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Re: [PSUBS-MAILIST] CO2 scrubber alternatives?
Why you want a alternative to scrubbers ?
Its cheap, small and simple.
A box with 3 Kg (6 pound) works for 6-8 hours.
best regards Carsten
Robert Ossian schrieb:
>
> I am in the process of designing my first dry
> submersible, but in an attempt to extend my O2 (and my
> dive time) I am looking for an alternative to using
> CO2 scrubbers.
>
> I have been thinking of using some sort of a half face
> regulator design, simlar to the type worn by fighter
> pilots, but am still a little concerned about CO2
> levels building up in the cockpit. How can I make
> sure that the C02 is actually expelled safely?
>
> Any Ideas?
>
> --- "Dan H." <jmachine@adelphia.net> wrote:
>
> > Brian,
> >
> > The viewports I was describing are the ones that are
> > a flat disk type. The 45 degree chamfer I was
> > referring to, is not for a conical viewport. The
> > lenses I was describing have straight sides, but on
> > the external side of the lens, the otherwise 90
> > degree edge is chamfered at 45 degrees, to accept an
> > O-ring in what becomes a cavity because of the big
> > chamfer. All of my flat viewports are made like
> > this.
> >
> > There is one conical viewport in the hatch cover on
> > "Persistence". It's viewport housing does not have
> > a flat seat for the lens to sit against but instead
> > it is cone shaped. Of course the small hole end of
> > the cone is inboard and the big end is outboard.
> > This is the only viewport in my sub that isn't
> > urethaned in place also. The cone hole in the
> > housing is a complete taper from one side the other.
> > The lens is machined with the same matching taper,
> > but on the big diameter of the lens, the outboard
> > side, some of the taper part is machined away so the
> > lens has straight sides for about a quarter of an
> > inch. It is this part of the lens, where the cone
> > does not come to a sharp edge, that creates the
> > cavity for the O-ring seal.
> >
> > Two totally different types of lenses and housings
> > but both sealed with O-rings in a 45 - 45 - 90
> > degree shaped cavity. Only, as I said in the last
> > posting, I also sealed the flat lenses with
> > urethane.
> >
> > I do like the idea of the conical lens in the hatch
> > cover not being urethaned in because my hatch cover
> > latches aren't accessible from outside the sub. If
> > anyone has to drag me out of it, the best way to
> > access the inside is through this easily removed
> > conical viewport. My crew knows this.
> >
> > Hope this explains it better. If not you may be
> > able to see some of my description in pics of
> > "Persistence" during construction. I know PVHO
> > standards show both types of lenses and more.
> > (for those not Familiar with PVHO, it is Pressure
> > Vestal for Human Occupation standards)
> >
> > Dan H.
> > ----- Original Message -----
> > From: Brian Cox
> > To: personal_submersibles@psubs.org
> > Sent: Tuesday, December 20, 2005 10:54 AM
> > Subject: Re: [PSUBS-MAILIST] viewports
> >
> >
> > Dan,
> > That is some really good insight,
> > something you wouldn't necessarily find in a book.
> > Thanks, I only hope I can return the favor some day
> > to somebody in the future.
> >
> > What about the viewports that do not have that 45
> > degree taper, just squared off. Don't you have
> > some viewports like that? I've been thinking of
> > maybe using that type because of the ease of
> > machining them and just having a small tapered one
> > in the hatch.
> >
> > On the flat viewports does your o ring also go in
> > that little chamfer space? And all the same would
> > apply as far as the size of the lens and the
> > placement of the urethane sealant.
> >
> > Thanks
> >
> > Brian
> > ----- Original Message -----
> > From: Dan H.
> > To: personal_submersibles@psubs.org
> > Sent: Tuesday, December 20, 2005 05:57
> > Subject: Re: [PSUBS-MAILIST] viewports
> >
> >
> > Brian,
> >
> > The Acrylic people can tell you what the thermal
> > expansion of acrylic is. I talked to them when I
> > was doing mine but I forget the details right now.
> > It's pretty great, as most plastics are. On a small
> > diameter viewport, it's not a big deal because there
> > aren't that many inches of acrylic to expand and
> > contract, but a large diameter lens changes
> > dimension quite a bit.
> >
> > My first design followed the recommendation in
> > PVHO for a flat lens with a 45 degree chamfer on
> > it's outer edge to contain an O-ring seal. The
> > O-ring hits in three places. One is on the 45
> > degree chamfer on the lens, the other is on the
> > viewport housing and lastly on the cover ring that
> > holds the O-ring and lens in place.
> >
> > The PVHO standards also call for a flat urethane
> > cushion to be placed between the lens and the
> > housing. I guess that's so any out of flatness in
> > either the lens or housing can be cushioned.
> >
> > The problem was that the hot, 130 degree,
> > diameter and the cold, 30 degree, diameter varied so
> > much that a viewport housing made to fit the lens
> > when at it's largest, will be big enough to leave a
> > big clearance gap when the lens is cold. The gap
> > between the lens and housing when cold was more then
> > the O-ring manufacture recommended. I talked to the
> > O-ring engineers and they said that a three point
> > contact application as this application is in PVHO
> > actually forces the O-ring to extrude at a lower
> > pressure. They said, this coupled with a gap that
> > could grow quite large is not a good design. If
> > the O-ring did extrude in this design, it may also
> > take the urethane disk with it and blow the whole
> > thing into the sub.
> >
> > So what did I do? I did what worked for Captain
> > Kittredge for years. I machined my lens smaller to
> > create an 1/8 inch gap all around it circumference
> > and I made the housing so it was about fifty
> > thousants deeper then the lens was thick. When I
> > installed the lens, I imbedded it in urethane
> > sealant. This created a flat bed of urethane for
> > the lens to rest against and a 1/8 inch ring of
> > Urethane to seal the gap around the circumference of
> > the lens. For good measure, I put the O-ring in the
> > 45 degree chamfer I had around the edge of the lens
> > also. The O-ring is sort of redundant, but if the
> > urethane ever separates, the O-ring will still keep
> > the seal and as long as the urethane fills the gap,
> > the O-ring can't be extruded.
> >
> > I know I don't have the expansion room I was
> > first trying to have. But, I don't have the lend
> > pressing against bare metal and I have a good seal.
> > You can't knock success and Captain Kittredge had
> > success with this method for thirty years.
> >
> > Dan H.
> > ----- Original Message -----
> > From: Brian Cox
> > To: personal_submersibles@psubs.org
> > Sent: Tuesday, December 20, 2005 1:02 AM
> > Subject: Re: [PSUBS-MAILIST] viewports
> >
> >
> > Maybe make the lens and then measure it hot
> > and cold, then machine the viewport housing to the
> > hot dimension and get the right size o ring for
> > whatever the gap there is.
> >
> > Bri
> > ----- Original Message -----
> > From: Dan H.
> > To: personal_submersibles@psubs.org
> > Sent: Monday, December 19, 2005 20:03
> > Subject: Re: [PSUBS-MAILIST] viewports
> >
> >
> > Yep! Plexiglas is a trade name for Acrylic.
> >
> >
> > Some one wrote that you should get a copy of
> > PVHO. It's a good idea if you can get a look at it.
> > In there, you'll find the answers to most of your
> > questions.
> >
> > The one thing that PVHO didn't answer for me
> > was how to deal with thermal expansion of the
> > acrylic lens. It's a great set of standards to
> > design with if your viewport is in a pressure
> > chamber in a building, but a sub viewport can be
> > exposed to 130 degrees F in or better in the hot sun
> > and 30 degrees F in cold water. Mine has already
> > seen that extreme. If I followed the PVHO exactly,
> > my external O-ring seal would now be stuffed in the
> > annulus between the lens and the viewport housing
> > after my deep water test in cold water.
> >
> > Dan H.
> > ----- Original Message -----
> > From: Brian Cox
> > To: personal_submersibles@psubs.org
> > Sent: Monday, December 19, 2005 9:32 AM
> > Subject: Re: [PSUBS-MAILIST] viewports
> >
> >
> > "Cast" Acrylic is what to use - correct ?
> >
> > Brian
> > ----- Original Message -----
> > From: Dan H.
> > To: personal_submersibles@psubs.org
> > Sent: Monday, December 19, 2005 04:51
> > Subject: Re: [PSUBS-MAILIST] viewports
> >
> >
> > Joe,
> >
> > Look up Acrylic in a search, find a
> > manufacture you like and either E-mail or call them
> > with an inquiry about where the nearest stocking
> > distributor is in your location. That works for
> > most anything your looking for. Get a few
> > distributors names and you can bounce pricing
> > between more then one if you like.
> >
> > Isn't the internet a great thing? ;-)
> > Dan H.
> > ----- Original Message -----
> > From: JOE
> > To: personal_submersibles@psubs.org
> > Sent: Monday, December 19, 2005 12:54
> > AM
> > Subject: [PSUBS-MAILIST] viewports
> >
> >
> > Looking for a plastic supplier for
> > viewports, in the USA
> >
> > Thanks
> > Happy holidays
> >
> > Joe
>
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