On 8/30/01 Porter, Greg, Gregory.Porter@AR*.Bo*.co* wrote

>Given the possibility of having an undetected Oxygen flash while PP filling,
>and given that the resultant Carbon Monoxide in the cylinder would be
>tasteless, odorless, and lethal, is anyone testing fills with a CO detector

[snip]

Greg -

Before we get to the carbon monoxide detector, where did you come up with 
the idea that there's such a thing as an "undetected Oxygen flash" in the 
first place? 

It sounds like another gas handling "monster in the closet story" foisted 
on the diving public by the same people who brought you expensive oxygen 
cleaning of already clean tanks and regulators:  "Don't partial pressure 
fill or the undetected oxygen flash might get you."

Would everyone out there who has experienced a "detected Oxygen flash" 
please write Greg so he understands the magnitude of the problem he's 
trying to "fix."  

Let's start at the beginning: oxygen is an oxidizer. It is not itself 
combustible. For there to be an "oxygen flash," your tank already has to 
be contaminated with something combustible  and that fuel has to ignite. 
Have you ever found oil in your tanks when they've been VIP'ed?  If so, I 
have a few tips for you that are more important than the CO detector:

Tip No. 1 -- get your tanks filled at reputable fill stations, i.e. those 
with several working filters on their compressors; 

Tip No. 2 -- if your last air fill tastes like compressor oil, VIP and 
clean the tank before you partial pressure fill. 

Carbon monoxide contamination in scuba breathing gas is most frequently 
introduced by fill stations with their intake ports close to busy 
streets, crowded parking lots or even the exhaust of their own 
gas-powered compressors. In other words, the CO is a by-product of 
internal combustion engines not oxygen flashes. If you're getting your 
fills at one of these places, save your money on the CO detector and just 
go elsewhere.

The key to safe technical diving -- call it DIR or not -- is to identify 
*real* problems and to solve them as simply as possible. Exaggerating 
problems that rarely exist in the real world and then coming up with 
convoluted solutions to solve these non-existent problems makes diving 
more dangerous, not less.

Best regards --

Bill

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