Re: [PSUBS-MAILIST] air pressure

Hi Pierre,

the air inside a normal size one- or two- man 1at sub reach about
1-2 hours. In Sgt.Peppers 40 minutes. After this time you have to
surface to refresh the air - or you will get headeges and later died.
For this reason and to fullfill the class requirements the most
sub have a L.S.S. = Live support system.

The simplest one is :
A CO2 scrubber with a electric
blower and a bottle with oxygen (not air) and a barometer.
If the barometer goes down because of the conversion
from O2 to Co2 by your body - and the CO2 filtered out by the scrubber
you have to open the oxygen bottle by hand until the barometer has
again the original 1atm.

The better one have a automatic vale to do this job.

A little saftey feature will be a snorckel near the tower so you can use
outside air directly to your mouth - and drive the boat also on the
surface at rough sea with closed hatch - important at boats without a
tower.

A full size L.S.S like in the Euronaut will have :
- Two groups of oxygen bottles, storage place outside the hull for
saftey reason (imagine whats going on if a inside bottle with oxygen has
an leak..)
- One scrubber with scrubber cartridges and a storage locker with supply
cartridge to extent the run time according to the class rules.
- one barometer, one O2 indicator, one CO2 indicator, one H2 indicator
- 12 V emergency battery , 24 Volt emergency battery
- A suba pressure air line with conection points in all compartments
with face mask - for air suplly in case of fire.
- A second system in the diverchamber

The idear you have with storage air and a constant flow like the
most onshore decompression chambers have is not possible because :
- you need a compressor to get the air flow out of the submarine
if the submarine is dived, and in greater deeps the compressor needs to
much power.
- The storage of air-bottles will get really big..

For dry ambient subs the air flow methods is more usefull because
they divedeep is not so much and there is no compressor nessesary
because of the all the time ambient compartment.
Inlet and outlet should by away from together. And a
soundsilencer on the in- and outlet vales makes possible sence.

best regards - Carsten WWW.Euronaut.org