Re: [PSUBS-MAILIST] Ambient Pressure (No Subject)

[David Buchner <buchner@wcta.net>]

On Monday, Mar 24, 2003, at 19:40 US/Central, Pierre Poulin wrote:

> I only have a hole at the bottom of the sub with a ball valve and a 
> piece of clear tubing that goes to the top and down to the bottom of 
> the sub. The end of the hose is open­. I also have another ball valve 
> that provide compressed air from a cylinder into the hull. So the 
> principle is very simple. If there is not enough air comming in the 
> sub to equalize the pressure, water will want to go into the sub by 
> the clear hose. I will see it gooing up and I will open the compressed 
> air valve to augment pressure inside the hull. If there is to much 
> compressed air comming in the hull, I don't care because the excess 
> will go out by the hose. The end of the hose is at the bottom of the 
> sub to expulse water that might comme into the sub and to expulse co2 
> which is heavyer that o2.

That's the sort of simple way I might have come up with. But (and, 
apologies if you've described this more in the past and I forgot) -- 
does this arrangement respond fast enough during descent and ascent? I 
guess: how big is that clear hose? What if you're rummaging in the 
cooler behind you for another beer, and your shirt sleeve catches on 
the dive plane stick, and you start ascending rapidly -- is there a 
danger of higher pressure building up inside because you're rising 
faster than the air gets out through your tube?

- - -

David
buchner@wcta.net
Osage, MN, USA
http://customer.wcta.net/buchner