An in-depth book on trimix diving?

[nadwidny]

A gas check with an Analox CO detector revealed 5-12ppm of CO in our trimix tanks once (car outside the filling station). The blender had believed that the filter... well... filters. Someone then asked if 5ppm really was a lot or not. I had no idea. I knew it was bad... but how bad? We chose not to dive. Now I want to be able to tell the effects of CO.

Your group is diving trimix and nobody knows what is bad or not? Amazing.

Finding 5ppm is bad. As I don't know the level of accuracy of the Analox (I'm going to assume around 1ppm otherwise to me it's pretty much useless) so are finding 4, 3, and 2 . If you've got CO in your tanks then the chances of having elevated levels of other contaminants like CO2 is very, very high.

 

[Agility]

Wikipedia says that 400ppm causes headache, and 800ppm causes convulsions.
A post above states that 140ppm is rapidly fatal.

Wikipedia is talking about 1atm while divers talk about much higher pressures.
the danger of CO like any gas lies in its partial pressure not its percentage.

The book I recommend is the Handbuch technisches Tauchen by Aspacher (AFAIK only available in German called the bible of technical diving)

 

[rjack321]

Finding 5ppm is bad. As I don't know the level of accuracy of the Analox (I'm going to assume around 1ppm otherwise to me it's pretty much useless) so are finding 4, 3, and 2 . If you've got CO in your tanks then the chances of having elevated levels of other contaminants like CO2 is very, very high.

The analox reports to 1ppm but its only calibrated to 100ppm. If I found >1 ppm on any diving quality CO meter I am dumping that tank too. God knows what else is in there and the accuracy and precision of something calibrated so far above standards is not reliable enough to trust my life.

I believe the UK and Canadian gas standards allow up to 5ppm CO (you tell me though?...), the US is a bit behind and allows 10ppm CO in air - which is widely considered outdated and too high for deep diving.

Any fill station with an intake anywhere near an automobile is not getting my business.