[PSUBS-MAILIST] penetration schedule
Alan James via Personal_Submersibles
personal_submersibles at psubs.org
Fri Aug 14 22:27:46 EDT 2015
Thanks Sreve,those links may be handy.Have a daughter in South Yarra.Alan
From: Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Sent: Saturday, August 15, 2015 1:09 PM
Subject: Re: [PSUBS-MAILIST] penetration schedule
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.l2563http://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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