Continued Carbon Monoxide - Cozumel

[DandyDon]

Picked up 4 tanks from my LDS today. One tank had 1 ppm CO, the other three had none.

That's the way they should be and any fill station that tests much over that needs to check their compressors. Not all US compressors have inline monitors, even with our stricter rules and harsh court systems. I check every tank, everywhere tho, as it's good practice for trips out of country and - it's the only way to be sure. You can't be too picky about single digit readings from a portable tester as explained above, but you are in the safe range.

I had thought that liveaboards were not approved for the Anolox inline monitors (see Analox CO Clear: Analox - Looking after the air you breathe. ) but there was some misunderstanding on that and we now have one - the first!

Capt Wooki is a very impressive skipper with a tight boat and great safety record, whom I only got to dive with once before he moved to Florida to take trips to the Dry Tortugas - and I just got these messages, posted here with his permission...

Hooked up the CO clear to monitor room air, nitrox before it's compressed, nitrox after it's compressed, and compressed air today. The cleanest air is 4500 PSI scuba air at 0.3 PPM, then is High Pressure nitrox at 0.4 ppm, low pressure nitrox at 0.6 ppm, and room air at 1.2 ppm. Patti at Analox says we are the first liveaboard to invest in an Analox analyzer (installed).

Super! I thot you told me that the Coast Guard regs didn't allow that, or do I remember wrong?

It wasn't approved by the Coast Guard to test for hazardous atmospheres on tank vessels. I had to clear that with Patti before I purchased it.

So don't let any boat tell you that liveaboards can't install the monitors, as the M.V.Spree has one today.

 

[taucherguy]

DandyDon, just wanted to thank you here for making divers aware of the risks and problems with CO poisoning.
As I remember, CO just latches on to your hemoglobin and won't release easily. Meaning it will occupy the place that oxygen should occupy and not release like oxygen or nitrogen does. Since it won't release easily the small amount in the tank will compound in severity. This is as much I remember and hope that some professionals can shed more light here.

 

[swamp diver]

DandyDon, just wanted to thank you here for making divers aware of the risks and problems with CO poisoning.
As I remember, CO just latches on to your hemoglobin and won't release easily. Meaning it will occupy the place that oxygen should occupy and not release like oxygen or nitrogen does. Since it won't release easily the small amount in the tank will compound in severity. This is as much I remember and hope that some professionals can shed more light here.

There is a nice summary by Gavin Anthony, a well known British diving expert, in post #10 of this thread called "Carbon Monoxide in Diving".

 

[DandyDon]

I had two different Coz Ops send me test results from the main fill station after this thread started, in two different formats. I'll attach both, but I have come to think that they are worthless as the samples are possibly taken right after the filters are changed and when the compressors are first started, which is how I would do samples for public disclosure. Only an inline monitor really gives good info, and - I'm still going to check my tanks even if I see them filled then & there. The more I learn, the more I fear.

You'll notice that there were only 4 tests over 2 years at that...! :shocked2:

 

[taucherguy]

Thanks for posting and pointing it out. I must have missed it. Sounds like I still remembered some

There is a nice summary by Gavin Anthony, a well known British diving expert, in post #10 of this thread called "Carbon Monoxide in Diving".

 

[taucherguy]

I think what you have been doing is, even if it is not fully satisfactory to you, a step forward.
What do you think?

 

[DandyDon]

I think what you have been doing is, even if it is not fully satisfactory to you, a step forward.
What do you think?

Me? Yeah, I get frustrated at times, but not often. I'd still call these compressors on their substandard air even if I was the only one testing. I'm mean enough for that.

I'm not tho, and more are coming onboard with the testing & objecting. Knowing the Spree and the skipper, it was probably already the safest liveaboard out there, but it dam sure it now. Capt Wooki takes a lot of pride in safety.

 

[cruiser]

Dan--

It may seem like few people care about testing CO in tanks, but lurkers read this thread and their awareness is being raised (I know this for a fact). Some may even get a CO tester without posting about it. You're making progress that may not be readily apparent, but it's progress nonetheless.

 

[swamp diver]

I had two different Coz Ops send me test results from the main fill station after this thread started, in two different formats. I'll attach both, but I have come to think that they are worthless as the samples are possibly taken right after the filters are changed and when the compressors are first started, which is how I would do samples for public disclosure. Only an inline monitor really gives good info, and - I'm still going to check my tanks even if I see them filled then & there. The more I learn, the more I fear.

You'll notice that there were only 4 tests over 2 years at that...! :shocked2:

Don I think you highlighted one of the problems across the sport diving industry in that the frequency of air testing is woefully inadequate (it appears they only tested once in all of 2009) and typically the compressor operators sample under optimal conditions when the compressor is cold, and often only when the filters have just been changed out. Ideally they should be sampling only after the compressor has been brought up to full temperature at load and just before the filters are due to be changed. One can then be sure that the air quality meets the standard for the duration of the cartridge life.

Upon examining the LF results for the Cozumel central fill station one can say that they are generally not sampling immediately after the filter change as the carbon dioxide (CO2) values are close to ambient whereas typically immediately after a filter change they will be very low (i.e. < 100 ppm). The test #4 though was taken shortly after a filter change given the CO2 concentration at 218 ppm and ambient CO2 is approximately 380 ppm.

As you know if the air sample is taken only when the compressor is cold any lubricant oil dieseling due to overheating with subsequent CO production will not be picked up. I have attached portions of an article outlining this exact problem which occurred at the Montreal Fire Service in the 1990's. Fire fighters had been complaining of nausea and early fatigue while fighting fires despite being young and fit, and wearing their SCBA equipment. A researcher decided to check the SCBA bottles and found CO contamination at many fire halls (used a central compressor like on Coz) in the range of 1 to 250 ppm with the average being 60 ppm. :shocked2:

Upon further investigation they found that the " Bauer electric compressor" would only produce CO after it had been run at full load for 3 hours. This was determined by installing an inline CO monitor which showed the contamination as the compressor heated up to a point where the compressor oil auto-ignited or dieseled due to the excessive heat and poor ventilation.
Carbon monoxide and water vapor contamination of c... [J Toxicol Environ Health. 1997] - PubMed result

My guess is this is the same mechanism which explains what is happening at the central fill station in Cozumel, and until they install an inline CO monitor in order to verify that there is no CO produced throughout the entire compressor run cycle at full load those samples taken twice a year are meaningless and the risk of CO contamination still exists.

It may be even more complicated in that the only time their compressors will start dieseling the compressor oil is during the hot summer months and in the winter when the ambient temperature in the compressor room is cooler there is no CO produced.

Another factor is whether or not they are running a catalyst (Hopcalite) bed to convert any CO to less toxic CO2. The compressor say could produce CO contamination at the 3 hour mark but when the catalyst is dry it is able to remove the CO from the compressed breathing air. Towards the end of the cartridge life if the station is not monitoring their compressed air moisture levels the catalyst will become ineffective and allow the CO contamination into the breathing air. Catalyst requires extremely dry air in order to function effectively (i.e. dew point drier than -75 F).

Bottom line is that until this fill station installs inline CO monitors on its compressor system there is really no way to ensure that the contamination will not happen again. They could send a sample off to LF once a month and still not pick up the problem if it only occurs when the compressor is hot several hours into the duty cycle.

So you're right in that the individual diver should still carry some form of a personal CO protection device at all times.

 

[DandyDon]

Bottom line is that until this fill station installs inline CO monitors on its compressor system there is really no way to ensure that the contamination will not happen again. They could send a sample off to LF once a month and still not pick up the problem if it only occurs when the compressor is hot several hours into the duty cycle.

So you're right in that the individual diver should still carry some form of a personal CO protection device at all times.

Otherwise, you're diving on hope alone - which is what the Operators are simply accustomed to, on Coz, Roatan, Utilla, Belize, and so forth across the Caribbean basin, Bahamas, T&Cs, etc. And we still won't know how many post dive illnesses were caused by CO as the tanks still weren't tested - or how many drownings and diver errors were whitewashed stories? One version of the Roatan story is that the Honduran government did test the tanks finding dangerous levels of CO, but who knows what's true the way they hide things that are bad for business.

If the M.V.Spree can install one to serve 20 or so divers/100 or so tanks, would it not be reasonable to expect any serious fill station to do the same?! ​

I wonder if a big station like this one with more than one compressor could run all of their produce thru one Analox Clear monitor, or if they'd need one for each compressor? Not that it matters much, as we're still talking a few pennies/tank. My LDS in Lubbock doesn't run his compressor but once a week at times, but he has an Analox Clear monitor installed. Why don't the popular destinations care enough?

Because they never had to before...? ​

Any serious Nitrox diver has his own Nitrox analyzer and tests every Nitrox tank. Why is regular air not treated with the same seriousness? Hell, why do the dive Ops not have portable testers & 10 ppm calgas for testings?

Hey, DEMA is two months away. I wonder if there will be any new CO products there...???