Re: [PSUBS-MAILIST] Dry-Ambient pressure equalization

[Ian Roxborough <irox@ix.netcom.com>]

On Wed, 12 Nov 2003 07:51:05 -0500
pierre&marie <poulin.carrier@videotron.ca> wrote:

>
> #3: Natural equalization: This method is very simple. Drill
> a hole at the bottom of the sub and plug a hole from that hole
> under the sub. I recommend about 2 feet long. The hose is outside.
> Then, you put a manual valve inside the sub on the hole. After
> the valve, you put a clear hose all the way up inside the sub
> and make it loop all the way down the sub. You then need a
> constant air supply. Et voila! when you closed the hatch, open
> the valve and let air comming inside the sub. When you dive,
> watch the clear hose. If water come up the hose, slow down the
> dive or augment the air intake. The 2 feet hose outside the sub
> will give you a 1 psi positive pressure inside the sub.

Hi Pierre,

wouldn't it be possible, using a similar method as above, to
have a float in the tube with a lever attached.  When the water
rises, the float rises. If the lever was attached a valve, when
the float rises above a certain level it would open a valve
letting more gas into the cabin.  Once enough gas has been added
to make the water level in the tube and the float go down below
it's 'add gas' level, the float will pull the lever down again,
closing the gas valve.  If the length of the arm was adjustable
it should be pretty easy to fine tune it.

Ian.