Mailing List Archive Mailing List Archive
Chuck Boone <chkboone@ao*.co*> writes: > Anthony, > > This was apparently simply a stuck inflator valve coupled with ice in the dump > valves. Could have happened to any poorly maintained and/or operated > buoyancy device. Not the fault of the bondage wings ! I didn't say it was; in fact, I said it probably made the same sound bursting as a single would, for whatever that's worth. The main point I was trying to make was about common-mode failure analysis. A simple-minded concept of redundancy is that if something is 99% reliable, having a redundant one gives you 99.99% reliability. This only counts if the two are truly independent. If one blowing up takes down the other (see the O2 tanks in the Apollo 13 SM) or if a common external factor can take down both systems together, then your reliability drops accordingly. > The only way I can see cold conditions causing a failed dump valve is if he > let ice form on them on the surface and it held them shut . Since the > report says the diver was unhurt the incident probably happened near the start > of the dive before the ice could melt in the water. Diver Error ! ! ! That's a secondary problem; the main problem was the runaway inflator. Probable analysis: water inside the wings from a previous dive would have collected in the end of the hose and in the overpressure and frozen there. > The bondage wings are designed for a fast dump in any position anywhere in the > known universe because there is always positive pressure on the contained gas. .... > So, what we have here is a diver who now fears the consequences of a stuck > inflator valve refusing to buy the only set of wings designed specifically to > accommodate that exact situation if used properly because he blames the wings > for what appears from the report to be his own failing. That same bondage prevents oral inflation. It's a bit specious to say these wings are designed specifically to accomodate an obscure failure mode, especially when the first line of defense is an inflator that doesn't freeflow, second line is a hose kink, disconnected inflator, or tank valve closure to stop the incoming pressure, and third is at least one deflator that works. Positive pressure to deflate isn't going to help if there aren't any deflators in business, and a few bits of bungee meanwhile aren't going to slow down your interstage pressure for long enough to make a difference. -- Anthony DeBoer <adb@on*.ca*> -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]