Home fill station for dummies?

[Robbyg]

The PSA machines concentrate to essentially 4.5x everything in the atmosphere except nitrogen. As far as partial pressures are concerned when breathing at the surface, that is equivalent to diving air at 120ft.
If you're using it for "pure o2" for decompression, then it's comparable to diving air at 200ft. Anything mix wise when using it for nitrox is somewhere in between.

While I certainly don't advocate diving air to 120ft or especially to 200ft, it is not due to any effects of the trace gases in your body, and everything to do with gas density and CO2/N2 narcosis.

We do use oxygen analyzers and some use carbon monoxide analyzers for normal diving, and in technical diving we will use helium analyzers, but those are the only gases we ever measure.

Thanks for the reply. I started reading more on the PSA machines and I noticed that they filter out the Noble gases as they concentrate o2. When I was younger and really into diving all of this stuff was kind of talked about but it seemed like something that was so far out there that only major commercial operations could access it. It's pretty cool to see that divers today are able to DIY their own systems. As a guy who is into the technical side of this heavily, do you recommend that regular air diver get a CO meter?

 

[tbone1004]

Thanks for the reply. I started reading more on the PSA machines and I noticed that they filter out the Noble gases as they concentrate o2. When I was younger and really into diving all of this stuff was kind of talked about but it seemed like something that was so far out there that only major commercial operations could access it. It's pretty cool to see that divers today are able to DIY their own systems. As a guy who is into the technical side of this heavily, do you recommend that regular air diver get a CO meter?

how long ago was that? PSA machines have been in use in home oxygen concentrators for a very long time.

I HIGHLY recommend that ALL divers get a CO meter. Regular divers are arguably at higher risk because they tend not to be as picky about who does their gas fills. You have no idea if the fill station has a CO meter/alarm on it *hint, the VAST majority do not*, and if you travel it is that much more important because you don't have a good history of the operation and how good they are about maintenance and getting air checks, etc.

 

[Miyaru]

...
do you recommend that regular air diver get a CO meter?

Yes!
Quite a while ago, I ordered hopcalite for a mobile, gasoline driven compressor.
It's a catalyst with a really long lifetime as long as it stays completely dry. Hopcalite turns CO into CO2 and when doing so, the hopcalite gets hot.

Since I had to order a minimum quantity, I used to remaining hopcalite in another filter housing and placed it between the stationary compressor and the banks. One evening, while the (electric) compressor was running, the filter housing with hopcalite was hot. Almost too hot to keep touching.

Cause: barbecue at the neighbors. I could hardly smell it. The CO meter detected it, the hopcalite turned it into CO2.

 

[Robbyg]

how long ago was that? PSA machines have been in use in home oxygen concentrators for a very long time.

I HIGHLY recommend that ALL divers get a CO meter. Regular divers are arguably at higher risk because they tend not to be as picky about who does their gas fills. You have no idea if the fill station has a CO meter/alarm on it *hint, the VAST majority do not*, and if you travel it is that much more important because you don't have a good history of the operation and how good they are about maintenance and getting air checks, etc.

I was seriously into Spear Fishing via Snorkeling 2-4 days a week 6 hours per day out at sea from 1975-1985. Got in lots of good free diving and developed pretty good breath holding skills and since I was typically alone I learned not to panic no matter what. The last 3 years of that period I was Scuba Diving and of course out at sea for much shorter periods of time each day.

Later on because of work I could only dive a maximum of once every other weekend from about 1985 until about 2004. I then took a break in 2004 after myself and two other divers almost got killed. I was diving again occasionally from 2008 until 2016 when I took another break. I am just now getting back into the Hobby again. I was not the kind of person to follow diving on a forum until Covid struck, I just kind looked at new gear that was on the Dive boat.

I agree with everything you said about CO. I have a very expensive Co2 meter that I used for a design project but I don't have a CO meter. I will have to buy one. What do you recommend that is not super expensive but is accurate?

 

[Robbyg]

Yes!
Quite a while ago, I ordered hopcalite for a mobile, gasoline driven compressor.
It's a catalyst with a really long lifetime as long as it stays completely dry. Hopcalite turns CO into CO2 and when doing so, the hopcalite gets hot.

Since I had to order a minimum quantity, I used to remaining hopcalite in another filter housing and placed it between the stationary compressor and the banks. One evening, while the (electric) compressor was running, the filter housing with hopcalite was hot. Almost too hot to keep touching.

Cause: barbecue at the neighbors. I could hardly smell it. The CO meter detected it, the hopcalite turned it into CO2.

That is an interesting story and begs the question, I have a SAN-10 Co2 monitor, I wonder if I could use hopcalite with it to get a CO reading?

 

[tbone1004]

I was seriously into Spear Fishing via Snorkeling 2-4 days a week 6 hours per day out at sea from 1975-1985. Got in lots of good free diving and developed pretty good breath holding skills and since I was typically alone I learned not to panic no matter what. The last 3 years of that period I was Scuba Diving and of course out at sea for much shorter periods of time each day.

Later on because of work I could only dive a maximum of once every other weekend from about 1985 until about 2004. I then took a break in 2004 after myself and two other divers almost got killed. I was diving again occasionally from 2008 until 2016 when I took another break. I am just now getting back into the Hobby again. I was not the kind of person to follow diving on a forum until Covid struck, I just kind looked at new gear that was on the Dive boat.

I agree with everything you said about CO. I have a very expensive Co2 meter that I used for a design project but I don't have a CO meter. I will have to buy one. What do you recommend that is not super expensive but is accurate?

Palm CO Carbon Monoxide Analyzer

Not cheap, but unfortunately the Cootwo is not available anymore

 

[Miyaru]

That is an interesting story and begs the question, I have a SAN-10 Co2 monitor, I wonder if I could use hopcalite with it to get a CO reading?

No, the carbon dioxide elevation would be minimal, compared to the allowed 500ml/m3 in safe air. See EN12021 for the specs.

Stick a temperature sensor onto the hopcalite filter housing, much more effective!

 

[Miyaru]

Palm CO Carbon Monoxide Analyzer

Not cheap, but unfortunately the Cootwo is not available anymore

Nitrox/Trimix & CO analyzer

 

[tmassey]

https://envirosupply.net/products/rae-systems-toxirae-3

Not designed for scuba, but I’ve used it quite effectively for the last three years.

 

[Robbyg]

The Palm CO looks really nice and would be the best choice but it is a bit to pricey for me.
The Arduino system is a very cool design but I am kind of looking for something portable and durable. It would be really nice if somebody makes that into a kit and supplies a proper housing for it.
I see stuff on Amazon but I have no idea if any of those cheaper meters are any good, or good enough that they could be used for Diving applications.
Sorry for taking the thread off topic and thanks to everybody for their suggestions, especially @tbone1004 .