Oxygen gas charging station

[BADVE]

I am engaged in a project that involves a portable oxygen vehicle for charging 350 bar oxygen into air craft (military application).

can soem body tell me about the precautions athat are necesaary for handling oxygen ?

Regards

 

[SandeepRaheja]

Check out this link:

http://web.princeton.edu/sites/ehs/labsafetymanual/cheminfo/oxygen.htm

and also:

http://eweb.processplants.boc.com/msds/msds.htm

for some good data/advise on oxygen handling..

If u require oxygen compression, then consider Vertical Labyrinth Piston Designs from Sulzer Burchardt. These have the repute of being the most reliable and safe compressors in oxygen service. Diaphragm compressors may be another choice(not much feedback here, forum may please advise... ). Lubricated compressors are a catastrophy and even non-lube recips must be avoided

good luck.

 

[Montemayor]

Badve:

There are many precautions that I could easily list out for you involving the transfer of 350 barg Oxygen. However, the best and most authoritative way to learn about the hazards and techniques involved is to buy & read the CGA (Compressed Gas Association) book on compressed gases titled: "Handbook of Compressed Gases". In it, you'll quickly be oriented with the criteria and the subject matter involved in applying and transferring Oxygen and other gases.

As an example of what you should be looking out for is the inclusion of oil or grease inside piping meant for Oxygen use. I highly recommend you insist on a 100% assurance that all piping is 100% oil/grease or hydrocarbon-free. This includes checking that any water used in a hydrostatic test on the pipe is totally oil and grease-free. Additionally, I would run an oil and grease solvent through the piping to ensure that it is, in fact, free of any hydrocarbon substance prior to being filled with Oxygen. (of course, you have to purge and evaporate the residual solvent - more expense and labor, typical of Oxygen installations). The big concern in an Oxygen application is not the high pressures used or the gas itself; it is the potential, dangerous mixture of pure Oxygen with a readily oxidizable substance, such as a hydrocarbon. This is never to be allowed or credibly achievable. Mechanical engineers will recognize the product of such a mixture as an explosion.

Also, bear in mind that the B31.3 Process Piping Code is a mechanical code; this has nothing to do with the ultimate hazard and danger when dealing specifically with Oxygen: it will oxidize efficiently and instantly if given the right opportunity - in other words, it will detonate any hydrocarbon it comes in contact with under the right conditions. Your application is very process sensitive and you should consider the process needs and precautions rather than just applying strictly mechanical codes in his instance. There are existing standards for Oxygen service within some organizations - especially producers like Air Products, Praxair, Liquid Air, etc. These people can give you all the correct and safe guidelines to put your Oxygen system into service under the best and most experienced guidelines and standards - besides those of B31.3. You may, in fact, be purchasing your Oxygen from such suppliers and it would be a smart move to get their expert advice on how to test, clean, and ensure a safe Oxygen piping system.

 

[iainuts]

Montemayer mentions the CGA codes, but to be more specific, CGA G-4 and others in that series are the ones you need in order to design any oxygen systems. You can purchase them from CGA here:

http://www.cganet.com/publication.asp?mode=keyword&id=149

Of course, flamability is the number one concern. Along with an ultra clean system, choice of materials is extremely important. Even stainless steel piping is flamable in pure oxygen at a pressure greater than a few hundred psi. Stainless, carbon steel and aluminum are flamable at 350 bar. Brass and copper are the best materials, along with most Nickle alloys such as Monel. Plastics, such as are used for valve seats and packings, are limited to the florocarbons (ie: Teflon, Kel-F, PFA, etc... ) and there are a few elastomers, most notably Viton, that are generally acceptable for use. Lubricants include Krytox, Halocarbon and a few others. Any good material compatibility guide can provide other recommendations.

Montemayer also mentions the large industrial gas companies (I work for one). Although those companies might give customers advice about designing oxygen systems, they generally won't provide you any of their in house specifications. The problem regards liability.

 

[sms]

And speaking of liabilty, oxygen is very dangerous and you really need to bring in someone with experience. Trying to get advice here is not appropriate in my opinion.

-The future's so bright I gotta wear shades!