Ronda Cross Tank CO Test cause of Death

[swamp diver]

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.

Read post #102 above.

The fire halls through the standard NFPA 1989 must submit quarterly samples to an accredited breathing air laboratory such as Lawrence Factor, TRI, Trace Analytics, etc. Those same labs are the ones prior to PADI's policy change in 2009 where dive shops also sent their quarterly samples for compressed breathing air analysis.

The lab directors can access aggregate data by industry and by contaminant in order to look at these issues. Read the Dive Alert article in the post above by Bob Rossi and you will see the lab directors from LF and TRI quoted. In 2009 those CO failure rates remained at 3% for the dive industry (personal communication).

As for the mechanics of sampling it is not the tanks which are normally analyzed but a sample is taken directly off the compressor hopefully while it is hot and has a filter in that is just due to be changed out. Sampling just prior to the filter change ensures that the air quality is maintained through the service life of the filter.

You can watch a Youtube video on TRI's web site showing how their sampler works. One can sample off a tank if the air is suspect but generally all quarterly samples are taken from the compressor directly. Of course quarterly sampling is not without problems which is why inline CO monitors are now mandatory on all US and Canadian fire hall compressors and Canadian commerical dive operator compressors. They should be mandatory on all recreational dive compressors.
Scuba Grade E Air

 

[Wookie]

I no longer trust the labs. I failed for CO in September. Now, I have a CO monitor on my compressors, which I keep calibrated IAW Analox's procedures. I've never seen it go above 0 except on startup. Anyway, I failed for well over 100 PPM CO. I retested the exact same bank air on the retest. Passed with flying colors. There is some weird QA at the labs.

 

[swamp diver]

I no longer trust the labs. I failed for CO in September. Now, I have a CO monitor on my compressors, which I keep calibrated IAW Analox's procedures. I've never seen it go above 0 except on startup. Anyway, I failed for well over 100 PPM CO. I retested the exact same bank air on the retest. Passed with flying colors. There is some weird QA at the labs.

Labs do make mistakes from time to time, but it is very rare IF you are using an accredited laboratory. Accreditation by the AIHA or A2LA means that the lab premises and equipment are inspected, its QA policies and procedures are verified, staff training and credentialing is verified, but most importantly an accredited lab must partake in a quarterly proficiency testing program run by the University of Washington. This is a program where the lab is sent a blind sample with CO, CO2, ethane, and volatile hydrocarbons contamination plus an oxygen concentration between 15% and 30% which they must analyze and send the results back to the university in order to compare with the actual results. This program keeps the labs honest and hopefully minimizes the risk of what you experienced. I suspect what happened is there was a sample ID problem.
http://airtesting.com/wp-content/uploads/2013/05/CAPT-Protocol_R6a.pdf

You should be still testing your compressed air on a regular basis because your CO monitor tells you nothing about total volatile hydrocarbon, CO2, or oil contamination although you could purchase an inline monitor for this, but the technology is still not there in my opinion. Analox has a monitor now for oxygen, moisture, CO, CO2, and volatile hydrocarbons but keeping it all calibrated can be a challenge. The US Navy despite trying to develop an all in one monitor for its base and shipboard compressors still sends all 3000 yearly samples to TRI in Texas who run an excellent lab. I'd give them a try.

And don't just blindly trust the CO monitor calibration gas concentration at face value. We had a bottle of 20 ppm calgas which I ran into one of the calibrated Analox compressor monitors and noticed it said only 14 ppm. We sent it over to our local accredited compressed air lab and had them analyze the calibration gas. It was supposed to be 20 ppm and analyzed out at 13.8 ppm. Upon reviewing the incident we determined that the calibration gas company we were using was not accredited but they had much cheaper calgas. We now use Air Liquide's Scotty gas or Calgaz and have never had a problem again but pay 50% more for that ISO 17025 accreditation they carry. GasCO out of Florida is not accredited for calibration gas.

 

[Wookie]

Labs do make mistakes from time to time, but it is very rare IF you are using an accredited laboratory. Accreditation by the AIHA or A2LA means that the lab premises and equipment are inspected, its QA policies and procedures are verified, staff training and credentialing is verified, but most importantly an accredited lab must partake in a quarterly proficiency testing program run by the University of Washington. This is a program where the lab is sent a blind sample with CO, CO2, ethane, and volatile hydrocarbons contamination plus an oxygen concentration between 15% and 30% which they must analyze and send the results back to the university in order to compare with the actual results. This program keeps the labs honest and hopefully minimizes the risk of what you experienced. I suspect what happened is there was a sample ID problem.
http://airtesting.com/wp-content/uploads/2013/05/CAPT-Protocol_R6a.pdf

You should be still testing your compressed air on a regular basis because your CO monitor tells you nothing about total volatile hydrocarbon, CO2, or oil contamination although you could purchase an inline monitor for this, but the technology is still not there in my opinion. Analox has a monitor now for oxygen, moisture, CO, CO2, and volatile hydrocarbons but keeping it all calibrated can be a challenge. The US Navy despite trying to develop an all in one monitor for its base and shipboard compressors still sends all 3000 yearly samples to TRI in Texas who run an excellent lab. I'd give them a try.

And don't just blindly trust the CO monitor calibration gas concentration at face value. We had a bottle of 20 ppm calgas which I ran into one of the calibrated Analox compressor monitors and noticed it said only 14 ppm. We sent it over to our local accredited compressed air lab and had them analyze the calibration gas. It was supposed to be 20 ppm and analyzed out at 13.8 ppm. Upon reviewing the incident we determined that the calibration gas company we were using was not accredited but they had much cheaper calgas. We now use Air Liquide's Scotty gas or Calgaz and have never had a problem again but pay 50% more for that ISO 17025 accreditation they carry. GasCO out of Florida is not accredited for calibration gas.

Actually, I get my cal gas from Analox. I use one of the 3 big airtest labs, they've been around forever, but I guess I should check their creds a little closer. It's always nitrox, BTW, never air that fails.

I will be marketing an inline real time gas monitor adapted from the refinery industry. I have a friend who used to work for Honeywell, then went out on her own making a laser (light diffusion) monitor for stack gas emissions. It works fine for sample air flow except for managing the laser at 6,000 PSI. In monitoring stack gas, the exhaust is at ambient. If you want to monitor real time compressed air flow, you need to build a window that won't allow anything to settle on it, thereby messing up the refraction, or build a laser good for 6,000 PSI and house it. None are showstoppers, but she has other things on her mind right now.

I never thought about marketing it to the navy, maybe it should come off the back burner...

 

[swamp diver]

Actually, I get my cal gas from Analox. I use one of the 3 big airtest labs, they've been around forever, but I guess I should check their creds a little closer. It's always nitrox, BTW, never air that fails.

I will be marketing an inline real time gas monitor adapted from the refinery industry. I have a friend who used to work for Honeywell, then went out on her own making a laser (light diffusion) monitor for stack gas emissions. It works fine for sample air flow except for managing the laser at 6,000 PSI. In monitoring stack gas, the exhaust is at ambient. If you want to monitor real time compressed air flow, you need to build a window that won't allow anything to settle on it, thereby messing up the refraction, or build a laser good for 6,000 PSI and house it. None are showstoppers, but she has other things on her mind right now.

I never thought about marketing it to the navy, maybe it should come off the back burner...

I would not be surprised if Analox is purchasing their calibration gas from Gasco out of Florida or MSA, neither of which hold an ISO accrediation. GasCO bottles are beige with green lettering.


Do your homework on those all in one monitors as they are fraught with problems in particular when trying to maintain accuracy and precision for the volatile hydrocarbons.

The US Navy tried an FID for VOCs but having to have hydrogen on board was not ideal so they switched to a PID. The PIDs perform very poorly in high humidity environments (all dive environments) and the bulbs are very expensive and finicky to keep in calibration. The unit the US Navy tested from Geotech is in the photo below and if you go onto Rubicon Repository the Navy's report on testing of the unit is available there. The Navy felt it would suffice but a real problem with all these units is the training required to keep the units functioning. The Navy felt that with their rotation schedules they would be forever training a new person on these units because the units are labor intensive. Also they would still have to use a lab for the oil and moisture specification in their breathing air standard.

That being said Geotech has now commercialized the unit and has it for sale here. It won't do moisture which is important for those of us diving in cold water or with breathing air standards (Canada, Europe, and Australia) which have a moisture specification.
DiveAir 2 for CO2 and O2 measurement in compressed air

The Analox unit came out two years ago and is more advanced than the Geotech unit, but having used a PID for VOCs in the field I can say it would require very frequent calibration and bulb cleaning. You'll find it is a lot cheaper to send in a quarterly sample than to purchase and maintain one of these units plus the oil testing procedure on the Analox unit is not reliable.
ACG: Analox - Looking after the air you breathe.

 

[swamp diver]

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.

Can you tell us where you purchased one for that great price? Usually they run about $340 per unit.

I have had the Analox EII CO analyzer for 4 years now and it is a very reliable unit, but make sure you download the manual from Analox (not included with the unit) and read it for all the do's and don'ts of use.
http://www.analox.net/proddetail.php?productid=91&ref=2

Recently I acquired a Sensorcon unit which is $179 and not quite as easy to use as the Analox unit but they appear well built. Best of all the sensor replacement is cheap and one can send the unit back to the US company to get calibrated for a reasonable fee. It will take some time to see how these units actually hold up in the field given that high heat, humidity, and cross-reacting volatiles (i.e NO) can be a challenge for CO analyzers.
Cabon Monoxide Scuba Tank Analyzer

 

[Shasta_man]

My wife got serious carbon monoxide poisoning in Taveuni with Swiss Fiji Divers just from the ride on the dive boat out to the dive site. It happened twice. She went from being fine to spitting and lying directly on the beach for 15 minutes to recover.

It was a large metal ocean speedboat which had the tanks down the sides, with a windshield and a top from the windshield to the back of the boat. The boat used twin 200 HP outboard motors. The roof made a low pressure area just in front of the engines so the exhaust just rolled up into the passenger area. With tanks down the side, she wasn't tall enough to get her head out to fresh air, while I could. I didn't realize it was all carbon monoxide until the second trip. The dive guides knew this was a problem and also stood at the back of the boat exposed to the wind to escape the problem.

 

[swamp diver]

My wife got serious carbon monoxide poisoning in Taveuni with Swiss Fiji Divers just from the ride on the dive boat out to the dive site. It happened twice. She went from being fine to spitting and lying directly on the beach for 15 minutes to recover.

It was a large metal ocean speedboat which had the tanks down the sides, with a windshield and a top from the windshield to the back of the boat. The boat used twin 200 HP outboard motors. The roof made a low pressure area just in front of the engines so the exhaust just rolled up into the passenger area. With tanks down the side, she wasn't tall enough to get her head out to fresh air, while I could. I didn't realize it was all carbon monoxide until the second trip. The dive guides knew this was a problem and also stood at the back of the boat exposed to the wind to escape the problem.

This is a much more common problem that the dive industry acknowledges and not hanging out at the back of the boat where exhaust levels are high also should be included in the basic open water training materials.

There was a case on one of the technical dive boards about 8 years ago where a diver on the way to the dive site was found unconscious at the back of the boat, and on Rebreatherworld there is a CO incident from breathing boat exhaust on the back of the charter boat. CO poisoning will be worse on a RB than on open circuit because as you force the CO off the hemoglobin molecule with hyperbaric O2 at depth the toxic gas re-enters the breathing loop only to be breathed again. On open circuit any CO from boat exhaust attached to your hemoglobin which is displaced at depth by O2 leaves the circulation for good on exhalation assuming you make it to depth and don't drown first.

I've measured CO at the back transom on a dive charter as high as 500 ppm so if you preload your blood on the way out to the dive site with 500 ppm you'll likely be unconscious by about 40 feet and be written up as a heart attack unless a carboxyhemoglobin blood level (COHb) is done post-mortem. In this case the blood COHb will reveal the cause of death, CO asphyxiation from boat exhaust, but the tank CO will be negative.

So how common is this problem? Huge, in a 20 year period from 1990 to 2009 in the US there were over 880 boat CO poisonings documented with 160 fatalities. The worst boat designs are the houseboats due to the large 'station wagon effect' and the cabin cruisers with inboard gas engines.

With a portable CO monitor one can monitor the safest place to sit on the dive boat. On my last dive trip south the entire cabin had a CO level of 75 ppm and only up on the bow in front of the windscreen could one escape the exhaust.

Source for above data:
Boat-Related Carbon Monoxide Poisoning

---------- Post added December 25th, 2013 at 04:55 PM ----------

In the past to measure COHb one had to draw blood and have non-expired expensive reagents on hand to run the test in a laboratory. This took time and money. As a result most small hospitals did not offer the test which would include the one on the island of Cozumel.

Now one can use pulse oximetry to measure COHb which is a non-invasive test I (see slide #36 above). I've always felt that the chamber at every major dive area should have one of these units to screen divers for CO poisoning whether from boat exhaust or compressed air contamination. It would be nice if DAN would possibly look at supplying their member chambers in major dive centres like Cozumel, the Red Sea, Thailand, etc. with donated COHb pulse oximeters. Cost is about $3700 per unit.

This would certainly help identify these CO poisoning incidents in order that they were treated as such rather than writing them up as a drowning or myocardial infarction as has been typically done to date.

Masimo - Rainbow SET Pulse Oximeters - Rad-57
Accuracy of carboxyhemoglobin detection by puls... [Anesth Analg. 2013] - PubMed - NCBI

 

[John C. Ratliff]

I have finally read this thread, and went through the whole thing tonight. Let me say that I am a Certified Industrial Hygienist, and am very familiar with sampling techniques.

The video clip from You Tube shows the test, but the procedure is invalid--it does not zero the unit and contain a "bump test" of the instrument. A bump test is required for this instrument's results to be used to determine anything legally. Without it, and without the calibration data on the instrument, the test results cannot be used to make determinations that are legally binding. I have read the Analox EII CO tester's manual, and the manufacturer states that the instrument should be calibrated every six months, and bump tested every use. There are two types of bump tests recommended by the manufacturer, one being the "traditional method" with a calibration gas, and the other being a test with your breath. Unless a person is a smoker, there should be no CO (carbon monoxide) in a person's breath, unless there is CO in air pollution the person is breathing. Our breath has CO2 (carbon dioxide). Therefore the Analox EII apparently reacts to carbon dioxide too. This can compound any reading. I note also that the test gas is at 10 ppm CO, but the manufacturer states that the acceptable range is 7 ppm to 13 ppm; this is a 30% factor each way, which indicates that this is not an especially sensitive instrument to use (I'm used to 0.5 ppm off, and if it is being able to bring the unit back into calibration). But without a bump test, the unit's calibration and sensitivity are in question.

Normally, in testing air samples, the NIOSH measurement methods are used. For CO this is #6604.
CDC - NIOSH Pocket Guide to Chemical Hazards - Carbon monoxide
http://www.cdc.gov/niosh/docs/2003-154/pdfs/6604.pdf

Normally, for legal reasons I only use an American Industrial Hygiene Association's Accredited Laboratory for testing these kinds of samples.
default

I thought that it is important for CO measurement to do it correctly, both for legal reasons and for the personal sampling that divers are doing.

John (SeaRat)

John C. Ratliff, CSP, CIH, MSPH

 

[DandyDon]

Hi John,

I agree, as I did at the first, that the video does not clearly prove anything.

For a non-smoker to blow on an Analox sensor as a bump test, I am sure the results should be lower than for a smoker blowing - but it was my understanding that even non-smokers exhale some CO naturally. Anytime there is the union of Carbon and Oxygen, there will be some amount of CO produced - the goal being to keep that as low as possible, but even in a non-smoker's body, some will be produced.

Nonetheless, as a safety defense, once an Analox unit is bump tested and field calibrated, it should serve well in avoiding dangerous tank fills. Measuring in parts per million in the lower range has to be technically challenging, 10 ppm being equal to 0.001%. I feel confident that we are much safer using that unit or similar than the old approach of nothing.