Re: 300 bar ??

[Albert Long <subview@mediaone.net>]

Your right ! Thanks...

A. Long

protek@shreve.net wrote:

>     Check valves in the hull require a certain forward pressure to actuate.
>  The problem here is that this pressure added to the pressure differential
> through the valve with air flowing may be several PSI.  Multiply this
> pressure by the hatch area and it can lift the hatch anyway.  Like I said,
> high pressure power piping inside the hull has risks.  I have valves for
> quick shut off.  But there are still risks.  Another approach is a hatch
> mechanism that can burp the air.  In other words, if the hatch given inside
> pressure, opens slightly against the seal to release the pressure this can
> be a check valve in itself.  Problem here is if the hatch seal is not
> forced down against the seat you may have leaking till you are 5 or 10 feet
> deep.  I have a hatch system that will allow this but I usually tighten the
> hatch to the tight position.
>
> Gary Boucher
>
> At 09:24 PM 10/26/98 -0800, you wrote:
> >How about a "check valve" that would blow off any pressure reached over
> ambient ?
> >If  something did go wrong and pressure did bleed out into your pressure
> hull, the
> >pressure would reach ambient then excess would blow out your sub via the
> valve...
> >Granted, if it was a large volume at once It could be slightly damaging to
> one's
> >ears, but at lease it would not blow your hatch off !!!
> >
> >A. Long
> >
> >protek@shreve.net wrote:
> >
> >> Bjoern,
> >>     Seems that I have been putting out a lot of "air" lately so why stop
> >> now.  Most small sub designers would rather put high pressure tanks outside
> >> the hull where any malfunction would just release air into the water and
> >> not the inside of the hull.  I chose to place two scuba tanks inside with
> >> me with scuba first stage regulators.  These regulators greatly reduce the
> >> pressure.  Where I sit I can reach both main valves on these tanks as they
> >> are in front on either side.  These regulators do not often fail with the
> >> release of high pressure air into the system but they could.  At least I
> >> can reach the tanks.  Once I connected the system air connection
> >> accidentally to the high pressure side of a regulator during development of
> >> my boat.  It blew a 300PSI flexable line like it was a balloon poping.  I
> >> was in the sub.  Could not hear to good for a while!  If you direct high
> >> pressure air directly into a ballast tank full of water there is no
> >> compression of the water so the tank pressure can spike to the level of the
> >> supply.  I have considered a restriction at the tank itself to prevent
> >> surges with full tanks.  My tanks are around 1/4 inch thick.  There are
> >> easy ways to test the ballast tank pressure surges without installing
> >> ballast tank pressure monitoring thru-hull.
> >>     In short, this is what I did.  There are risks due to high pressure air
> >> inside the sub that should not be underestimated.  Far better and safer to
> >> place high pressure air outside.  One other factor; all scuba tanks have
> >> rupture disks that are designed to give way to protect the tank from
> >> exploding if overheated when the pressure rises.  This is a violent release
> >> of air!  If this ever happened inside the sub the occupant would probably
> >> not make it.  I do not fill my tanks to the max allowable.  Also the inside
> >> of a sub can reach high temps when transporting it.  They could explode the
> >> sub itself with the hatch bolted or at least blow the hatch open.  Lots of
> >> things to consider here.  Small leaks in high or low pressure air can cause
> >> the inside air pressure to increase to the point the hatch blows open.
> >> Richard Hess told of a case where the sub sunk due to blowing the hatch
> >> open.  You can not detect slow changes in air pressure.  Need a barometer!
> >>
> >> Gary Boucher
> >>
> >> At 12:08 PM 10/26/98 +-100, you wrote:
> >> >Can somebody tell me something about
> >> >working-air-pressure inside my 1 atmosphere psub.
> >> >I want to reduce the 300 bar from four tanks with some scuba
> >> 1.stage-regulators connected to a tank that holds the working air.
> >> >
> >> >Or do I have to use 300 bar directly, whit tubes and valves that handles
> >> the pressure ? What about the risk of exploading the outside tanks when
> >> ballast blowing, or what about high-pressure tube-exploading inside the
> hull ?
> >> >
> >> >Regards,
> >> >Bjoern Engh (Norway)
> >> >
> >> >
> >
> >
> >
> >