Rebreather

Question
QUESTION: Are re-breathers safe?

ANSWER: Hi John,
First, let me apologize for the delay in answering your question.  I changed my email address and that change didn't get to the AllExperts site.  As a result, I haven't been receiving notice of questions.

Rebreathers are safe as long as proper use and training are exercised.  They are very complex systems and, with complexity comes the increased chance that things can malfunction.  They are computer controlled systems and there are back-up computers as well as manual emergency "bail-out" equipment carried by the diver in the event that it is needed.

Most rebreather manufacturers require a rigorous training program for a user before the equipment is released to him even after he purchases it.

With proper training and use, rebreathers open up areas and depths that are unavailable to recreational open-circuit divers.  Open circuit is the type of diving most divers are familiar with...exhausted air exits the regulator as a stream of bubbles.  Rebreathers do not exhaust the entire breath, it is recycled or "rebreathed".

John, I hope this answers your question and, once again, I apologize for the delay in responding.

Mike

---------- FOLLOW-UP ----------

QUESTION: Hi Mike,
Are there any statistics on rebreathers and who regulates them?  Breathing air out of a tank is a simple solution to diving.  Removing CO2 seems complex and prone to error.

Answer
Hi again, John

Sorry for the delay in answering your question but I left a message for an experienced rebreather diver and have not heard back from him regarding any regulatory requirements.

To my knowledge, there are no official regulatory requirements other than those imposed by the rebreather manufacturers themselves.  I covered that in an earlier question from you.

I'm not sure what statistics you are looking for.  Safety?, Accident Rate?, Increase in the use of Rebreathers over Open Circuit?  Not sure what you're asking for on that one.  I don't have any reliable information on any of those.

The principals involved in rebreathing really aren't that complicated.  The carbon dioxide is removed from the exhaled air through the use of a granular scrubber material contained in a canister and the air is passed through it.  This scrubber material is simply replaced after a series of dives.  Oxygen is also replaced as it is used though the use of a small tank of pure oxygen attached to the diving unit.  An oxygen sensor measures the amount of oxygen in the air and replenishes it as needed through a valve in the air loop.  A computer controls the entire process.  There are usually redundant computers involved so there is a backup if one fails.  So, while the process is fairly simple and straight forward, the computer control is sophisticated.

Hope this helps.

Mike