Re: [PSUBS-MAILIST] re: 1atm subs

["Karl & Shirin Fuller" <fullerk@voyager.co.nz>]

----- Original Message -----
From: Paul Suds <paul_suds@hotmail.com>
To: <personal_submersibles@psubs.org>
Sent: 18 March 2000 10:38
Subject: Re: [PSUBS-MAILIST] re: 1atm subs


> You wrote:
> a
> blowoff valve will not work if the pressure outside is greater
> than inside
> so do you use a air pump to pump it out (more calculations what
> size pump)
> Troy
>
> Troy, when designing my sub (I have extremely limited personnel space), I
> had to take this into consideration. I thought about a small vacuum pump,
> but considering I'd only be down an hour, and the pressure from O2 and -
CO2
> scrubber, would only build up to an additional 7 psi after 6 hrs (5 hr
> reserve). This is assuming staying below 15 ft for the entire hr (not
> likely, but possible). Upon ascending, a check valve (pressure relief
valve)
> would open and start bleeding off air. I'm looking at a pilot operated
SRV,
> which is actually safer, but more complex. Anyway, it depends on your
> approach. If you want to pump it out, you still have to have an opening
and
> a check valve. The pump size can be extremely small similar to one of
those
> emergency tire inflators for your car.
> Suds
Troy and Suds,
If it was an Autonomous sub, I have thought that it woudl be possible to set
it up so that, if for any reason you had an over pressure in the sub, you
could reduce it ( if you had a battery powered compressor ) by starting the
compressor and pumping the air into the resivoir as you would on the
surface.
Any comments ?
Karl.