SDI still teaches OW using tables
This is where you were wrong.
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SDI still teaches OW using tables
... I do have a fair bit of experience of vehicle exhaust analysis, including set up after LPG conversion. Also experience of welding gas analysis and purge / vacuum chamber gas analysis. Gas analysers are not that reliable, can be affected by unanticipated factors and give variable results. Gas contamination although uncommon is more frequent than might be expected. I have known gases contaminated with oil and rust particles and significant percentages of wrong gases in cylinders. Carbon Monoxide and Oxygen sensors in analysers are often far from 100% accurate.
The reference Gas is compressed air, 21%O2.I am qualified to audit company quality assurance systems to BS5750 / ISO 9001 and have done quite a bit of this in the course of my previous employment. I point out that my experience is with industrial gases and automotive exhaust gases not diving gases. Any equipment is only as good as the people using it and the system that is in place for managing its use and maintaining it. It is far better to have nitrox analysers even if they occasionally give incorrect readings or are a few percent out. If a gas analyser is properly maintained and checked for accuracy (using a calibrating gas) before and after use it is highly unlikely it will give a false reading. However in an analyser is only used infrequently and left in a toolbox or typical workshop conditions and not tested immediately before and after use you should be much more wary of its output. I suppose when checking nitrox you know what the composition should be and therefore if you are checking a number of cylinders any incorrect blend should show up pretty clearly.
I am qualified to audit company quality assurance systems to BS5750 / ISO 9001 and have done quite a bit of this in the course of my previous employment. I point out that my experience is with industrial gases and automotive exhaust gases not diving gases. Any equipment is only as good as the people using it and the system that is in place for managing its use and maintaining it. It is far better to have nitrox analysers even if they occasionally give incorrect readings or are a few percent out. If a gas analyser is properly maintained and checked for accuracy (using a calibrating gas) before and after use it is highly unlikely it will give a false reading. However in an analyser is only used infrequently and left in a toolbox or typical workshop conditions and not tested immediately before and after use you should be much more wary of its output. I suppose when checking nitrox you know what the composition should be and therefore if you are checking a number of cylinders any incorrect blend should show up pretty clearly.