2airishuman
Contributor
Manifolded twins have long been the gold standard for safety for technical dives.
I wonder how much safety benefit the isolator valve actually provides. Have there been any accidents or incidents where the ability (or lack of it) to close the isolator valve made a difference in the outcome of the dive? Have there been any accidents or incidents where a sensibly maintained single-cylinder configuration suffered an abrupt loss of gas below the valve after the dive was started?
I also wonder about the advantage of the crossbar itself. Sidemount diving has become accepted, and sidemount configurations don't have a connection between cylinders comparable to a crossbar. Do sidemount divers plan their gas based on loss of the most critical cylinder at the most critical point? Does sidemount provide a material advantage in safety over independent backmount doubles? Enough so that backmount doubles really do require a crossbar while sidemount does not?
I wonder how much safety benefit the isolator valve actually provides. Have there been any accidents or incidents where the ability (or lack of it) to close the isolator valve made a difference in the outcome of the dive? Have there been any accidents or incidents where a sensibly maintained single-cylinder configuration suffered an abrupt loss of gas below the valve after the dive was started?
I also wonder about the advantage of the crossbar itself. Sidemount diving has become accepted, and sidemount configurations don't have a connection between cylinders comparable to a crossbar. Do sidemount divers plan their gas based on loss of the most critical cylinder at the most critical point? Does sidemount provide a material advantage in safety over independent backmount doubles? Enough so that backmount doubles really do require a crossbar while sidemount does not?