Re: Pressure regulation

["Alan D. Secor" <secor@btv.ibm.com>]

How are you going to handle CO2 buildup?  Also, to vent normal air into
the cabin, trying to maintain a 21% O2 environment, the net pressure 
inside
the cabin will increase since you are also adding nitrogen which is not
metabolized.  

Al

> 
> As for air supply- since my sub will be designed for relatively shallow
> depths less than 30m I thought I would use a low voltage air compresser
> and a metering valve to expell air at a constant rate and a SCUBA type
> compressed air supply fed through a diaphragm valve to maintain a stable
> air pressure.
> 
>  Since most diaphragm valves vent the "back side" to the atmosphere, the
> vent will have to be fed to an airtight chamber large enough to allow
> normal movement of the diaphragm. There could be some sort of volume
> adjustment on this chamber to "dial in" barometric pressure.
> 
>  My sub will be very small and I have access to a SCUBA compresser to
> refill my air tanks so it will be easier for me to use compressed air
> than an oxygen supply and CO2 scrubber. With dropable ballast and maybe
> a spare-air for emergency escape I think I can safely design a fresh air
> system based on a two or three hour limit instead of a seventy two hour
> supply.
> 
>  If anyone knows of a reason this type of system won't work or a way to
> make it better I welome feed-back, It will be a few years before I start
> construction so I may change my mind on a lot of things by then.
> 
>  Daniel.
> 

--
Alan D. Secor
e-mail: secor@btv.ibm.com