Acceptable CO Level?

[hunabku]

Some of you smarter than I am guy's take a look at this http://www.epa.gov/airtrends/carbon.html Seems normal atmospheric levels of CO is pretty significant?

The EPA station shown in Jacksonville near the I10-I95 interchange is next door to my office. It is literally on the side of the road from an exremely busy, back up prone, major highway interchange.

I am running an oxycheq unit and I usually get a 0 or a -.01

[a64pilot]

I think this is from that location http://www.epa.gov/airtrends/carbon.html#coloc Still, it seems a pretty safe assumption that the national average for CO is around 2 PPM, so these instruments should read about 2 PPM with just normal atmospheric air, IF that is true. It may be that they are calibrated to read normal levels as 0 PPM though, or it may mean that normal atmospheric levels are not resolvable by these instruments?
I don't have any issue with this at all, I don't own one, don't work for anyone that manufactures or sells them. Just I think that 1 PPM accuracy may take a lab type instrument that's calibrated to NIST standards and lives a protected life to achieve repeatedly.
Look at it this way, I can buy many tire pressure gauges that read to .1 PSI, but I don't think any of the cheaper ones are accurate to .1 PSI, just because they display it, doesn't mean they are that accurate.

On edit, I don't think 0 PPM of CO is achievable from diving gasses, not at least economically anyway, I think to truly get to 0 PPM, all the gases would have to be liquefied and fractionally distilled? Or is there some type of chemical that would filter out CO, like sorb does CO2?

[Sludge]

Maybe it's 0 ppmg?

[a64pilot]

I'll bite, what's the G ?
Next time we meet, remind me to tell you my PSI joke, it won't work in print though.

[Sludge]

As in psia vs psig. Absolute vs gauge.

[hunabku]

Or is there some type of chemical that would filter out CO, like sorb does CO2?

I believe part of the standard filter process for breathing gas compressors is a filter material that converts CO into CO2.

Hopefully the opererator of a compressor can chime in.

[a64pilot]

I do test flights with this CO detector http://argus-hazco.com/gas-section/s...mini-sa-co.htm it's "zeroed" before flight so that whatever ambient level of CO is, it's displayed as 0, it's any increases of CO level that I'M concerned with.

The joke is
What's PSI?
What's PSIA?
What's PSIG?
What's PE-PSI?

[Jim Wyatt]

So my question is, for those of you who have been using CO analyzers;

What levels are you "normally" finding?

What, if any do you find "acceptable"?

I was initially under the impression that zero was the only "acceptable" level, am I expecting too much?

Thanks for your input.

Zero in compressed air.

A properly maintained compressor filter has a chemical called Hopcalite in it. So long as the ambient temperature is below 120 degrees F the hopcalite will convert CO into CO2. Hopcalite is a catalyst and works so long as it is dry and below 120 degrees F.

[Randy Thornton]

Dive Addicts' fill station is in the process of building a container where we dump all of our used Sofnolime from CCR dives. The theory is that we will run our intake for the compressor through the used Sofnolime to remove any CO2 that is in the air to start with. That way, any additional CO2 that is added to the gas via the filtration system will hopefully be somewhat minimal. There are days in the Salt Lake Valley when the CO2 level is quite high to start with, so our hope is that this process will reduce both CO2 and CO levels after having gone through both the Hopcalite and the Sofnolime filtration. The Sofnolime portion is not complete yet, so I'll let you know how it goes after we try it.

[rjack]

Zero in theory.
In practice you can get 3ppm just breathing on an analyzer. I would dive anything less than 3ppm especially if I made the gas in the first place and know its provenance. More than 3ppm, particularly if its a gas I am using quite deep would be cause for concern.

My O2 regularly reads about 6-7ppm since CO is a trace contaminant of cryogenic O2 production. Its removed by my compressor filter when continuous blending. And diluted to non-detectable levels when doing most partial pressure blending. Boosted O2 for deco does have 6-7ppm in it though. I am fine with that since I'm not breathing that gas deeper than 20ft anyway.