Rix intrinsic safety regarding CO

[2airishuman]

I'm getting pickier about my air fills and have started having some more detailed discussions with the LDSs about their compressor maintenance practices.

One LDS uses a Rix compressor, and asserted in discussions with me that these compressors don't produce CO, are not capable of producing CO even when they are failing, and do not pose an overheating risk because they are water cooled and thermally protected.

The shop went on to say that because they are in a freestanding building with no other tenants, and have a rooftop air intake for the compressor, that there is no plausible means by which their air could become contaminated with CO. They test quarterly using a lab but do not have continuous surveillance for CO.

I'm wondering how well everyone thinks this line of reasoning holds up and whether this would still constitute best practices even without continuous testing.

 

[AlexL]

constitute best practices

they can reason things out till they're blue in the face; the only way to be sure is to test every fill, no matter what the brand of compressor its being fed from.

 

[grf88]

The nature of the RIX compressor is such that there is no mechanism for the production of CO however if there is CO going into the compressor from an outside source it would be possible for it to end up in the tank. I have a filter stack on my RIX and although it is probably overkill I do have hopcalite in the filters I use. I chose a RIX for peace of mind.

 

[iain/hsm]

I would defend that position also, A Rix compressor it Not capable of producing CO
under any circumstances.

CO from the atmosphere or entrained by exhaust from a petrol of diesel engine drive is a totally different subject dont get confused here.

Rix compressors dont produce oil vapour either.

Or decompose the oil by overheating or by oxidation.

Next time your in the shop take a small glass with you and asked for a sample of the condensate drain. Then drink it.
Its pure distilled water.

Then do the same at the other dive shop using a oil lubricated compressor and take a hard look at the stinking emusified oil and water waste from their drains.

Further this oil vapour carry over coats the inside of the filter housing and with the best filtraton still ppm levels of oil vapour hydrocarbons and a host of other nasty oil decomposing compounds that you never get tested for are being dispenced into your tank each and every fill

By contrast the Rix dive shop compressor can neither add to or subtract from the original purity status of the entrained gas into the compressor. Your call. Iain

 

[Frontpointer1000]

Fascinating topic.

What is considered the standard protocol for compressor air fill monitoring?

I know that one time I was diving of the cost of fiji on a small island resort. Their compressor was breaking down nearly daily. I really wondered if we were breathing anything remotely safe. We all lived, nothing smelled or tasted funny.

How is compressed air best tested and monitored? What should I be asking dive shops when I get fills to ensure safe air?

 

[rjack321]

I would defend that position also, A Rix compressor it Not capable of producing CO
under any circumstances.

CO from the atmosphere or entrained by exhaust from a petrol of diesel engine drive is a totally different subject dont get confused here.

Rix compressors dont produce oil vapour either.

Or decompose the oil by overheating or by oxidation.

Next time your in the shop take a small glass with you and asked for a sample of the condensate drain. Then drink it.
Its pure distilled water.

Then do the same at the other dive shop using a oil lubricated compressor and take a hard look at the stinking emusified oil and water waste from their drains.

Further this oil vapour carry over coats the inside of the filter housing and with the best filtraton still ppm levels of oil vapour hydrocarbons and a host of other nasty oil decomposing compounds that you never get tested for are being dispenced into your tank each and every fill

By contrast the Rix dive shop compressor can neither add to or subtract from the original purity status of the entrained gas into the compressor. Your call. Iain

Yes it can - when Viton seals break down the resulting air quality is poor.

And not having CO catalyst on any commercial compressor is just been cheap (and foolish) entrained CO from atmospheric sources (yes even a rooftop intake) is no joke. The added cost of hopcalite is insignificant. Rix owners believing that somehow they are immune from compressor contaminants or don't need to use good filters with proper change schedule is definitely foolhardy.

I'm wondering how well everyone thinks this line of reasoning holds up and whether this would still constitute best practices even without continuous testing.

Best practice is:
1) Look for someone who's compressor installation is clean and well ventilated, heat is the number one enemy of any compressor
2) an intake remote from every plausible combustion source (i.e. the roof isn't necessarily best if there's a restaurant vent up there too)
3) quarterly air testing by an independent lab with results posted, tests should be done at the end of a filter's life not immediately after fresh filters are installed and also with a hot compressor
4) YOU to test every cylinder you use regardless of source compressor for O2 content (nitrox has been put in air cylinders by mistake more than once), CO, and taste.

Continuous monitoring of CO and moisture are nice to have but don't make up for proper installation and maintenance in the first place.

 

[2airishuman]

Thank you all who have replied so far.

Fascinating topic.

What is considered the standard protocol for compressor air fill monitoring?

Quarterly air quality checks by an independent lab.

Some compressor operators have continuous testing for CO. I understand that CO monitoring with an audible alarm is now an OSHA requirement for SCBA and SCUBA operations that fall under OSHA jurisdiction. From what I see, CO surveillance isn't yet common among recreational dive shops.

What should I be asking dive shops when I get fills to ensure safe air?

I'm not an expert, but some of the things I check on through personal observation or by asking questions include:

1) How often do they send an air sample out to an independent lab (should be quarterly)
2) Check the lab report, does the air comply with grade E? If it matters to you, is the air oxygen compatible?
3) Observe the air intake for the compressor. It should be outdoors, is it? Either way, what is nearby? Loading docks where trucks idling could be a problem at times? In a strip mall next to other tenants who may be a source of air pollution, such as an auto body shop or a restaurant? If gasoline or diesel powered, have steps been taken to separate the engine exhaust from the air intake?
4) Observe the fill station and ask questions. Are there check valves on each fill whip? If not, what is being done to prevent cross contamination from another customer's cylinder? If gases other than air are filled, what steps are taken to be sure that you get air rather than, say, 36% or 15/75? (Best practice would be separate fill stations with separate cascade banks for air and blends)
5) What about compressor maintenance and filter maintenance? Are these done per schedule, or do they push the hours to save a buck or two?
6) What is the attitude of the operators? Do they remind you of accountants and lab techs, or do they remind you of cowboys? Who do you want filling your cylinders?

 

[nadwidny]

I
Further this oil vapour carry over coats the inside of the filter housing and with the best filtraton still ppm levels of oil vapour hydrocarbons and a host of other nasty oil decomposing compounds that you never get tested for are being dispenced into your tank each and every fill

Bull. I work at a lab. Our official limit of detection is 0.2ppm for non-methane hydrocarbons and 0.4 for volatile halo-hydrocarbons but we can see them at lesser concentrations than that. If there were any oil vapour hydrocarbons present we would see them and we don't.

 

[northernone]

Bull. I work at a lab. Our official limit of detection is 0.2ppm for non-methane hydrocarbons and 0.4 for volatile halo-hydrocarbons but we can see them at lesser concentrations than that. If there were any oil vapour hydrocarbons present we would see them and we don't.

Thanks for stopping by to call methane on the post. Glad to hear the truth.

 

[kelemvor]

I'm getting pickier about my air fills and have started having some more detailed discussions with the LDSs about their compressor maintenance practices.

One LDS uses a Rix compressor, and asserted in discussions with me that these compressors don't produce CO, are not capable of producing CO even when they are failing, and do not pose an overheating risk because they are water cooled and thermally protected.

The shop went on to say that because they are in a freestanding building with no other tenants, and have a rooftop air intake for the compressor, that there is no plausible means by which their air could become contaminated with CO. They test quarterly using a lab but do not have continuous surveillance for CO.

I'm wondering how well everyone thinks this line of reasoning holds up and whether this would still constitute best practices even without continuous testing.

I had to chuckle a little. It's impossible to get CO in your tanks there just like it's impossible my servers will get hacked exposing someone's data... We do what we can to prevent it, but it's always possible something will go wrong. With an "it can't happen" attitude, you lose diligence and make it that much more likely to happen imo.

My LDS told me about a time they got CO and were having trouble finding the source. It turns out some trucker had pulled up behind their building to "rest" or something, while running his truck's engine. I assume for AC or whatever. The truck exhaust and got sucked into his intake on top of the building, and made it's way into the banks. Badaboom, badabing!

There's always a way.

Does the shop bank nitrox? I believe I've heard stories about 02 burning inside fill stations and producing CO, although I have no idea how all that plays out.


In any event, I don't bother asking fill stations how they mitigate CO risks. I bought a CO tester (originally analox, replaced with a cootwo). I test my tanks and i don't take anyone's word for if I have CO or not, I find out for myself.

I found 1ppm CO in some tanks a few months ago.. pretty sure I posted about it. It was a repeatable result. The LDS took it seriously, and changed his filters and cleaned his fill station.. I have no idea what's involved in that. However, I haven't found 1ppm co in his fills since then.

Don't guess. Don't trust the LDS. Test, and know.