Air from surface down to 1.5m

[CS]

A bit techy but how much effort would it be to breath air supplied by
a hose from surface ie divers's lungs would have to overcome the water
pressure. Looking at max 1.5m - so 0.15 bar overpressure from the
water.
Eg using a snorkel with a 1 inch ID hose to surface.
As long as the residual CO2 is cleared out of the hose on each breath,
that should not be a problem - and the Royal Navy used to use a Patt
5665 breathing apparatus for firefighting which was a mask on a 50ft
air hose!

[Invalid]

In message
<200d5810-0fed-40d7...@w1g2000yqm.googlegroups.com>, CS
<crms...@gmail.com> writes

A quick Google for "maximum snorkel length" suggests anything over 40
cm starts to get dangerous. You can apparently rupture the lungs trying
to suck against the pressure differential.

The Patt was designed for use with no (significant) pressure
differential between the lungs and the open end.

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Invalid