solocavediver

OK folks so let's express this mathematically (excuse me I'm a mathmo). What I call an "unbalanced" regulator and Joe calls an "uncompensated" regulator produces a roughly constant second stage pressure of 14 bar. So, below 130m nothing will flow out of it - not usually a problem with the recreational divers who buy this kind of reg, since they stop somewhere around 40m. A balanced one produces a variable pressure, if the ambient pressure is X you get an output pressure of X+14, to suit equipment like 2nd stage o/c regs which like a constant pressure difference. But I guess the trick with CMF valves is that you only really get constant mass flow if the intermediate pressure is enough for the physics of it to give that constant mass effect, which if I remember rightly is when the IP is around twice ambient. So you'd need to modify the 1st stage so that at ambient pressure X it produced an output of (maybe) 2X+14. Obviously no o/c reg is made that way because it would freeflow once the IP got significantly above the value X+14 which 2nd stages are designed for (that little spring inside your 2nd stage valve would be pushed back, resulting in a freeflow). If Janwillem has done such an adaptation himself I'd love to see the details of this little wonder of DIY engineering..... But maybe it's just easier to adjust an uncompensated reg to produce a constant 50 bar (e.g. stronger spring inside the 1st stage). That gives at least 2X until you get down to 240m deep. Not many of use dive below 240.

Cheers,

Charles.