Re: [PSUBS-MAILIST] L.S.S.-Life Support System

[MerlinSub@t-online.de (Carsten Standfuss)]

Sean T. Stevenson schrieb:
> 
> Carsten, how is airflow managed in your sub?  Did you model the airflow, just
> as you would when designing ventilation for a building?  Does your scrubber
> intake only from an area near the scrubber, or is there ductwork for inflow
> and outflow to ensure consistent CO2 concentration everywhere in the interior
> space?

Hi Sean, at the moment there are 4 filters in the boat, two are in the
WC-room 
and two are in the diver-chamber. There is no airduct system. Will
measure Po2 
and PCO2, CO and He and hydrogen.  But the filters are vertical pipes of
about 
one meter (3 foot) high. The cabin air has more temperation on the top
area of 
the filters than on the bottom part - so there should be an airflow. 

> You also mentioned the temperature dependence of cabin pressure.  I wonder
> also about the moisture content.  Scrubbers work most effectively when the
> air to be scrubbed is dry - do you use a dehumidifier?  How much heat, and
> how much moisture is expelled per person per hour?  Is this insignificant
> compared to heat loss to the outside?

Thats not really true - a scrubber needs some moisture to work. 
A scrubber in a divers rebreather has to workwith a lot of moisture of
your breathing 
and works fine. A scrubber in comlete dry air will maybe not work ?

I calculate with 150 Watt heat at one person for one hour. And about 0,1
Liter 
breathing water in 1-2 hours. Anybody better figures ? 

The subs steelwalls are insulate on the inside - but only over the floor
plating. The steel under the floorplates are just paint.  So moisture
will convert into water on this parts because of condensation of the
walls in the bilge and collect on the bottom - and than pumped out by a
high pressure seawater pump.

With the boat on the surface and diesel running and battery on charge
the airflow goes from the open sail-hatch to cabin from there to the
battery compartment - from there to the engineroom and here into the
diesel engine - which like to eat any hydrogen vapor, save maybe diesel
fuel, maybe not - but remove any fume from the cabin and battery
compartment.. ;-)  

The sensors for hydrogen will be on the ceiling. 

regards Carsten  

> -Sean
> 
> On December 14, 2004 12:40, Carsten Standfuss wrote:
> > And this loss of pressure can open an automatic barometric oxygen-vale..
> > ..very simple control. Self-leveling. But not undepentable of the
> > temperation of the cabin air.
> >
> > Better is also to meassure the PO2 pressure in the cabin. And maybe the
> > PCo2.
> >
> > I have a question for all - in the "Seehund" world war two two man
> > submarines they use the oxygen-flow from the oxygen pressure bottle via
> > a injector nozzel (venturi nozzel with side entrance) to flow the cabin
> > air (in mixture with the oxygen) to pass the scrubber. No fan. My
> > impression is that this can not work because the oxygen flow is to low -
> > but obviously some of the boats stay two days underwater.. Any idears
> > how to calculate or explain how it works ?
> >
> > regards Carsten
> 
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