21 Dec 95 15:52, Lee Bell wrote to Terry Howard:
 ->> One system I've often though would work (still don't know why
 ->> its not done) is a small 'backup' regulator (much like the 'spare
 ->> air' regulator setup) integrated into the body of a main regulator
 ->> 1st stage. This would give complete redundancy for all life support
 ->> equipment and could replace the users spare 'octopus' 2nd stage.
 LB> This would double the bulk of the first stage and the cost of service.
 LB> Since air would be coming through the same passage, a freeflow or
 LB> burst hose would still be a serious problem unless some mechanism
 LB> was included to allow one channel to be closed and the other
 LB> opened.  I'd be willing to bet there's a manfold out there
 LB> somewhere which would do this at the tank valve rather than the
 LB> regulator, an altogether more economical and simple arrangement.  I
 LB> know this system is available for doubles.
Sherwood made a benjamin valve for doubles with separate outlets and on-off 
knobs, allowing true redundancy for those diving in overhead environments. 
They also made a "slingshot" valve for use on a single tank that would give 
the same redundancy.
Jay
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