A friend once told me she thought u/w photographers might make good partner-marriage material. "After all", she said, ripping off the wonderful line from Joan Rivers, "you're already used to spending money on neat non-essentials, you exhibit patience and a willingness to delay gratification, and you've experienced lots of pain."
As many here already know, I experienced the pain of my second flood in a lifetime a few weeks ago. The problem was the o-ring on a 50 mm port extension ring, which was not seated properly because it was the wrong size.
This doesn't concern anyone who has purchased a Subal housing and ports new recently or is about to do so, but as anyone who has acquired a motley collection of newer and older Subal ports and extension rings is probably already aware, Subal changed their port-o-ring specification a few years ago.
The groove in all the newer ports and extension rings is configured for a 3 mm o-ring (Part ORPTB3) while older ports and rings require a 2.6 mm O-ring (ORPTBJ). If you compare the two o-rings side by side, it's fairly easy to distinguish them, but looking at a port or extension ring, it can be difficult to tell whether it takes the old or new style o-ring. Except for the width of the o-ring groove, older and new models of ports and rings manufactured before and after the changeover are almost indistinguishable. There is no special mark or instructions on the new ports and rings telling you which kind of o-ring to use.
I knew that my older 105 mm flatport took the old thinner o-ring, while my newer big dome port took the new, thicker ring, as did the 50 mm extension ring I normally use with the domeport when shooting with the 12-24 or 17-35 zooms. I've done a pretty good job of keeping the two different size o-rings straight over the years, but what I didn't realize is that my second 50 mm extension ring was older, and takes the older ring. On this occasion, I either mixed up the extension rings, or else I may have pulled the o-ring off the 105 mm macro port (thin style) and put it on the extension ring (new style) in a hurry. I'm not sure which, and the shitty lighting that in my room at the Paradise at Tulamben didn't help, but that's more or less how I ended up having a flood. Similar problems might have been the cause of John Bantin's recent Subal FS2 flood as well.
NOW (too late), I do know how to tell for sure which o-ring a port takes. The trick is to look at the thickness of the flange next to the o-ring groove. Subal has made this flange thinner on the newer ports and rings to allow room for the wider o-ring groove. If you compare two ports, one taking the old style o-ring and the other the new, the difference is unmistakeable. (See diagram, which I requested from Subal so that I could sort out once and for all which size o-rings and ports/rings are which.) I have added pointers to the flanges I'm talking about in their diagram so you can see what I mean.)
Frogfish
So I would advise to all Subal users with old ports let them service and adapted to the new O-rings so you would not flood your housing because of this.
