Re: Air Use Calculations

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

Hi Chris, 

I use this way in Sgt.Peppers during test work in my garage. 
My girlfriend was outside with a clock and I shut the hutch. 
After 40 Minutes the headedges started because of the CO2 level which 
gives earlier a problem (and is a good indicator) than loss of O2. 

The internal displacement of the cabin is 480 liter minus 80 liters
of my body = 400 Liter, so you can say 400/40 = 
estimate 10 Liter free volume of the cabin is 1 minutes livetime. 
I use this sometimes for short test dives to save the 02 and the
absorber of the rebrather system - but never longer than 20 Minutes
and ever with the rebrather ready as second security system. 

One problem is to clean the cabin after using this way. My cabin is so 
small that I go in / go out 3 times a the displacment of my body remove
parts of the dirty air. But a bigger ventilator with a mobile pipe
to the hutch will be work better (I think). 

If you have no rebreather system in your boat and your boat catch a net
on the bottom you need a very big flooding vale to flood your boat
and get quick way out. 

Its a cheap way to dive with the internal air - but you need a 
rebreather system to give you the time to make some repairs underwater,
or to leave the boat, or give your friends the time to look for a crane,
lifting ballone, your boat..

The both people which died in the two person sub Tigerhai in the 60ies
died because of the C02 level after some hours on the bottom in the
damaged boat. The died a very hard way - the police found
destroyed/damaged finger nails on the dead bodys and scratches all over
inside the sub, the shoes of the unlucky persons also damaged ...

The normal security time for a certified sub is 72 hour. 

Be happy, Carsten 


Chris Nugent schrieb:
> 
>      Hey all,
> 
>      There having been a lot of discussion about
> rebreathers and other various environmental systems
> lately, I came up with a question.
>      The design of my sub being as economical and
> simple as possible, I have only allowed for a
> submerged endurance of say one or two hours.  Mostly
> the idea is to avoid building a scrubber and just use
> cabin air.  As long as I have a good monitoring system
> in place, I plan to come up every hour or so and just
> ventilate the cabin w/fresh air.  Opinions on this?
>      So my question is, does anyone know where to find
> how to calculate volume of breathable air used by the
> human body per minute?  Can one extrapolate an
> estimate of submerged endurance  based on the volume
> of air in the cabin versus volume of air used by the
> human body?  Let me know what you guys think.
> 
>                                   Thanks,
> 
>                                     Chris
> 
>  P.S.  Thanks to all who sounded off on the "Tour of
> The Boat"  thing....nice to meet ya
> 
> =====
> "Noisy outside, empty inside." - Confucius
> __________________________________________________
> Do You Yahoo!?
> Bid and sell for free at http://auctions.yahoo.com