I found CO in tanks

[49north]

We just aborted a dive this morning. We analyzed our tanks with a Palm CO analyzer and found all of the air tanks contained between 6 and 7 ppm. The ambient air read 0 and the nitrox tanks read 0. The dive op said it was our analyzer because the compressor was serviced 22 hours ago. Hmmm...

They offered to give us nitrox, but one member of our group was not nitrox certified, so we declined.

I feel we made the right call. Breathing gas should not have any CO. There doesn’t seem to be any firm numbers as to what is acceptable, but it seems the consensus on this board is 5ppm max.

Does anyone have any thoughts on our decision?

 

[kelemvor]

Good call not diving the contaminated tanks. I know some advocate diving with low levels of CO but personally my limit is 0.

However, I would have taken the nitrox - presuming they would have allowed the uncertified diver to have it. I think the separate class is a bit of a scam and there isn't really a ton of knowledge needed to use it safely. The necessary information could have been imparted right on the boat.

Also, if the fill station is denying they have a problem you really should share the details about who it is. I'm sure you wouldn't want any guilt associated with it if there was something to occur and you didn't do your best to disseminate the risk.

I found 1ppm in my tanks once and the fill station "rebuilt" their whole filter system as a result. I think that's an appropriate response for a fill station to have upon receiving a report of CO contamination coming from their equipment.

 

[Marie13]

Just curious...are you diving locally? And have you gone with this dive op before?

 

[Dogbowl]

Maybe your analyzer wasn’t working right...
Maybe 6 or 7ppm is “acceptable”...

But I think you made the right decision. Not worth risking your lives.

Where did this happen? No names needed.

 

[guruboy]

Does a different compressor pump the nitrox? If not, those tanks are also susceptible to CO contamination.

 

[49north]

Just curious...are you diving locally? And have you gone with this dive op before?

We were not diving locally and have not used this dive op before.

Maybe your analyzer wasn’t working right...
Maybe 6 or 7ppm is “acceptable”...

But I think you made the right decision. Not worth risking your lives.

Where did this happen? No names needed.

If the analyzer wasn’t working right, then it probably shouldn’t have read 0 on the nitrox tank.

I don’t want to point fingers or name names, but it was in the US.

 

[49north]

Does a different compressor pump the nitrox? If not, those tanks are also susceptible to CO contamination.

I didn’t ask, but I got the impression that they have a separate compressor for nitrox.

 

[tbone1004]

at 6-7ppm I wouldn't have dove them, but at 3-4 I would have. Hell if you're a smoker you're going to have more than that in your body anyway.

I'm not a stickler for 0ppm depending on the compressor. I.e. a stock rix will never put out 0ppm air because it's in ambient air and it doesn't really have "filters" just coalescers that won't remove any CO. My O2 generator has CO in it as well because it's not removed during the adsorption process and it will show a bit more than ambient CO.

Now to the dive op, whether it was serviced or not, doesn't mean that something didn't go wrong and CO didn't get through the filters. It is quite possible it did, and they need to check it out and validate with another CO analyzer if they don't believe yours

 

[Stoo]

I believe you made the right call as well. It is interesting that the industry hasn't clearly defined what an acceptable level of CO is in a tank, so defaulting to "0" is reasonable. I have detected trace amounts... like .01... and dove. Ambient air will often contain that amount, especially in urban environments.

Regarding "naming" the operation, you are correct not to do so. You don't specify if these are your own tanks or rentals. If rentals, they may have been filed elsewhere while being used. If they are your own tanks, then you will obviously want to be certain that your tanks weren't already dirty.

Presumably the shop is checking out their system now... Hopefully.

 

[49north]

at 6-7ppm I wouldn't have dove them, but at 3-4 I would have. Hell if you're a smoker you're going to have more than that in your body anyway.

I'm not a stickler for 0ppm depending on the compressor. I.e. a stock rix will never put out 0ppm air because it's in ambient air and it doesn't really have "filters" just coalescers that won't remove any CO. My O2 generator has CO in it as well because it's not removed during the adsorption process and it will show a bit more than ambient CO.

Now to the dive op, whether it was serviced or not, doesn't mean that something didn't go wrong and CO didn't get through the filters. It is quite possible it did, and they need to check it out and validate with another CO analyzer if they don't believe yours

I would have been ok with 3-4 as well.

I agree, who’s to say that something didn’t go wrong with the compressor right after the air sample was sent in?

I am surprised that shops (at least in Canada and the US) don’t have inline analyzers.