2 quick newbie questions re "rolloff" and innertubes

[dlwalke]

1) what's "rolloff", I've had the impression from the posts in which I've read this that it refers to your cylinder knob rolling all the way back so hat you are no longer getting air, but am not sure as I can't envision how it would happen given the number of complete turns that would be required to do this (at least with the cylinders I've rented).

2) I'm starting to attach things to my BC and have read comments about people using innertube to do this, but I can't quite envision it. Actually I can envision a few options but not sure which if any are correct. Is the idea to slide an innertube segment along the belt or strap such that the belt or strap is inside the inner tubes innards - and then objects such as a flashlight can be squeezed in there also if they and the tube are of the appropriate diameter?

Thanks,
Dave

 

[kcanty]

Rolloff in general refers to the left post on
a set of doubles contacting an overhead
and being rotated off. Due to the standard
open-counter clockwise // close-clockwise
setup on scuba valves the right hand post
will only roll on.

It is not only possible but probable. Also
some manifolds have as little as 2 complete
turns from stop to stop in order to facilitate
rapid shutdown/isolation.

As for the innertube think of a bike innertube
and take a cross-section of it thus making
a small stretchable loop. One reason to use it
rather than bungee is that it lays flat and won't
move up or down the held down object ( such as
a light ) as easily.

Kell

 

[roakey]

Plus I'd like to add that the single cylinders you're diving with now have what would be called a "right post" in doubles terminology, so you don't have to worry about a roll off.

If you were to brush an overhead the valve would roll more open if possible.

Roak