Re: Computer And No Console

Iain Smith wrote:
> > It's a large chunk of metal made to take 300 bar. When do you
> > hit *your* kit with sledgehammers?
>
> There are different types of loading. You can load something axially,
> rotationally (torque) or you can try to bend it (I forget the
technical term
> for this).
Shear.
Any shear applied to the transmitter would cause the first stage to
rotate. You'd need to *accidentally* clamp your first stage very hard
and *then* hit the transmitter - and you'd still need to use a LOT of
force.
(You could hit it in the same direction as the first connects to the
valve, and then you wouldn't need to clamp it first, but any object
doing that underwater would need to go through your head first, so at
that point it really doesn't matter whether your transmitter survives).

> Just because something is designed to take an axial load of 300
> bar, does not mean that it can necessarily take any other type of
load of
> that magnitude.
>
> I can say that with confidence, having managed to screw a hose in so
tightly
> that it sheared off (the first UKRS SETT dive). I've also had a
manifold
> bent, though I'm not sure how. I am, however, pretty sure that the
bending
> force applied was nothing like 300 bar. It's extremely easy to bend a
> manifold when assembling a twinset, if one is not careful about
keeping the
> tanks aligned. Again, considerably less than 300bar need be applied.
Have you managed to suceed in any such feat underwater?

>
> As for sledgehammers, consider a scenario that I have seen. a scuba
set is
> assembled on a boat, is untied from the side and an unfortunately
timed wave
> hits the boat. The set pitches forward, landing on it's regulator.
Now
> imagine that the impact was taken on the transmitter. Think it would
> survive?
Probably (although I'd certainly have to check the calibration - same
as any SPG taking such a bang).
I'd be less worried about the transmitter than I would be about the
first stage (which probably wouldn't survive the shearing force on the
DIN fitting)

> > There are different types of loading. You can load
> > something axially, rotationally (torque) or you can try to
> > bend it (I forget the technical term for this).
> Shear.

That could be it...

> Any shear applied to the transmitter would cause the first
> stage to rotate. You'd need to *accidentally* clamp your
> first stage very hard and *then* hit the transmitter - and
> you'd still need to use a LOT of force.

Not necessarily. If you drive a car into a stationery car (even if it's in
neutral with the brakes off), you're still going to bend things even though
the other vehicle is free to move. Large impacts are going to bend things.

> (You could hit it in the same direction as the first connects
> to the valve, and then you wouldn't need to clamp it first,
> but any object doing that underwater would need to go through
> your head first, so at that point it really doesn't matter
> whether your transmitter survives).

> > Just because something is designed to take an axial load of
> > 300 bar, does not mean that it can necessarily take any
> > other type of load of that magnitude.
> >
> > I can say that with confidence, having managed to screw a
> > hose in so tightly that it sheared off (the first UKRS SETT
> > dive). I've also had a manifold bent, though I'm not sure
> > how. I am, however, pretty sure that the bending
> > force applied was nothing like 300 bar. It's extremely easy
> > to bend a manifold when assembling a twinset, if one is not
> > careful about keeping the tanks aligned.

> Have you managed to suceed in any such feat underwater?

No, but tore the hose off immediately before a dive and noticed the damage
to the manifold at a similar time. The diving environment includes more than
just the underwater bit.

> I'd be less worried about the transmitter than I would be
> about the first stage (which probably wouldn't survive the
> shearing force on the DIN fitting)

Actually, it did. The fitting took 18L of cylinders hitting the first
stage...which I admit to being somewhat surprised about. I think that
fitting is still on one of my Mares regs.

Iain