[PSUBS-MAILIST] penetration schedule

Fri Aug 14 21:09:26 EDT 2015

Hi guys,
+1 for the Oxy Hackers Companion - I learnt almost as much from that book
as from working with oxygen in industry (among other things, I design and
manufacture HP oxygen systems for a job).

*Shameless plug:* Through my side business TFM Engineering (still a work in
progress), I have copies of the oxy hackers guide for sale on ebay down
under if anyone needs one, also a bunch of oxygen valves, hoses, cylinder
fittings, SCUBA fittings and other things.  They are typically for tech
divers, but would be useful for psubbers too...
http://stores.ebay.com.au/tfmengineeringaustralia?_trksid=p2047675.l2563
http://www.tfmengineering.com.au/

Teflon tape is fine, but highly recommend dedicated oxygen service Teflon
tape (probably just the same stuff but clean/degreased) - Unasco green
"oxygen" tape is what we use exclusively at work, it's expensive like Hank
found, but lovely to work with.  4-5 tight wraps is good, but try to make
sure you don't have any hanging off the bottom of the thread that may get
in the flow path.  I also have some cheaper stuff that does the job.
Regular pipe goop is a very bad idea - you can get specialised oxygen stuff
(Ie. LOX8 paste) but it's very expensive.

Stainless will burn in oxygen, but it's pretty hard to get started (think
of a wet hardwood log) and is pretty commonly used for both fittings and
tubing in industry for oxygen service, even up to 250+bar (~4000PSI).
Brass/bronze is better though if practical (and the fittings are usually
cheaper) as it won't ignite at all.  Copper tubing with brass compression
fittings is nice if you can find copper tube and brass fittings rated for
the pressure (be careful), but if you use SS tubing you have to use SS
compression fittings to get them to bite - don't use SS tube with brass
compression fittings.

Key thing is to keep the velocity down and try to avoid impingement points
- ie. sharp corners (ie. elbows) or dead ends (ie. gauges, closed valves).
This is commonly an issue on initial pressurisation. Also to properly
oxygen clean the system and scrupulously keep it that way.

And to put it in perpective - even the most oxygen-compatible elastomers
(Viton, sort of EPDM) and plastics (PTCFE/PTFE) are waaaay easier to burn
than SS, and you will probably find these in the most
critical/high velocity places like valve and regulator seats as a standard
thing.

Cheers,
Steve
(Melbourne, Australia)

On Sat, Aug 15, 2015 at 6:36 AM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> There is am O2 friendly thread tape, I paid 20 dollars for a roll.
> Hank
>
>
>
> On Friday, August 14, 2015 2:29 PM, Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> Have to check, I thought Teflon tape was OK. But you have to use only
> needle valves not ball valves, only special grease, O2 compatible O rings
> lubricants, etc. I would normally only use Swagelok type compression
> fittings anyway, whether its O2 or anything else.
>
> On Fri, Aug 14, 2015 at 4:20 PM, Brian Cox via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Alec,
>             So the other issue is that you don't want to use any pipe dope
> or Teflon tape in your system which could be a source of fuel.  So getting
> from point A to point B if your O2 tank is outside has to be done with just
> compression fittings?
>
> Brian
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] penetration schedule
> Date: Fri, 14 Aug 2015 16:03:49 -0400
>
> I believe the point is that brass/bronze/copper is less likely to ignite
> than SS, so they avoid using SS for piping in the O2. Plus, you need to
> clean everything so the fact its removable facilitates cleaning. Having
> said that, on Snoopy it all goes through SS -- but there's a regulator
> directly on the tank so I'm only dealing with low pressure O2. It is the
> high pressure lines that are most critical.
>
> Alec
>
> On Fri, Aug 14, 2015 at 3:32 PM, Brian Cox via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Have the book.    Yes Oxygen is interesting stuff, not to be messed with
> !   Can make anything combustible.  Still not clear on the bronze issue
> however.
>
> Brian
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] penetration schedule
> Date: Fri, 14 Aug 2015 10:10:01 -0400
>
>
> Hi Brian,
>
> I highly recommend a very small yet invaluable book Dan Lance once pointed
> me to. It is called The Oxygen Hacker's Companion, and the author is Vance
> Harlow. Oxygen is one area with specialized requirements that, if ignored,
> can result in a really bad day. Please be sure to read that book before you
> build anything that will handle O2.
>
> Best,
>
> Alec
>
> On Thu, Aug 13, 2015 at 11:58 PM, Brian Cox via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hank,
>              Can I put a bronze bushing in a ss coupling, if that is
> necessary for the O2?   Does the O2 need to not go through stainless?
>
>   I had a bad experience connecting stainless nipples into a
> stainless 90,  it galled so bad that I ruined the nipple getting it out of
> there. Maybe I just need to use more Teflon tape.
>
> brian
>
>
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org
> >
> To: "Personal Submersibles General Discussion" <
> personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] penetration schedule
> Date: Thu, 13 Aug 2015 20:46:45 -0700
>
> Hank,
>              It seems to me that it's easier to weld in couplings rather
> than nipples, I suppose it's just preference.   I sort of have a trim tank
> already with my forward hard ballast tank, I'm just not sure at this point
> whether or not that will be enough control.  A way to deal with varying
> loads is probably something I need to address, but I don't want to give up
> valuable cabin space for it.
>
> Brian
>
> --- personal_submersibles at psubs.org wrote:
>
> From: hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] penetration schedule
> Date: Thu, 13 Aug 2015 18:23:16 +0000 (UTC)
>
> Brian,
> I would add a few nipples and cap them off, you will want them down the
> road.
> A trim tank may be a good idea for such a heavy sub, unless you have real
> powerful vertical thrusters.  I find when I take a passenger, even my
> daughter Roman who is light as a feather, I am always quite over weight.
> That is no problem at all in a Gamma size sub because the vertical
> thrusters have enough jam to stop the sub hitting bottom.  A trim tank
> would be good to keep you closer to ideal weight, or have lots of small
> weights to take out.  I foolishly made two rather heavy lead weights.
> Are you running your O2 through a ss nipple, is that okay, I am planning
> to do that for external O2.  I remember talk about the K subs needing a
> Bronze fitting or something like that.
> Hank
>
>
>
> On Thursday, August 13, 2015 11:52 AM, Brian Cox via Personal_Submersibles
> <personal_submersibles at psubs.org> wrote:
>
>
> Hank,
>             Here are all my penetrations:
>
> Front hard ballast tank
>  1.   flood valve -  1/2" ss rod thru hull
>  2.   vent valve
>  3.  air inject    -  ss coupling
>
> Main ballast tank (soft)
>  1. flood valve  - ss 1/2" rod thru hull
>  2. air inject
>
> mechanical penetrations:
>   1.  front flaps       - ss 1/2" rod thru hull  (all)
>   2. back flaps
>   3. motor turning   ( steering )
>
> Breathing Oxygen  -  3/4" coupling  or smaller  ( will bush)
>
> Flood Valve  - 1 1/2"  - ss coupling  ( near bottom)
>
> main ballast HP air in   -
>   #1 - 3/4"  ss coupling
>   #2 - 3/4"     ( will have bushings to 1/2" or smaller)
>
>
> Gauges
>   1.  Temperature  - 1/2"   ss coupling
>    2.  Pressure -    1/2"
>
> Release buoy
>   1.  1/2" SS rod thru hull
>
> Equalizing valve
>   1.  3/4" coupling
>
> Drop weight
>    1.  7/8" ss rod thu hull
>
> Hatch dog thu hull
>  1.  7/8" ss rod
>
>  Is there anything that I obviously forgot ??      All my electrical will
> be going through a separate viewport fitting.
>
> So far I have the front trim, hatch , but no air yet.
>
> Not sure if I want to have a small trim tank in the main cabin or not.
>
>
> Brian
>
>
>
>
>
>
>
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