Carbon Monoxide - essential knowledge for ALL divers

[Doc Harry]

Do rec divers not know about CO?

The issue of CO has been discussed in great detail in many other long and detailed threads

Likewise there are many, many threads about the different CO analyzers

 

[Aotus]

I found that most divers even technical divers don't know about CO! Some know something about it, but most don't know all of it. Even gas blenders have some idea but for instance did not know that partial pressure blending could be one source of CO getting missed unless you check the tank afterwards rather than just relying on your CO sensor on the station.

When Mike Young from KISS rebreathers related a story about him experiencing first hand a CO poisoning event, I realized how little I knew about it. Since then, I put together a lecture we present at ADDHelium. The next time we stream this life, I will post it here for those interested.

Claudia Roussos MD

this far exceeds my knowledge as well. I'd love to see that show.

---------- Post added April 19th, 2015 at 12:25 PM ----------

The issue of CO has been discussed in great detail in many other long and detailed threads

Likewise there are many, many threads about the different CO analyzers

uh huh...well, like I said,

...I decided to write this post initially to report my own experience to fellow cave divers on the CDF. But, thinking back about the dive shops I called that were not aware that portable CO analyzers were used for scuba, it got me thinking that another plug for ALL divers to test there gas is never a bad thing. It's clear from many posts on these forums that a lot of rec divers in particular don't test their gas because they trust their shop, because CO poisoning doesn't happen often, or because they just don't know about it...

and sure enough,

I just finished my PADI O/W course and I haven't heard the word Carbon Monoxide/CO even mentioned (in relation to scuba) until now. Thanks for the post

 

[grf88]

The issue of CO has been discussed in great detail in many other long and detailed threads

Likewise there are many, many threads about the different CO analyzers

Despite its many members Scubaboard only reaches a small fraction of scuba divers. Until the last few years there has not been that much discussion even here about CO. I think we should thank Dandy Don for being very vocal on the subject and causing more of us to think seriously about it and take steps to protect ourselves.

 

[SteveInMD]

Good info here. Thank you.

How sensitive are the CO meters to storage? Do they easily go out of calibration? I'm not lucky enough to be a frequent diver. A few times a year is all I can do. I'm wondering if buying a meter would still be smart or would it be unreliable after a few uses and long storage periods.

 

[Aotus]

Good info here. Thank you.

How sensitive are the CO meters to storage? Do they easily go out of calibration? I'm not lucky enough to be a frequent diver. A few times a year is all I can do. I'm wondering if buying a meter would still be smart or would it be unreliable after a few uses and long storage periods.

It depends on the sensor, but I'm afraid i don't have the expertise to answer more fully. As someone said, the available analyzers have been discussed a lot here. You might try a search for more info here, or start a new thread asking for help finding an analyzer that meets your specific needs.

Cheers.

 

[grf88]

Good info here. Thank you.

How sensitive are the CO meters to storage? Do they easily go out of calibration? I'm not lucky enough to be a frequent diver. A few times a year is all I can do. I'm wondering if buying a meter would still be smart or would it be unreliable after a few uses and long storage periods.

If you are only diving a few times a year this product will give you a low cost option. Not as convenient as as more expensive equipment but for less than $10.00 you can protect yourself.
DRIS Dive Gear Carbon Monoxide Test Packet | Dive Right In Scuba - Plainfield, IL - Dive Right in Scuba

 

[boulderjohn]

I just finished my PADI O/W course and I haven't heard the word Carbon Monoxide/CO even mentioned (in relation to scuba) until now. Thanks for the post

I guess the general practice is to assume reputable dive shops have clean air.

I took the book course and it was never mentioned by my instructor. I'll look into a CO tester

Knowledge Review 4, Question 2.

In order to get it right, you should have had to read the part of the book that talks about carbon monoxide. Did you get it right? If not, why did your instructor not straighten you out?

Knowledge Review 4, question 6.
It is about the symptoms for decompression sickness, but the wrong answers include a choice for the symptoms of carbon monoxide poisoning, which was covered in the book.

 

[swamp diver]

Good info here. Thank you.

How sensitive are the CO meters to storage? Do they easily go out of calibration? I'm not lucky enough to be a frequent diver. A few times a year is all I can do. I'm wondering if buying a meter would still be smart or would it be unreliable after a few uses and long storage periods.

Surprisingly some of them like the Analox had very stable sensors where you could store it for six months, turn it on again, bump check the unit with calibration gas and find that it was bang on. Initially I'd calibrate my Analox unit every 6 months but found that a one year calibration was fine. Unfortunately Analox has discontinued production of their CO E11 so unless you can find one real cheap I wouldn't go that route. The sensors will be available though until July 2016.

Here are the other options.

1) Oxycheq

Good unit which they claim does not need calibration which is not the case. I'd at least put some calibration on the sensor once a year in order to ensure it has not drifted and remains accurate.
OxyCheq - OxyCheq Expedition CO Analyzer w/ Alarm

2) Nuvair

This unit is an interesting one as it does appear not to need calibration. I'm not entirely sure all the ins and out of the self-calibration circuit but there is apparently a reference cell of CO in the unit against which it verifies the sensor on start up. I have not used this unit but do have the CO2 analyzer which uses a similar technology.
Carbon Monoxide Analyzer - Pro CO Alarm

3) RaeSystems ToxiRae 3 (no not purchase the ToxiRae 2 as it will not read from 0 to 3 ppm)

This is a disposible unit if purchased in North America. If purchased in SE Asia the sensor can be replaced in Singapore. That being said my sensor is on its 5th year now and still going strong. Cost about half of the two units above, however one must have a source of calibration gas and regulator because it will ask for a calibration after 6 months. With this unit you'll have to purchase some sort of flow restrictor such as the BC one found on Nuvair's site.
ToxiRAE 3 | RAE Systems

4) BWT GasAlert Extreme

Expensive and again you will need calibration gas and a regulator. I can't recall but I think it will request a calibration at a maximum six month interval. After that it starts to chirp at you or at least flash calibration needed.
GasAlert Extreme Single Gas Detector


The Analox unit was the best of the bunch IMO but you'll have to go for the Oxycheq or Nuvair at this point.

The SensorCon was a unit previously available but the manufacturer has discontinued the scuba option. This unit's sensor was very sensitive to over-pressurization and one had to find a way to deliver gas at a flow of only 0.5 lpm to the sensor. Higher than that and one would get a false positive reading.

 

[dreamdive]

BTW, I know it's still a bit far off, but at this year's DEMA, one of my lectures will be on CO.

 

[victorzamora]

Wikipedia describes standards for open air environments maxing out at 50-100ppm before evacuation is required but cite time and barometric pressure (ATA 1 in open air) as forces that compound the risk.

The scariest one, to me, is that not only does CO become increasingly deadlier as you go deeper, it then starts getting deadlier again as you go shallower. So, the partial pressures of the gases you're breathing gos up as you descend and go down as you ascend, right? That means that your ppCO is going up as you go down. The physiology of that is that the CO is getting absorbed more rapidly into your bloodstream. CO in your blood prevents O2 from bonding. But at those depths, your ppO2 is elevated as well. When you start ascending, your ppO2 drops dramatically.....but the CO attached to your blood cells stays there. This makes you less tolerant of the CO in your system, making ascent the deadliest time of a CO hit, if you haven't died already.

I just finished my PADI O/W course and I haven't heard the word Carbon Monoxide/CO even mentioned (in relation to scuba) until now. Thanks for the post

I guess the general practice is to assume reputable dive shops have clean air.

As has been mentioned before, this is VERY bad general practice. Fill stations that cater to cave divers and tech divers are the most proud of their work, and they have to be. With the depths and penetration involved, cave and tech divers are VERY serious about their gases. One of the most respected fill stations in Cave Country had a very bad CO incident recently. Nobody got hurt, but it was caught early through analyzers....and every tank was recalled, banks were dumped, and a lot of money was lost. Fill stations in Mexico with double-fancy-inline-CO-shutoffs and SUPER regular air checks still have CO events. I found one tank with 5ppm in Mx, and I dove it but reported it to the shop. They analyzed every tank (literally hundreds, if not thousands) as well as all of their banks. They confirmed my analysis, emptied it out, O2 cleaned it, re-filled it, and apologized/thanked me profusely. CO happens. It can happen in the blink of an eye, even with fancy filters and shut-offs and all-electric compressors.

---------- Post added April 20th, 2015 at 09:35 AM ----------

The SensorCon was a unit previously available but the manufacturer has discontinued the scuba option. This unit's sensor was very sensitive to over-pressurization and one had to find a way to deliver gas at a flow of only 0.5 lpm to the sensor. Higher than that and one would get a false positive reading.

The scuba option is a total waste, it absolutely sucks. The hardware in it is absolute garbage. However, the overpressure sensitivity is real. There are ways around it, but it's certainly an issue. It's good for as cheap as it is, $119 from Sensorcon directly, but I'm currently looking elsewhere to replace mine.