Okay, I’m not a technical diver, nor do I dive a rebreather. I’m an old-style antiquated vintage diver using open circuit (I collect and dive old regulators too). But reading this, I thought I’d go to Google Scholar and see if there was anything I could find, and I did find something you might be interested in.
Workshop on Enriched Air Nitrox Diving
books.google.com
As a retired industrial hygienist, I would like to suggest that limits for CNS are applied so as to protect the greatest number of divers possible without incurring an incident. While violating these limits can be done, you may not understand the underlying physiological reasoning behind the limits presented.
In the occupational health realm, we have the OSHA limits, or Permissible Exposure Limits to chemical hazards. Because these must be put in place in a public forum with hearings, they are now rarely updated because of the type of process they must go through. But another organization, the American Conference of Governmental Industrial Hygienists, update their Threshold Limit Values regularly, based upon the latest scientific knowledge. The ACGIH TLVs are usually much lower than OSHA’s PELs.
I’d suggest that the problems you are having with the CNS recommendations may be in the same vein, and be the best recommendations for keeping the greatest number of divers from having CNS effects, regardless of the experiences of some who’s “bent” or “broken” these recommendations over and over again.
For instance, on pages 46 and 47 of this above publication, they talk about the high percentage of oxygen in the mix leading to a decrease in the lung’s vital capacity. This is not something that you as a diver will perceive without testing for it. So there are potentially other effects than a CNS “hit” with convulsions that come into some of these recommendations.
SeaRat
