Please read again and carefully your statement above from the manufacturer Coltri for the MCH 6 and ask yourself these three simple questions.
1. What part of non breathable gases do you not fully understand.
2. What part of for industrial use such as is not fully understood.
3. What part of any other use is inappropriate is again not fully understood
Unfortunately Coltri has been fairly poor in their wording with their owner manuals, in my eyes since forever.
From another passage from the same manual:
DANGER: The compressor may be used together with Nitrox mixers up to a maximum of 40% oxygen and only with certified systems that feature an alarm system and that prevent the introduction of oxygen percentages above the permitted maximum and/or incorrect mixes.
IMPORTANT: AEROTECNICA COLTRI compressors provide breathable air at high pressure in compliance with EN12021 air quality requisites.
High pressure compressor for breathing air and technical gases.
Compatible process gases:
- Nitrogen
- Helium
- Nitrox 40% max O2
You may rightfully make a distinction between certain gases and their application, say medical oxygen and industrial oxygen. There is distinction to be made, but if that is of interest for the diver who mixes something in his shed is debatable. The medical O2 would surely be preferable, but thousands of people use industrial O2 for the same purpose. I have worked in countries where there is not even a distinction being made. This is not ideal, but tradeoffs are commonplace as places catch up with higher standards.
Similar, making a distinction between industrial Nitrox and breathable Nitrox is not wrong. Several industrial processes use O2 enriched air and that gas may well not conform to say BS EN 12021-2014 if we would talk about he European sector. Maybe Coltri doesn't meet the required standards in a certain sector to not make that industrial distinction. I do not know if this is the case.
Breathable air as per BS EN 12021-2014:
| Component | Concentration at 1013 mbar and 20 °C |
| Oxygen | (21 ± 1) % |
| Carbon dioxide | ≤ 500 ml/m³ (ppm) |
| Carbon monoxide | ≤ 5 ml/m³ (ppm) |
| Oil | ≤ 0,5 mg/m³ |
Breathable composition of nitrogen depleted air and oxygen enriched air as per BS EN 12021-2014:
| Component | Concentration at 1013 mbar and 20 °C |
| Oxygen | (Stated ± 1,0) % |
| Carbon dioxide | ≤ 500 ml/m³ (ppm) |
| Carbon monoxide | ≤ 5 ml/m³ (ppm) |
| Oil | ≤ 0,1 mg/m³ |
The distinction between those two is the amount of acceptable oil level.
You are not wrong in pointing out the mentioning of
industrial in their manual. I believe that your statement may mislead people into thinking that their compressor is not suitable for mixing Nitrox, when in reality it is perfectly capable of doing so. If it then adheres to a certain standard with regards to gas purity is another question.
At some stage we are arguing over semantics. As so many things in diving, it is a matter of personal risk acceptance.
I would love for everyone to have a Bauer B-Membrane system, as that is state of the art equipment for dive centre use right now. But that doesn't mean that a cheaper, less sophisticated system can't be used while at the same time, accepting the shortcomings of that cheaper system.
.. now I'm safe!
