>Hi Bill,
>
>> ----------
>> From: 	Bill Wolk[SMTP:BillWolk@ea*.ne*]
>> 
>> 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? 
>> 
>Heard it from a few different different divers and at least one dive shop
>technician.  Didn't dream it up myself. If you know different give me your
>experience.

OK -- between myself and my regular dive team with thousands of dives and 
even more partial pressure fills among us, we have neither seen nor heard 
of any "undetected oxygen flashes." If you think about it, neither has 
anyone you're citing to because "undetected" by definition means unseen.  
And -- since this "flash" happens inside a tank during a fill -- you 
should be skeptical about anyone who claims to have seen or heard one.  
So how have your sources detected the "undetected oxygen flashes?

>
>> It sounds like another gas handling "monster in the closet story" foisted 
>> on the diving public ... <snip>
>> 
>I assume from this statment that you don't know either....

No -- it means I'm reminding other divers who may believe this to be a 
significant problem (or worse, rush to buy the undetected oxygen flash 
detectors soon to be marketed by Dive Rite to go with their helium 
analyzer) that it isn't the first oxygen myth perpetrated by the dive 
industry. I've noticed that the whole oxygen cleaning mania has died down 
since the Navy reported that it had no problem testing a reg with buna 
o-rings gummed to the gills with silicone lube on a tank of pure O2.
>
>> 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."  
>> 
>That was the original intent of the post.... not sure you're adding anything
>constructive here nor that anyone needs your permission to provide input.
>Again give your experience if you have any

Done above -- but since there are many, many divers on this list with far 
more experience in fills, diving, and oxygen handling than I have, I 
asked everyone to add their own undetected oxygen flash reports to the 
thread to demonstrate the magnitude of the "problem" or lack thereof.  So 
far I have been underwhelmed by the response: none.  That should put the 
oxygen flash problem in perspective for you.

>> 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? 
>> 
>No. I'm talking about O2 cleaned cylinders PP filled and topped off with
>appropriately filtered air.

OK -- NONE.  There is nothing combustible in these cylinders. 
Furthermore, carbon monoxide is the by-product of incomplete hydrocarbon 
combustion -- i.e. combustion where there is insufficient oxygen.  In an 
high pressure 100% O2 environment -- like during a partial pressure fill 
-- any combustion of hydrocarbon contaminants -- as unlikely as this is 
to occur in the first place given your premises -- will be complete, 
producing CO2 and water.

Hmmm....maybe that's why the oxygen flash has been undetected.  It's 
beginning to look like the loch ness monster of scuba problems: I swear 
it exists. "Heard it from a few different different divers and at least 
one dive shop technician.  Didn't dream it up myself." I even have a few 
grainy photographs to prove it.

>
>>  If so, I have a few tips for you that are more important than the CO
>> detector:
>> 
>As the answer was no, the tips on dirty air are irrelevant.

No -- they're not. For divers concerned with contaminated gas and the 
entry of contaminants into their tanks that theoretically could ignite, 
they're by far the most important issues.  It's the simple, preventable 
foundation for fixing real problems.

>> The key to safe technical diving -- call it DIR or not -- is to identify 
>> *real* problems and to solve them as simply as possible. 
>> 
>Agreed
>
>> 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.
>> 
>Purely based on your post I'm still not sure that an undetected O2 flash is
>an 'Exaggerated problem rarely existing in the real world"  because you've
>provided no input to the contrary other than your assumptions.  Any real
>experience you have in this regard would be meaningful input. 
>
>It appears that all you're essentially saying is that CO contamination will
>not occur if you have clean tanks and air fills. That's not the real world..
>and that's not the attitude that PP filling is based on.

That is precisely the real world and exactly what I'm saying. If you have 
clean tanks and fills, where is the CO going to come from? Do you have 
first hand knowledge otherwise? Look at the DAN fatality reports and show 
me a single CO incident that did not involve a contaminated fill.  When 
you're debunking an exaggerated -- or mythical -- problem, showing the 
ABSENCE of any facts supporting "undetected oxygen flashes" is meaningful 
input. 
 

>I'm certainly no expert (hence the post to the Lists) but my understanding
>is that PP filling practices are based on the assumption that in this real
>world the cleaning of tanks and air may not remove all the combustible
>hydrocarbons.  Therefore we should PP fill the O2 very slowly just in case
>there are HC's present.  Now let's say that we mess up and PP fill our O2
>too fast and lets assume that we actually did have some HC's find their way
>into our 'clean' environment... we have combustion which produces CO...
>ordorless, tasteless, and toxic. 

And let's assume that pigs fly.  Here are the pertinent questions: 

How do we stop them all from getting away.  

Anyone out there have undetected flying pig traps? 

Can we clip their undetected invisible wings?

If this is the source of your concern and it will make you more 
comfortable, blast some pure O2 into your empty tanks to "burn" off the 
residual hydrocarbons, dump the now "contaminated" O2 and then fill them 
again more slowly. You've solved the problem until the next time your 
tanks are "contaminated."  And don't worry -- the oxygen flash will be 
undetectable.

>
>Hopefully now we're on the same page.  So here are the pertinent questions:

Clearly we're not and possibly not even on the same planet. What physical 
laws exist on your world?
>
>- Is this so rare that we needn't worry about it ?

Yes
>
>- Do we hear the combustion ?

At a fill station while you're filling?! Only if your Super Hearing works 
through steel tank walls
>
>- Is there an inexpensive, quick, and easy method to check for CO in the
>final fill ?  

Now if that alone had been your post without the dubious addition of 
"undetected oxygen flashes," we could have spent more time on substance 
rather than fiction. Carbon monoxide poisoning is both dose and time 
dependent.  A low does over a long exposure will kill you just as dead as 
a higher dose/short exposure.  Also, like any other gas, what matters in 
diving is the partial pressure of carbon monoxide.

Here is a toxicity table for CO concentrations at sea level pressure:

PPM CO        Time           Symptoms                                     
  
                                                                          
  

35 PPM        8 hours        Maximum exposure allowed by OSHA in the      
  
                             workplace over an eight hour period.         
  

200 PPM       2-3 hours      Mild headache, fatigue, nausea and 
dizziness.  

400 PPM       1-2 hours      Serious headache- other symptoms intensify.  
  
                             Life threatening after 3 hours.              
  

800 PPM       45 minutes     Dizziness, nausea and convulsions.           
  
                             Unconscious within 2 hours.  Death within 
2-3  
                             hours.                                       
  

1600 PPM      20 minutes     Headache, dizziness and nausea.  Death 
within  
                             1 hour.                                      
  

3200 PPM      5-10 minutes   Headache, dizziness and nausea.  Death 
within  
                             1 hour.                                      
  

6400 PPM      1-2 minutes    Headache, dizziness and nausea.  Death 
within  
                             25-30 minutes.                               
  

12,800 PPM    1-3 minutes    Death.


Draeger, among other companies, have in the last 3 years developed a new 
generation of more accurate CO sensors that work like the 02 sensors in 
oxygen analyzers -- producing more current or more resistance (depending 
on the sensor type) in the presence of elevated CO levels. The problem is 
that many of these sensors require elaborate calibration and others have 
a long response time and cannot provide the accurate, nearly 
instantaneous read needed to test scuba cylinders.  Do units exist that 
would do the job?  Yes -- Pioneer Air manufactures the Pionox inline high 
pressure breathing air analysis system.  Are they cheap? No.  Are they 
necessary, No. Is there such a thing as "undetected oxygen flashes" and 
will those flashes produce enough CO to warrant use of the Pionox system. 
No.  Should you have paid more critical reasoning time to this issue 
before perpetuating the CO contamination from "undetected oxygen flashes" 
myth.  Yes.

However, given this thread, I'm now sure Dive Rite will add a carbon 
monoxide monitor to go with their helium monitor. Remember what PT Barnum 
said...

>As intended in the original post and hopefully clarified here.... inputs
>from those with experience are appreciated.
>
>Best regards,
>Greg
>


Best regards --

Bill

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