Re: [PSUBS-MAILIST] Dome Calculations

["glen brown" <glenbrown@vodamail.co.za>]

Howsit
A piece of conveyor belt will be a good seal and wont fail just cut it to 
shape with a sharp knife its also flat and you can get it in different 
thicknesses but must be well cleaned on assembly .As divers when 
decompressing in a chamber we don't latch the door we just hold it against 
its seal lightly .But I can assure you wont open the door
even with the slightest pressure change .You would have to flood your sub to 
equalize the pressure. if you use
a hydraulic ram to break the seal it would have to  push the dome sideways 
which would alter the design. to break a seal sideways would probably not 
even use a 10th of the energy as outwards but could be unpractical.
Regards Glen
----- Original Message ----- 
From: "James Frankland" <james@guernseysubmarine.com>
To: <personal_submersibles@psubs.org>
Sent: Tuesday, August 26, 2008 4:02 PM
Subject: [PSUBS-MAILIST] Dome Calculations


Hello Everyone

Progress on my sub has been slow recently, but i have managed to get a few 
things done including a change to the possible design for the removable 
front dome mounting system that i am adding instead of the 15" flat port 
specified on the plans.

I have made some changes to my original design as a result of reading 
Staichows book and with some advice from members of the group.

http://www.guernseysubmarine.com/index_files/Page12229.htm

I would really appreciate if you could take the time to have a look and let 
me know what you think of this idea.

Points to note\questions.

1.  The "O" ring groove has gone and been replaced with a 1mm bead of 
sikaflex sealant.  Bearing in mind the idea of this design change is so the 
dome can come out in an emergency, do you think this amount of sealant will 
stick it permenantly and prevent removal, even with a good kick from the 
inside?  Could make it thinner, 0.5mm?

2.  The inside diameter of the ring meets exactly the inside diameter of the 
dome.  (The 32mm bit on the second picture).  Should it be a bit larger? 
35mm?

3.  I do not have the ability to do FEA on this ring, so based on the "rule 
of thumb" that says you should replace the amount of material you remove, i 
have calculated volumes of the ring and the removed piece.  The figures are 
shown at the bottom of the page.  The endcaps are spun and thicker than 
specified on the plans.  13mm at the rims ranging to about 10mm at the 
centre.  So, exact calculations for volume of this are difficult.  If based 
on the worst case scenario of 13mm all over, the volume of weld in ring does 
not cover the "rule of thumb".  Should i add an extra 10mm to the thickness 
of the ring, bearing in mind the endcaps are already quite a bit thicker 
than needed.

Does that make sense?  I've not done one of these before so i think its 
better to ask silly questions now and avoid mistakes or accidents in the 
future.

Again, this is still just an idea at this stage and could all change, 
depending on how things turn out.

I appreciate any advice, good or bad.

Regards
James







__________ Information from ESET Smart Security, version of virus signature 
database 3387 (20080826) __________

The message was checked by ESET Smart Security.

http://www.eset.com




************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003.  Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.

If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
	removeme-personal_submersibles@psubs.org

Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.

PSUBS.ORG
PO Box 53
Weare, NH  03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************