Carbon monoxide found in tanks

[Nirvana]

I went diving this past weekend and, as I have been doing for a while know, I took my CO analyser with me. I was diving with an OP I trust and did not expect to find any trace of carbon monoxide. Still, I went on and tested the tanks.


First, it was my buddy's tanks (doubles) that were analysed. No carbon monoxide found. Then I went for mine. The device started to beep and indicated 18 ppm. I repeated the tests on both sets of doubles, with the same results. I talked to the OP manager and tested two other sets. The first red 7 ppm and the other, 0. The manager apologised and asked for my analyser to check other tanks. Some time later, he came back to me and said he believes the contaminated tanks were a group of five that had been on lent for another OP. Still, he promised to go over the OPs procedures regarding CO control.

What really surprised me that day was my experience with another diver setting up beside me, who I believe to be and instructor. When I detected CO in my tanks, I told him that and offered my analyser for him to check his gas. He told me he couldn't smell anything strange in his tanks and said he did not want to use the analyser.


edit: spelling

 

[Jcp2]

Carbon monoxide is odorless.

 

[Lorenzoid]

Carbon monoxide is odorless.

Many people assume they can detect it based on the odor of other products of the combustion that produced the CO, but--and I'm not an expert here--I believe whether one could detect those other products by odor would depend on what kind of combustion was involved. In my naive mind, I picture a compressor intake too near a diesel exhaust, but in the real world that's probably rarely what happened. In some instances there could, I suppose, be a relatively high level of CO and a relatively low, perhaps undetectable to most humans, level of odor from other combustion products.

 

[Sam Miller III]

On June 4th 1960- 59 years ago my room mate and fellow diver passed away from CO poisoning
diving to 160 feet deep off Alligator point Catalina Island

We were in the process of salvaging a 7000 pound anchor from 105 feet

The anchor is now on display out side at the Marine museum at San Pedro California

CO is a Killer
SDM

@drbill

@Marie13 CE

 

[rjack321]

Many people assume they can detect it based on the odor of other products of the combustion that produced the CO, but--and I'm not an expert here--I believe whether one could detect those other products by odor would depend on what kind of combustion was involved. In my naive mind, I picture a compressor intake too near a diesel exhaust, but in the real world that's probably rarely what happened. In some instances there could, I suppose, be a relatively high level of CO and a relatively low, perhaps undetectable to most humans, level of odor from other combustion products.

You're on the right track but diesel engines rarely produce CO. Gas engines produce quite a bit, usually in the 500-1500 ppm range for a properly operating engine. More if a spark plug is fouled or the engine needs tuning.

Of course another big source is the compressor itself. If mineral oil is used and its run hot you get partial combustion and CO.

 

[DandyDon]

I was diving with an OP I trust and did not expect to find any trace of carbon monoxide. Still, I went on and tested the tanks.

It can be boring to test for CO when you just keep getting zero readings like you're supposed to, until you get your first significant positive reading! Then it just becomes routine, regardless of whether you ever see anyone else test or not.

What really surprised me that day was my experience with another diver setting up beside be, who I believe to be and instructor. When I detected CO in my tanks, I told him that and offered my analyser for him to check his gas. He said he couldn't smell anything strange in his tanks and said he did not want to use the analyser.

He could be a master instructor and still ignorant of CO risks or what to watch for? He was clueless. The dive training agencies and even DAN continue to fail to teach appropriate warnings or even conduct studies. They claim that they don't recognize the problem, but who knows how many cases of travelers flu were really non-lethal hits, or how many scuba drownings were causes by tainted gases in tanks there were never tested, or just hidden to protect business.

I picture a compressor intake too near a diesel exhaust, but in the real world that's probably rarely what happened.

I think hot compressors burning their own lubricating oil is the more common source. Using the correct filters and changing appropriately can help prevent that risks, but shortcuts happen.

 

[Rusty Shackleford]

On June 4th 1960- 59 years ago my room mate and fellow diver passed away from CO poisoning
diving to 160 feet deep off Alligator point Catalina Island

We were in the process of salvaging a 7000 pound anchor from 105 feet

The anchor is now on display out side at the Marine museum at San Pedro California

CO is a Killer
SDM

@drbill

@Marie13 CE

Did you ever determine the cause for the elevated CO?

 

[rjack321]

I think hot compressors burning their own lubricating oil is the more common source. Using the correct filters and changing appropriately can help prevent that risks, but shortcuts happen.

I don't have any data but suspect this as well. Many compressors are still using mineral oil which has a low flash point.

Another thing to think about is that compressors are really just super high compression diesel engines without a fuel injection system. But the oil itself, especially when hot, can act as a fuel.

 

[drk5036]

I have no point of reference here; what will 18 ppm do if you breath it during a dive?

 

[Lorenzoid]

. . .
Of course another big source is the compressor itself. If mineral oil is used and its run hot you get partial combustion and CO.

That's just what I was getting at. I'm now guessing that partial combustion of mineral oil may not produce the odor or amount of odor that those of us who are less knowledgeable about such things might expect. We associate the "CO odor" with engine exhaust, etc.--things we're familiar with from everyday experience--when in reality the odor of partially combusted mineral oil might be something different or otherwise not readily detectable by our sense of smell. Anyway, my rambling just underlines what we here all know: you can't rely on odor to detect CO.