There's a closer picture on one of the ebay auctions. The key features seem to be fins on the body and enlarged ambient ports though there are probably some beefed up TIBs etc inside too.
The freezing effect in cold water doesn't come from the cold water - if it was cold enough to freeze, it would be ice. It comes from the cold created inside the reg by the expansion of gases. Normally the surrounding water is warm enough to dissipate the cold, however, as the surrounding water gets colder, it's ability to do so is reduced, so at a certain point the reg gets cold enough to freeze the water inside the ambient or spring chamber.
That being the case, there are two ways to try and keep the spring chamber from freezing. The traditional way is fill it with something that won't freeze and will keep the water out, so there isn't anything to freeze. However one can also try to speed the transfer of cold from the chamber to the surrounding water to make up for the lower transfer rate, and make sure the water doesn't stay inside long enough to freeze up.
This is the approach Poseidon has taken on the new Xstream, surrounding the mainspring with openings so that there's a constant flow of water though the spring chamber. Looking at the picture, it appears likely that SP is taking this approach too, by adding cooling fins to the reg body and hogging out the ambient ports to increase water flow through the spring chamber.
If that is what they are doing, and it works, it'll be great, because it's simple and clean and will solve one the balance piston's major weaknesses. However, SP has made several previous attempts to come up with a dry anti-freeze system, and the Xstream is still too new to say for sure how successful it is from a cold water point of view. So if I owned a MK25 and was diving cold water I think I'd stick with the silicone for now.
Tekkie once bubbled...
Hey,
Does anyone know anything about the new Scubapro Anti-Freeze (AF) system for first stages? I searched the net, but everything was in German. Do you know if it can be added on to an existing Mk25 regulator? And if so how much does it cost or is it not avalable in the US yet? Also what is it's recomended temp limit?
Thankz
Tekkie
