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Oxygen Amplification

06/05/2014 7:27 AM

I am looking to raise the pressure from 400 psi to 1800 psi on board an aircraft so weight is extremely important. Any suggestions ?

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#1

Re: Oxygen amplification

06/05/2014 7:46 AM

I have only one suggestion, do not try this! 400 psi is already 27 times nominal atmospheric pressure. Any pressurized container becomes a bomb when over pressurized. You are asking how to put a bomb in an aircraft.

Don't do it.

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#3
In reply to #1

Re: Oxygen amplification

06/05/2014 10:38 AM

what we are doing is taking the normal LO2 system that is presently pressurixed at 400 psi and using it to fill a 11 cuft O2 cylinder so that the loadmasters and flight crew can go about their business in a military enviroment. We can increase the present 5-10 minute duration to 1 hr by fillling the same cylinder to 1800 psi

FYI, in normal commercial aircraft configurations the O2 cylinders you see up in the front are pressurized at 1850 psi.

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#4
In reply to #3

Re: Oxygen amplification

06/05/2014 11:42 AM

I never had a doubt that qualified mechanical design team can design and fabricate hardware to contain a gas at 1800 PSI on an aircraft. They will also know the relevant FAA tests required to certify their design.

Your question only demonstrated your ignorance on how to achieve your desires. You initially did not present any competence.

Now you give us some data of your situation and background. I'm concerned that this is for a military environment. I suspect the lower pressure standard was not capriciously set.

Why are you not using liquid oxygen in these LO2 systems. Increasing the boil off pressure will not make a significant difference in the quantity of oxygen carried. The expansion of the liquid to gas will greatly help here.

I also do not grasp your implied math. Increasing the pressure by a factor of 4.5 will not multiply 5 minutes into 60 minutes.

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#22
In reply to #3

Re: Oxygen amplification

06/06/2014 1:43 PM

Instead of liquid oxygen, may I suggest using "solid oxygen" as your source? Oxygen "candles" based on containers of sodium chlorate are already in use as the emergency oxygen supply for passengers in aircraft; they weigh much less than a high-pressure cylinder. They are extremely simple to use and the relatively high cost of the oxygen supply should not be an issue for a military application.

http://en.wikipedia.org/wiki/Chemical_oxygen_generator

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#2

Re: Oxygen amplification

06/05/2014 7:49 AM

Raising the temperature from 25°C to about 1080°C should do the trick.

If that's not possible, can we have some more information, please?

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#5
In reply to #2

Re: Oxygen amplification

06/05/2014 11:58 AM

It is a military application and it is using Liquid O2 (L02) to generate the 400 psi. I woulds like to get it up to 1850 psi to charge the HP cylinder of which then it will handle 60 minute duration at 311 liters. (of course depending upon the flow rate)

Not sure why you appear annoyed...

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#6
In reply to #5

Re: Oxygen amplification

06/05/2014 12:12 PM

Since it is liquid oxygen, changing the pressure will do nothing about the amount of oxygen carried. Liquids are not compressible.

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#7
In reply to #6

Re: Oxygen amplification

06/05/2014 12:14 PM

I think you're filling these tanks based on the pressure and not the weight.

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#9
In reply to #7

Re: Oxygen amplification

06/05/2014 12:20 PM

when the pressure guiage on the cylinder being refilled hits 1850 psi it will be filled. This is the normal way on aerospace applications that we see the fill status on all cylinders....not the weight.

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#8
In reply to #6

Re: Oxygen amplification

06/05/2014 12:18 PM

I see the issue now, I am trying to take the 400 psi available on the airc raft from LO2 and fill an 11 cu ft 1800 psi cylinder...the 400 psi is what is available and I want to raise that to 1850 psi to fill onboard the cylinder !

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#10
In reply to #8

Re: Oxygen amplification

06/05/2014 1:01 PM

You'll only be able to do that by raising the temperature, Mildred.

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#13
In reply to #6

Re: Oxygen amplification

06/05/2014 6:47 PM

Your comment is still right, but just as and FYI, pretty much everything is compressible.

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#14
In reply to #13

Re: Oxygen amplification

06/05/2014 7:20 PM

For a moment I thought you were going to suggest enough pressure to make collapsed matter.

As Wikipedia states, liquid oxygen has an expansion ratio of 1:861. If they're getting only 10 minutes of breathing time using boiled off liquid oxygen then something else is wrong.

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#15
In reply to #14

Re: Oxygen amplification

06/05/2014 9:07 PM

No argument from me on any of that.

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#17
In reply to #5

Re: Oxygen amplification

06/06/2014 8:48 AM

No one is. It's just a fact of life, like mold on cheese. Just carve that annoyed comment off and give it to the dog. She loves it.

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#21
In reply to #5

Re: Oxygen amplification

06/06/2014 10:32 AM

I assure you I'm not the slighted bit annoyed. What gave you that idea?

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#11

Re: Oxygen Amplification

06/05/2014 1:02 PM

You are wasting your time here.

No one here, except maybe Anonymous Hero has the training and certification needed to advise you.

Go here:OK-09-439 - Federal Aviation Administration

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#12
In reply to #11

Re: Oxygen Amplification

06/05/2014 1:06 PM

thank you, there are ways as in an O2 booster pump but too heavy

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#16
In reply to #12

Re: Oxygen Amplification

06/05/2014 10:55 PM

There are commercially available "pressure boosters" for air use. They are normally used to raise the pressure of lower pressure air cylinders (2,000psi cascades) to 4,200 psi for use in newer SCBA (Self Contained Breathing Apparatus) air packs worn by firefighters, etc. These are not cheap and are heavier that you would think. They still require relatively heavy supply cylinders and normally a high amperage 12v supply. Contact a manufacturer (sorry I forgot who makes them) of them and see if they are available for oxygen use. Go to a library and look in FIRE ENGINEERING or FIREHOUSE magazines. Also try your local fire house and the personnel there.

Why not take 4,200psi fiberglass light weight cylinders (like those from newer SCBA's) and supply from those. Set up a bank of them and supply gas from them. A back carried unit with a larger of the two sizes normally used lasts for 1 hour at a normal consumption rate.

What ever you do, don't do it yourself! There are companies out there who make equipment to do things similar, but not exactly, to what you want to do. Why not contact Scott, Survive-air, MSA and other SCBA and booster manufacturers and see what they may have. If no luck with them ask them who makes there units and contact them.

Good Luck, Old Salt

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#18

Re: Oxygen Amplification

06/06/2014 9:08 AM

Here is what I understand you are asking: You have a system that takes liquid oxygen and converts it (probably through a heat exchanger) to just above 400 psi for refilling O2 bottles to 400 psi. You want to instead fill bottles rated for 1800 psi to increase the bottle use time. I would recommend contacting the Engineering company that designed the system and propose a change. I have seen similar systems on the trucks that delivered liquid nitrogen to my freeze seal sites. The point is they are "engineered" for specific pressures as are the bottles being filled. Contact the "engineer" he understands his initial design and all the hazzards associated in stepping up the pressure.

This is not something to monkey around with. Liquified gas systems are dangerous enough on land where you can walk away from a leak. Aircraft designed for pure O2 atmospheres have exploded (Appollo 1). Suggest to the experts a different design. Maybe the military will give you a Beneficial Suggestion Bonus.

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#19

Re: Oxygen Amplification

06/06/2014 9:54 AM

Have you looked into a pressure amplifier?

http://www.haskel.com/Haskel/en/Products/Air-Pressure-Amplifiers

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#20
In reply to #19

Re: Oxygen Amplification

06/06/2014 10:11 AM

excellent suggestion, thank you !

Lee

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#23

Re: Oxygen Amplification

07/01/2014 5:04 PM

I'm kinda late on this one, let's see if I get some feedback:

I am under the impression that the US military is migrating away from LOX systems as a source of ABO.

http://dimo.com/military_aviation_oxygen_systems.htm

Would you tell us where you fit in the food chain, and why this particular task has fallen on you?

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#24
In reply to #23

Re: Oxygen Amplification

07/01/2014 6:04 PM

My name is Lee Delellis (go to linkedin) and you'll see where I fit in. I own my own company that only works for AFSOC and SOCOM for special projects. From your website, it appears that you ,may thinmk I am a competitor but in reality it's just as feasible to use hyour company to solve some of the app's I have. Currently I am working with AFSOC on a project to utilize 400 psi availble on the present `C130 systems with a goal of filling HP cylinders musch the same as they presently fill the walk around bottles. Lox is what they have now so that's what I have to work with

thanks:


lee DeLellis

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#25
In reply to #24

Re: Oxygen Amplification

07/01/2014 6:23 PM

Not affiliated with DIMO Corp. If they can help you, give 'em a call.

Perhaps contact Cobham as well: https://www.cobham.com/media/76845/SYSTEM%20C-130%20OBOGS%20ADV10549.pdf

Best of luck to you.

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#26
In reply to #24

Re: Oxygen Amplification

07/01/2014 7:16 PM

As you'll probably discover (if you stay around that long), the "older" members here very rarely, if ever, promote themselves, or ideed give any hint to any company or establishment to which they may have a connection.

It becomes tiresome to type "usual disclaimers apply" or whatever after posting every link to information which may help an OP (Original Poster, i.e. whoever started the thread; in this case you).

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#27
In reply to #26

Re: Oxygen Amplification

07/01/2014 8:34 PM

been around for 20 years, probably for 20 more and that's why I responded the way i did. I answer other's questions as well as ask my own amd life is good. I hate reinventing the wheel and wasting peop-le's time

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