I can't say none because that is finite. None reported, how's that? Would be interested in these cases of combustion. Because as you well know, anything that happens in the scuba community spreads like wild fire, no pun intended and everybody knows about it before they even get to the hospital. Show me your facts and studies and cases before we can discuss this. You can run computer models day and night to achieve the desired results. But "real world" states different.
Also in PADI's "Enriched Air Diver" manual on page 9 Item #1 it states, and I quote:
"Most scuba regulators, BCDs, SPGs an alternate air sources may be use with enriched air blends that have up to 40% oxygen, after making any modifications required by the manufacturer. Based on the standards and field experierence of NOAA, the U.S.Navy, OSHA and others, some in the dive community believe that standard air equipment can be used with blends up to 40% oxygen without modification. Though this practice appears to have anb excellent field record, you should still follow manufacturer recommendations."
I am not trying to blast you on this, but to say that anything other than air, and that is basically what they are saying, needs to be O2 cleaned is a little far fetched.
Another thing, if you are gonna have to clean your regs, why wouldn't you have to clean your BC, drysuit, SPG or anything else that comes in contact with +25% nitrox. This theory just doesn't wash IMHO. If it was that big of a danger, I damn sure wouldn't want a fire in my drysuit with me in it.