loop of the rebreather and
is used again. Before you breathe the gas mix again, it will travel through
a filter that cleans out the carbon dioxide.
Then there is the question of oxygen? Every time the gas mix passes your
lungs a small part of the oxygen is metabolised by your body. A normal
person will metabolise approximately 1 litre oxygen per minute. It’s crucial
that the system is replenished with fresh oxygen in just the right amount.
Both too little and to much can be fatal.
The mechanism to compensate for the use of oxygen marks the most important
difference between semi-closed and fully closed rebreathers. The semi-closed
units will inject some sort of nitrox into the loop at a constant pace, and
to keep the volume constant it will compensate by releasing some bubbles.
However, most fully
closed rebreathers will measure the actual amount of oxygen in the loop, and
replenish just the right amount in accordance with the metabolism. This is
why there are no bubbles from a fully closed system. |
