UV light to highlight contamination for O2 cleaning?

[scubaalblake]

Has anyone had any success using the cheaper UV torches for checking for contamination when O2 cleaning?
I just bought a (supposedly) 365nm inpection torch from ebay.
Ebay UV Torch

It doesnt seem to show anything up?
I can get the '70s disco effect with no problem - ie a white cotton shirt will glow BUT if I point it at a rag I *know* is contaminated with engine oil nothing shows. I am doing this in a dark room.
If it doesnt highlight something so obviously contaminated I have little confidence that it will show traces of contamination on oxygen regulator parts.
Am I wasting my time here?
HAs anyone go good results with these things? It only cost me $12 so not fussed about the price - but just wnat to know if I am wasting my time.

 

[tmassey]

UV fluorescence is not at *all* a reliable method to detect hydrocarbons — especially in the world of synthetic lubricants. Some lights are more effective than others, and maybe a different light than yours would work better (you need a *bright*, well-filtered light), but *none* are anywhere near 100% reliable — because some contaminants simply do not fluoresce.

UV is a tool that can let you know something is dirty, but it *cannot* tell you if something is clean.

ETA: A quick Google finds this link: Not All Oil in Water Monitors Are Created Equal

Yes, they sell a system that competes with UV light; but the reasons they go through as to why UV is, by itself, insufficient is pretty clear. In short, not all hydrocarbon contaminants fluoresce.

 

[tmassey]

If you’re talking small parts (and you are), there are two common ways to detect hydrocarbons. First, before you take the parts out, look carefully at the surface of the rinse water at multiple angles. Do you see *any* oily sheen? They’re not clean. (Why don’t you take the parts out? So you don’t contaminate them as you remove them through the oily surface! ) Second, decant some of the rinse water into a small, sealed container. Shake it up hard. The bubbles formed should break almost instantly: certainly in a second or two. If they don’t, the rinse water is *not* just water.