Re: [PSUBS-MAILIST] Using a commercially available hatch as an emergency escape hatch.

[Dan h <machine@epix.net>]

If you check PVHO regulations, acrylic is the only choice.
Plexiglas is a trade name of one manufactures clear acrylic.  Acrylic may scratch, they craze before they
reach the point of total failure.  A good warning sign you don't get from glass or Lexan.

Dan H.

rjune@fuse.net wrote:

> Herve - I agree with you... temperd galss is the best to use,
> and also the most expensive based on required thickness
> for a given design deapth.  Polycarbanate (Lexan) is my second choice,
> and you are correct it has a relativly soft surface meaning that it
> will scratch if abrasive cleanners are used.  There are some products
> out there that can be used to help restore scratched lexan.  As to plexyglass for me it is never a choice.
> >
> > From: "Greg Snyder" <snyde032@tc.umn.edu>
> > Date: 2002/05/07 Tue PM 05:03:45 EDT
> > To: <personal_submersibles@psubs.org>
> > Subject: RE: Re: [PSUBS-MAILIST] Using a commercially available hatch as an emergency escape hatch.
> >
> > Hi Herve -
> > Do you think that 2 layers offers a benefit ( they quoted me for 2 layers of
> > 12mm glass).
> > Thanks-
> > Greg
> >
> > -----Original Message-----
> > From: owner-personal_submersibles@psubs.org
> > [mailto:owner-personal_submersibles@psubs.org]On Behalf Of Herve
> > Sent: Tuesday, May 07, 2002 2:16 PM
> > To: personal_submersibles@psubs.org
> > Subject: Re: Re: [PSUBS-MAILIST] Using a commercially available hatch as
> > an emergency escape hatch.
> >
> >
> > I used in my dry ambient subs, 1/2" tempered glass. cristal clear for ever.
> > Lexan gets to easy and rapidly worn out, scratched and loses its clearness.
> > Plexiglass cracks after a while under sun exposure.
> > I tested my windows in 10 Ft water column when differential pressure never
> > exceeds 2 Ft of water column.
> > Herve
> > ----- Original Message -----
> > From: <rjune@fuse.net>
> > To: <personal_submersibles@psubs.org>
> > Sent: Tuesday, May 07, 2002 1:16 PM
> > Subject: Re: Re: [PSUBS-MAILIST] Using a commercially available hatch as an
> > emergency escape hatch.
> >
> >
> > > never use plexiglass ... it is to week
> > > use polycarbinate also called lexan
> > > >
> > > > From: Ray Keefer <Ray.Keefer@Sun.COM>
> > > > Date: 2002/05/06 Mon PM 06:09:21 EDT
> > > > To: personal_submersibles@psubs.org
> > > > Subject: Re: [PSUBS-MAILIST] Using a commercially available hatch as an
> > emergency escape hatch.
> > > >
> > > > Hi Greg,
> > > >
> > > > Since your sub is ambient. If this window stays sealed at the surface it
> > > > should stay sealed at depth. The pressure inside and outside will be
> > > > even. The strenght of the frame and window only has to overcome minor
> > > > differences in pressure.
> > > >
> > > > My concern is that the window is glass and frontal position of the
> > window. I
> > > > would hate to see you run into a rock and shatter the window.
> > > > The spec says up to 3/4" tempered glass. Don't skimp, use the thickest.
> > > > Use plexiglass if you can get it.
> > > >
> > > > Also keep in mind to use this exit you will have to be on the bottom.
> > > > Else when you open the window the you will suddenly heavier with water
> > > > coming in and will sink.
> > > >
> > > > If your sub subsides into the bottom silt, sand and stuff might come up
> > to
> > > > your opening. Limiting your exit and letting stuff into your sub to add
> > > > weight.
> > > >
> > > > One last concern is you just can't open up the window. Air will bubble
> > out
> > > > and water will flood in. How violently depends on how much air will be
> > > > displaced how fast. Perhaps a valve low down in the sub to let water
> > flood
> > > > in and one up high to let air out. Once water level is above the window
> > > > opening the you can open the window without a large air bubble burping.
> > > >
> > > > Regards,
> > > > Ray
> > > >
> > > > > From: "Gregory Snyder" <snyde032@umn.edu>
> > > > > To: <personal_submersibles@psubs.org>
> > > > > Subject: [PSUBS-MAILIST] Using a commercially available hatch as an
> > emergency
> > > > escape hatch.
> > > > > Date: Sat, 4 May 2002 13:06:07 -0500
> > > > > X-Priority: 3 (Normal)
> > > > > X-MSMail-Priority: Normal
> > > > > Importance: Normal
> > > > > X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000
> > > > >
> > > > > Dear Psubbers -
> > > > > I am in need of some advice.
> > > > > As I refit the sportsub, I wanted to add an additional window that can
> > > > > serve as an escape hatch.
> > > > > I thought I would do this in the front lower section (by my knees and
> > > > > shins when sitting).
> > > > >
> > > > > My design can tolerate an oval 27" by 16".  I can fit through if need
> > > > > be.
> > > > > I am looking at a commercially available window at the following link:
> > > > > Model 71111 cut to these dimensions with the hinge removed and bow
> > > > > handles in their place.
> > > > >
> > > > > http://www.beclawat.com/bec71111.htm
> > > > >
> > > > > My question is do you think that this will stay sealed in an ambient
> > > > > cabin at a maximum of 130 feet?
> > > > > Or am I just fooling myself.
> > > > >
> > > > > Open to suggestions-
> > > > > Thanks-
> > > > > Greg
> > > >
> > > >
> > >
> > >
> > >
> >
> >
> >