Ronda Cross Tank CO Test cause of Death

[DandyDon]

If that were true we would be hearing about way more incidents than we do.

I didn't say dead. Well, many dive destinations lack ability to test tanks for CO or bodies for carboxyhemoglobin (COHb) so the mortality rate could be higher than we realize - and I have a hunch that it is. No tank should have any CO, because where there is some, there could be a lot at times.

Otherwise, I'll defer to the next post following as better said than what I could...

 

[swamp diver]

Some studies show 3% of tanks are CO tainted, and my experiences have been higher.

One doesn't need studies just go to the horses' mouths which are the guys who run the accredited compressed breathing air labs in the USA. These labs analyze samples not only from US and Canadian dive compressors but from dive centers all over the globe particularly those in the tropics where the risk of CO production is higher due to high ambient heat.

In 1998 both Lawrence Factor in Florida and TRI in Texas (they are the lab which does 3000 samples a year for the US Navy compressors) reported in Alert Diver that 5% to 8% of "dive" samples failed for carbon monoxide (CO) at the 10 ppm level. That number is huge and highlighted the extent of the problem in the industry.

In 2004 Bob Rossier who wrote the original Alert Diver article asked these same two labs again about the frequency of compressed air failures for carbon monoxide in the dive industry. Sadly it was still far too high at 3% to 5% at the 10 ppm threshold. I have spoken to one of those lab directors in 2009 and he said rate of failure still remains at 3%.

View attachment Carbon Monoxide DAN Alert Diver 06-04.pdf

Now that corporate PADI has got out of the business of overseeing its dive centers and resorts for compressed air quality and instead allows the local jurisdiction to regulate compressed air quality I suspect the rates of failure to worsen. There is little to no local oversight of compressed air quality in locales such as Mexico and other tropical dive destinations. Even in the US there is evidence that since the PADI change in policy on this matter US dive centers have stopped testing their air or reduced it from quarterly to once a year.

View attachment EPA Diver's Lament.pdf

The diver once outside of Canada, USA, Europe, or Australia is pretty much on his/her own with respect to the most important aspect of the dive, one's air/gas quality. For that reason I would not set foot in the tropics these days without a handheld CO monitor to test each and every tank before use.

 

[swamp diver]

If that were true we would be hearing about way more incidents than we do.

Dr. Caruso the US air force pathologist reviewed close to 500 diving deaths for DAN over a 15 year period (if I recall) and found interestingly that in the fatalities where either the tank air or blood was analyzed for CO post mortem that in about 3 percent of the cases CO was detected. In the tanks no CO should be detected. COHb will be elevated in a smoker's blood post mortem.

As Don pointed out it is still rare to analyze a diver's blood for carboxyhemoglobin especially in the tropics. If one doesn't do these tests routinely in all dive fatalities the true incidence of the CO problem will remain under-reported.

Just so you don't think this is a problem confined solely to the tropics have a look at this study from Texas where 27 anonymous samples were taken from local dive shops. One tank contained 25 ppm of CO and the nitrox results give one pause for thought.
[abstract] RECREATIONAL SCUBA AIR AND EAN NITROX QUALITY




---------- Post added December 21st, 2013 at 10:09 PM ----------

Depends on how bad they need to be in order to be considered "tainted". Also it would not surprise me if the percentage of "tainted" tanks are way higher in some locations than in others...

Yes and tainted tanks are far more common in some industries such as the dive industry when compared with compressed air samples from the fire service.

The CO failure rate at 10 ppm in the dive industry remains about 3% whereas in the US fire service the CO failure rate is ~0.1%. Same oil lubricated compressors but vastly different rates.

In the fire service the compressor operators are properly trained, air samples are taken quarterly, CO monitors are mandatory, and most importantly the equipment is installed and maintained as per manufacturer's recommendations.

 

[Tigerman]

Dr. Caruso the US air force pathologist reviewed close to 500 diving deaths for DAN over a 15 year period (if I recall) and found interestingly that in the fatalities where either the tank air or blood was analyzed for CO post mortem that in about 3 percent of the cases CO was detected. In the tanks no CO should be detected. COHb will be elevated in a smoker's blood post mortem.

As Don pointed out it is still rare to analyze a diver's blood for carboxyhemoglobin especially in the tropics. If one doesn't do these tests routinely in all dive fatalities the true incidence of the CO problem will remain under-reported.

Just so you don't think this is a problem confined solely to the tropics have a look at this study from Texas where 27 anonymous samples were taken from local dive shops. One tank contained 25 ppm of CO and the nitrox results give one pause for thought.
[abstract] RECREATIONAL SCUBA AIR AND EAN NITROX QUALITY




---------- Post added December 21st, 2013 at 10:09 PM ----------



Yes and tainted tanks are far more common in some industries such as the dive industry when compared with compressed air samples from the fire service.

The CO failure rate at 10 ppm in the dive industry remains about 3% whereas in the US fire service the CO failure rate is ~0.1%. Same oil lubricated compressors but vastly different rates.

In the fire service the compressor operators are properly trained, air samples are taken quarterly, CO monitors are mandatory, and most importantly the equipment is installed and maintained as per manufacturer's recommendations.

And yet, the numbers could be the opposite here in Norway than they are in the US and Canada (I wouldnt know as I dont have stats for it)...
Incidentally most of my air comes from firestations and powerplants (who use the air for their inhouse firefighters and also for reservoiar depth measurements)

 

[NAM001]

Well i have procrastinated enough in regards to CO testing. I just bought a analox. 290 with shipping. This thread has been an wake up call for me.

 

[Peter_C]

If that were true we would be hearing about way more incidents than we do.

Well I have first hand experience as do 16 other people I was diving with. To me that is a pretty large number. Was there a death, no, but it was a near miss with many people, and a couple came up puking, with most others having bad headaches. It caused me to buy a CO meter.

 

[fisheater]

Well I have first hand experience as do 16 other people I was diving with. To me that is a pretty large number. Was there a death, no, but it was a near miss with many people, and a couple came up puking, with most others having bad headaches. It caused me to buy a CO meter.

And it was a very credible and up-to-then reliable U.S. source that happened to have an unexplained compressor problem, which didn't appear to be the result of incompetence or negligence.

The "takeaway" is that it could happen to anyone and relying on reputation won't prevent it from happening to you.


Sent from my iPhone using Tapatalk

 

[clownfishsydney]

Yes and tainted tanks are far more common in some industries such as the dive industry when compared with compressed air samples from the fire service.

The CO failure rate at 10 ppm in the dive industry remains about 3% whereas in the US fire service the CO failure rate is ~0.1%. Same oil lubricated compressors but vastly different rates.

In the fire service the compressor operators are properly trained, air samples are taken quarterly, CO monitors are mandatory, and most importantly the equipment is installed and maintained as per manufacturer's recommendations.

Possibly the answer for this apparent anomaly is that dive shops fill tens of thousands of cylinders a year where a fire station (or even a group of stations) would fill maybe in the hundreds a year. This is going to mean that the fire service compressor is much newer and in better condition than a dive shop.

 

[swamp diver]

Possibly the answer for this apparent anomaly is that dive shops fill tens of thousands of cylinders a year where a fire station (or even a group of stations) would fill maybe in the hundreds a year. This is going to mean that the fire service compressor is much newer and in better condition than a dive shop.

Try visiting a few hundred dive shop compressors and you'll see the problems. Bad installs with little ventilation, narrow intakes, poor maintenance, running mineral oil, no catalyst, no CO monitors, untrained operators, etc.

Most dive shops do not fill tens of thousands of tanks a year except in the large tourist areas of Florida, Mexico,Australia etc. yet we still get those high CO failure rates.

Over here the large urban fire services have consolidated their number of fill stations in order to improve air quality. In Ottawa a city of a million people they used to have 14 fill stations throughout the city. Now they have 4 fill stations, each one is much larger and fills for the other stations, but with only 4 compressors to maintain and train operators it is much easier to monitor production quality. Those 4 fill stations pump a lot more air than the average dive shop and typically up to 6000 psi.

You are correct in that fire service compressors given they are funded by municipal taxes are typically in much better condition than the 25 year old compressor jalopies we see in the dive industry.

 

[boulderjohn]

Yes and tainted tanks are far more common in some industries such as the dive industry when compared with compressed air samples from the fire service.

The CO failure rate at 10 ppm in the dive industry remains about 3% whereas in the US fire service the CO failure rate is ~0.1%. Same oil lubricated compressors but vastly different rates.

Serious question: where do these numbers come from? I am not familiar with the process by which tanks in scuba shops and fire houses are checked for CO contamination, and I would appreciate the explanation.