OP
swamp diver
Contributor
Maybe they took it from the Simple Green Website which give a 1:500 dilution for Oxygen cleaning.
Simple Green | Industrial
Thanks very much for that link.
So that is the source of the 1:500 dilution rate and PSI in their OCCT course is referencing this for O2 valve cleaning.
It would be interesting to know the rationale behind such a high dilution rate other than a very low likelihood of leaving any residue behind, but you really have to wonder about its cleaning potential with only 2 ml in a litre of water?