Carbon monoxide from compressors?

[pescador775]

I'd like to hear from anyone who has info: is there any evidence for carbon monoxide being produced by air compressors and, if so, are there any documented accidents/incidents? I'm pretty sure that this would be a rare occurence but there is enough of a buzz around to arouse interest. Subscribers, writers of "Undercurrents", a little help? Below is a link which speaks to the subject. Sorry, only the abstract at this time.

http://www.ncbi.nlm.nih.gov/entrez/q...533&query_hl=1

[FFMDiver]

I found the article. The Canadian study admits that the statistics were weak. I found the sample size too small and the methodology was poorly planned (non-randomized ANOVA a big no-no, no power or effect size...etc etc) still, it points to an event where some CO was found in alarming amounts in some fire station bottles.

[cowjazz]

It can, and does happen. If the compressor breaks or malfunctions, oil and CO will contaminate the breathing gas. Considering the number of tank fills, and the number of contaminated air incidents reported, I'd say it is a rare occurance.

You are in serious trouble once you start absorbing CO under pressure at depth, and the oil contaminates coat your lungs preventing oxygen absorbtion.

I've never had "bad air", but I have seen the consequences.

I have been told you might notice a slight detergent taste when you breath through your regulator. Would our more knowledgeable members please describe the taste and smell of "bad air"? I've been told that if you are not familiar with "bad air", then you might not recognize the problem.

[reefraff]

CO is not a product of compression, though it is extremely dangerous to divers. Even a little bit is dangerous and the impact is magnified with depth. It's not a common problem but, when it is a problem, it can easily cause serious permanent injury or be fatal. Though responsible shops will test their gas regularly, I am not aware of any mandatory reporting requirements which means there isn't a reliable single source for statistics regarding CO issues in SCUBA.

The source for CO in a scuba cylinder is usually a gas driven engine powering the compressor. Great care needs to be taken to keep the compressor intake away (and upstream) from the exhaust of any internal combustion engine.

[reefraff]

I have been told you might notice a slight detergent taste when you breath through your regulator. Would our more knowledgeable members please describe the taste and smell of "bad air"? I've been told that if you are not familiar with "bad air", then you might not recognize the problem.

CO is an odorless, tasteless gas which means you can't smell or taste it. Nonetheless, the presence of CO is usually associated with the exhaust from internal combustion engines and the taste or smell of hydrocarbons is much easier to detect. Think of that kind of sickly sweet tailpipe smell when you first start your car on a cool morning and you'll have an idea of what to look for - though greatly diluted.

[cowjazz]

Thanks Reefraff, good information.

[pescador775]

Guys, take a look:

http://www.cdnn.info/news/industry/i050529b.html

This article describes a lawsuit for "bad air".

Freebie: pic of "Miss Universe"

[Vayu]

I've never seen this however I've heard it can happen. The compressor components have to be inspected after a period of time and your LDS would keep a log of this. "Bad air" is any gas mix that may contribute to an accident. The combination of depth, technical mixes, and human error is probably a greater hazard to divers than carbon monoxide.

Even though the compressor is closed, I would avoid ones situated in trucker parking lots or garages. Don't leave your car on and avoid smoking when doing gas fills. This all may seem obvious, but I bet there is someone out there doing this very thing.

Though I havn't seen the direct effects of monoxide poisoning, I have seen a tank blow up; this is also a much more common contributor to injury.

-V

[bigchrisb]

I have a small compressor, and also access to a portable gaseous mass-spec from work, that I regularly test my compressor output with. So far, I have not detected any elevated levels of CO. Generally, the samples I test from my compressor have between 1 - 1.5 ppm CO, which is in line with the ambient air where I'm running the compressor.

I have picked up other issues with the compressor output from time to time - to see the impact of not changing the filter media, I left the filters run longer than usual without a change, monitoring the gas output regularly to see the effects. After about 3 times my usual media change interval, the level of liquid hydrocarbons (oil) in the output air began to rise slightly, suggesting that the media had saturated. I suspect that this is from the filter media becoming saturated with the trace oil residues that make it though the coalescor.

Of course, once I started to notice an increase in the contaminant levels in the gas tests, I changed the media. Whilst it might be interesting to see the trends in contaminants, I'd rather not breathe the stuff, nor spend hundreds of compressor hours pumping non-breathable gas.

[RoatanMan]

I'd like to hear from anyone who has info: is there any evidence for carbon monoxide being produced by air compressors and, if so, are there any documented accidents/incidents? I'm pretty sure that this would be a rare occurence but there is enough of a buzz around to arouse interest. Subscribers, writers of "Undercurrents", a little help?

This was something we used to be routinely worried about in the 60's and 70's... so much so that most filling stations are keenly aware of this. The reason back then was that the compressors were powered by gasoline engines. Stories, documented and otherwise abound from that era.

I would be much more concerned about: a) external environment issues (idling trucks, garbage fires, etc as mentioned above) or b) oil infiltration from the compressor itself. Oil imparts what some recognize as a "plastic or burned plastic" smell to the air.