UV Helmet Damage?

[dbb]

So John's thread got me thinking about my helmet's viability again. What do people know about UV damage to hard shell plastic helmets? (I have an ecrin roc)

The reason I ask is because my pack faded to about 40% of it's original color in alaska, and my helmet usualy sat right next to it. (or on my head )The helmet is also about 5 years old (?).

I know of the adage "When in doubt, retire it" but what are other people's opinions? Any ideas on replacements? Anyone used the HB Olympus?

[jon]

I looked on the Petzl website and they said the materials were good for 5 years, then should be replaced. I'd didn't say whether the material is polypropylene or polystyrene, which I think makes a difference. Usually when a company gives an "expiration date" figure like five years that is worst case. We use pretty powerful UV lights to sterilize our biological safety hoods at my work and it takes quite a long time for them to destroy any plastic products we may leave in them. Usually the plastic becomes very brittle and then fails. That said I think the other materials in a helmet would wear out before the plastic shell become to brittle to use. Might be worth asking Petzl about though I could very well be wrong. Good thinking Dave.

[AJ]

UV affects plastic in almost all conditions. Yes, there are some areas that have higher exposure thresholds (think very sunny areas) but manufacturer's of plastics generally give conservative ratings. Plastic does not age (deteriorate) on a linear scale so manufacturer's typically give conservative estimates of the service life. Plastic also deteriorates as a function of temperature (on both ends of the scale). Very hot plastic blasted by high UV will break down fast. Also, extremely cold plastic blasted by high UV will break down quick. Cool plastic with no UV exposure not lose much strength over a long time.

I have worked a lot with the polyethylene pipe industry and know that manufacturer's usually give recommended shelf life of plastic stored (outdoors or indoors) of between 3 to 4 years for medium density and around 5 years for high density (HDPE plastic pipe has more carbon black which is the active UV inhibitor). Those ratings are based on testing done in Yuma, AZ in direct exposure and they are 1/2 of the time it took to see a 50% reduction in strength. Oxidation of the outer skin is often associated with extreme UV exposure but it is not a very accurate way to estimate remaining strength. That said, if you see significant oxidation you should be concerned about the plastic.

Climbing helmets can be made from a variety of plastics so it would be difficult to generalize. Buying a new helmet every 5 years seems reasonable.

[lizard_brain]

I have a plain ol' Edelrid, and when I bought it the person that sold it to me told me I should replace it after at least five years. But I did buy it at REI, and I've often found that their salespeople don't know what the fuck they're talking about.