On Friday, February 16, 2001 12:20 PM, John Nitrox wrote:

> >What's the difference between a 'K' and a 'J' valve?  And where did the
> >terms come from? :-)

(snip)

>I don't think that the names 'J'
> and 'K' have anything to do with shapes as is popularly thought but rather
> with their placement in the catalogue; the 'J' valve preceding the 'K'
> valve.

G'Day, Mate!  The U.S. Divers catalogue (1954 and earlier) listed equipment
alphabetically.  Valves with a reserve, (a pull rod that, when breathing
became difficult, could be pulled down and that would release about 300 psi
of gas for an ascent), were "J" items. (J1 - Standard tank valve with air
reserve set at 300 psi: J2 - To valve and connect 2 cylinders with air
reserve set at 500 psi: J3 - To valve and connect 3 cylinders with air
reserve set at 700 psi.)  The cost of a J1 was US$30.00!  :-)

The item under "K", was a, "junior tank valve without reserve".  Cost
US$8.95! :-)

Bear in mind that in those times some divers dived without instruments other
than - perhaps - a watch.  In that regard the "J" valve was considered to be
superior to the "K" type valve.  It did, of course, have set backs!  If the
diver neglected to set the lever in the "off" position prior to the dive -
or if, for some reason, it became knocked "on" during the dive - then, when
breathing became difficult and the diver attempted to operate the reserve,
nothing would happen!  :-)

Strike