Continued Carbon Monoxide - Cozumel

[bleeb]

Any idea how 100 ppm translates into percentage of CO, say at the surface?

Not quite sure what you're asking.

Taken literally, 100 ppm = 0.01%.

OTOH, to paraphrase what others have previously tried to convey, if your setting your nominal ppCO tolerance to be the equivalent of 100 ppm at 4 ata/99 fsw/10 msw, then the ppCO measured on the surface has to be <25 ppm/0.0025%.

 

[cruiser]

Not quite sure what you're asking.

Taken literally, 100 ppm = 0.01%.

This is what I was wondering, thanks.

OTOH, to paraphrase what others have previously tried to convey, if your setting your nominal ppCO tolerance to be the equivalent of 100 ppm at 4 ata/99 fsw/10 msw, then the ppCO measured on the surface has to be <25 ppm/0.0025%.

I understand how the CO reading you get at the surface will multiply according to depth. What may be a tolerable ppm reading at the surface may not be tolerable at depth. So if you're out on a dive boat and getting readings of 15 ppm, I would say you do not want to dive with that tank and go deep (or maybe that's just me).

 

[bleeb]

I understand how the CO reading you get at the surface will multiply according to depth. What may be a tolerable ppm reading at the surface may not be tolerable at depth. So if you're out on a dive boat and getting readings of 15 ppm, I would say you do not want to dive with that tank and go deep (or maybe that's just me).

Not just you. If anything, the levels specified by various government agencies are significantly lower, for example:

I'd use the NIOSH limit at 35 ppm or better yet the ACGIH's TLV at 25 ppm as they update their limits much more frequently based on the current science available.
25 ppm/5 ATA = 5 ppm maximum in the tank for recreational diving.

 

[Quero]

Thanks to Don's persistence of keeping the subject of CO testing in the forefront, I've bought an Analox Portable CO tester. Got a Pelican box for it today.

Where did you get it? The Analox website says the product is not available for purchase?

 

[DandyDon]

The other diver with a surviving CO tester rejoined us today and on the way to Cathedral dive site we got 17 ppm on 3 out of 4 tanks. I've said I would not dive over 15 ppm, but since we are both in the learning stages of calibrating and testing - we chose shallower sites instead. We'll know more when he gets home and tests his tester on his calgas, which he could not fly. However accurate these tests may or may not be, they are not just making up figures; there is measurable CO in the tanks. We'll know soon if the tester could have been off some.

I understand how the CO reading you get at the surface will multiply according to depth. What may be a tolerable ppm reading at the surface may not be tolerable at depth. So if you're out on a dive boat and getting readings of 15 ppm, I would say you do not want to dive with that tank and go deep (or maybe that's just me).

It's more complicated than that, having to do with blood gases, hemoglobin, cumulative build up, etc.

Where did you get it? The Analox website says the product is not available for purchase?

It's available for sale only in the US as various countries have various restrictions on trade, approval of technical gadgets, etc - but you can buy it online in the States, then have it shipped to you, maybe. Ask patti.clarkson@analox.biz

 

[cruiser]

Where did you get it? The Analox website says the product is not available for purchase?

Quero--

Their web site leaves a lot to be desired.

You can contact Patti directly at patti.clarkson@analox.biz. She'll answer all your questions and then some

 

[Quero]

It's available for sale only in the US as various countries have various restrictions on trade, approval of technical gadgets, etc - but you can buy it online in the States, then have it shipped to you, maybe. Ask patti.clarkson@analox.biz

Not a problem. I have a US address where I get all sorts of stuff I don't trust to make it to me (at least in a timely way) via Thailand Post

Quero--

Their web site leaves a lot to be desired.

You can contact Patti directly at patti.clarkson@analox.biz. She'll answer all your questions and then some

Thanks to both of you. I've sent off a request for details.

I already own an Analox Nitrox analyzer, and have been quite satisfied with it. I figure that as long as I have to get replacement sensors for one of their products, it makes sense for me to stick with the same company assuming the CO detection device is reliable.

 

[RubberDucky]

I'm getting ridicule from one Coz local in PMs, but he won't post in public here for open examination of his arguments - and I won't copy & paste those even anonymously.

It's always the willfully ignorant that want to ridicule others for trying to make a difference. Having personally tested a tank in Cozumel that averaged ~30 ppm of CO (it peaked at 43 ppm), I would not hesitate to recommend CO detection to anyone. That wasn't long after another dive op in Cozumel unintentionally poisoned a double digit number of divers with bad air.

It's one thing to bury your head in the sand and pretend like the risk isn't there, but it's another thing to ridicule someone trying to help keep people from, you know, dying. I have a relative who went unconcious underwater while diving once (in Egypt, I think?). No one ever knew why that happened to her, and only through OPEN discussion on these forums did I come to realize what the cause possibly was (she's fine btw, but stopped diving as a result).

Bottom line: if you run a dive op and spend your time privately criticizing those who selflessly work to spread awareness and help others instead of demanding CO detection from your local fill station.. I can't really say what I want here without breaking a rule or 3, so I'll just leave it at that. Shame on you.

 

[swamp diver]

It's always the willfully ignorant that want to ridicule others for trying to make a difference. Having personally tested a tank in Cozumel that averaged ~30 ppm of CO (it peaked at 43 ppm), I would not hesitate to recommend CO detection to anyone.

Given the number of independent recurrent serial reports of CO contamination in the compressed air on Cozumel one really has to wonder what the problem is down there? Is there a compressor issue at the island's central compressed air supplier or is this problem from several different suppliers? Last I heard the island's central compressed air manufacturer supplied about 80 percent of the compressed breathing gas for divers on Cozumel.

Unlike the food industry where the finding of E.coli 0157 in hamburger meat or Salmonella enteritidis in eggs would see the regulator step in immediately to investigate the faulty manufacturing process which resulted in the product becoming contaminated in the first place, the dive industry has no such regulator and as a result the compressed air product manufacturers are able to carry on despite recurrent CO contamination identified by end users. Even in Mexico there are probably more regulations for restaurants pertaining to the safe preparation of food than there are for fill stations on how to produce contaminant-free compressed breathing air.

PADI has decided to absolve itself of any responsibility to ensure its affiliated shops and resorts must follow a compressed air quality standard (policy change in 2009) and now defers to the local authority having jurisdiction which in most tropical dive regions does not exist. As a result it currently behooves individual divers to carry portable self-protection devices to rule out CO contamination of their breathing gas prior to getting wet.

Salmonella or E. coli in one's food might might result in a bad case of diarrhea or rarely kidney failure in the case of E. coli 0157, but odorless carbon monoxide contamination in one's dive air has the potential to injure or kill a diver with little warning while underwater.

 

[InTheDrink]

On a recent liveabord trip in Egypt my Pocket CO was getting several readings of 7-8 ppm CO. I mentioned this several times to the guides and asked them to check the intake and asked to see the compressor.

I never got to see the compressor but they did *something* and the readings I got thereafter were 0-1 ppm.

So just having the tester with me was enough to get them to fix the problem, whatever it was. So carrying the device can definitely be worthwhile. And as a point to note the device (pocket co) was at 0 before placing it in the bag of tank gas an did return to 0 shortly after taking it out of the bag with the tank gas in it so there wasn't any cross contamination.

J