Oxygen Cleanliness Levels for Submarines and Divers

Seal the metallic surfaces so that metal/oxygen contact is not possible. Can you have the interior of the flask coated with epoxy?

Does the epoxy release any gases or any type of degradation that would add to the contamination.

With the pressures involved. I would think glass lined type of flasks, the type they use for reactors.

Well... epoxy is used for tanks used in SCBA applications for fire fighters.

When maintaining an oxygen cleanliness level of zero hydrocarbons and 3 ppm contaminants in an oxygen storage flask, what amount of time is acceptable when going from purging with nitrogen taking the flask to a dew point of -20° F, to pressurizing the flask to a minimum 15 psig blanket

Don't not know what the specs for firefighters are, the ones posted seem pretty high.

Hi,

A: zero hydrocarbons is not really zero.

In any sample of air on this earth there is more then enough hydrocarbon to easily detect it:

take a vacuum chamber and a residual gas analyser (RGA) and a turbo-pump and pre-pump to establish a pressure of 10^-9 bar or below and you will get the signature of everything that was near the system.

Alcohol (any type), acetone, xylene, terpene (natural from nearby pines), ...

If you wash with a fluid then dry in 100°C oven so that "nothing" exists any longer, then store for 6 weeks you can still see the signatures of any of these hydrocarbons together with a lot of others used in production and handling.

So "zero" should be specified...

What are allowed "contaminants"?

B: if you use dry nitrogen you will not have rust problems. But I would not at all be comfortable at the idea that mild steel is used for these flasks. Gas drying is an established technology in semiconductor manufacture and air-bearing use. Primitive units dry with calcium-chloride better ones with absorption and desorption and automated switching from absorption to desorption cycle.

C: Switch with your material to stainless steel - electropolished for better cleaning options or to aluminum (I estimate without having verified that AlMn and AlMg alloys will do, AlMgSi and AlCu may be too). Get a good and smooth and perfectly sealed anodising on the Al for corrosion resistance and cleaning quality.

D: Flash rust on clean surfaces is extremely fast - and if you can see it is a thick layer. Rub two iron samples below tap-water, DI-water or distilled water with silicon-carbide grinding paper or SiC grit and you will have flash rust within minutes or seconds.

E: Any organic material including epoxi is giving off a considerable amount of volatile substances (slow at low temperatures fast at high temperatures and very fast at decomposition temperatures): non cured parts of the two components, solvents that did enter, water, gas... See the NASA or ESA manuals: Outgassing data for spacecraft materials.

RHABE