Building own o2 bank

[oxyhacker]

I wonder if your instructor ever actually tried this? I don't know anyone who does unless they are traveling to remote locations abroad where air quality is really questionable. Most US shops are not going to be very happy with you bringing in your own filter to avoid having to pay them for OCA or nitrox, and the only affordable filters set up to be used this way have such limited capacity as to be of questionable value. You could buy a short full sized filter stack and plumb it to be used this way, but then you are looking at $1000+ and you could buy a lot of OCA for what that will cost you.

Better to find a shop with good air and use it. A well maintained plain ol' grade E filter system will usually deliver air that is perfectly usable for PP mixing. A good shop should have a stack of air analysis reports hanging somewhere where you can see them, and leafing through them will let you know how well their air stacks up.

But to answer your question, Coltri and Undersea Ltd. make small, not-too-expensive filters like you describe, and Lawrence factor has a larger, considerably more expensive version.

Hi.
I'm finishing my gas blender course and one of the equipments that my instructor told us, to make the top offs in local centers was a portable filter with a yoke converter, that allows to use compressor that is not ready for O2 compatible air.That is we make the partial O2 filling at home and top off at a center.Since I don't know what brand those filters are could someone tell me something about it.:huh: :huh:

Thank you.

 

[RisingPhoenix]

Indeed about filters, am lucky to have 3 stage mixing panel that is portable, but as mentioned above, only used wher elocations are remote, or air is bad (to the point of people that havent had fills through the panel complaining of taste!!)

Otherwise most places have O2 compatible air on tap here..

As mentioned above, you ned to make sure the LDS is dillignet to let your tank cool down, re-check pressures after air is added etc to get your desired percentage, unless you're diving shallow enough that a slighty richer mix might be ok!

Steve

 

[LULA]

Oxyhacker, thank you for the information,Here in portugal dive shops don't test the air coming out of their compressors, it's not mandatory (and i don't know were else in europe is) the fact is that comes mutch cheaper making the parcial O2 fillings at home and top off in a local dive center (most don't have double filtration).Here in portugal a simple transfill system with a cheap digital gauge costs 750€ almost 900 us dollars,but it pays it self.

 

[pescador775]

Lula, the kind of filter that you are referring to is called a "portable hyper filter". They are fairly large and heavy and cost a lot, probably upwards of $1000. The small in line filters that are commonly available would not serve except to remove small amounts of residual water and odor that might be present in the air of a poorly maintained compressor. These situations were fairly common in the 1950's and 60's when an LDS compressor filter system did not include molecular sieve, a dessicant. It is rare today (in the US). Like large filter systems, small inline filter canisters contain media such as activated charcoal. Fine particulates can be present in the bulk media and in the filter. A good filter canister contains a micronic filter element to remove the fine particulates from the air flow. If the filter canister only uses felt pads to screen the air then it is possible that the in line filter can actually contaminate the air flowing into the SCUBA bottle, that is to say that a tiny amount of combustible particles may end up in the tank. If the canister accepts a factory made cartridge then it is likely that a micronic disc is included inside the cartridge. The subject of particulate contamination is controversial inasmuch as the US Navy specifies filtration of about 2 microns. However, some divers with lots of experience partial pressure filling feel that the 40 micron filtering provided by fine grained dacron felt is OK, safe enough. They are possibly correct. In any case, a SCUBA tank should be inspected from time to time with regard to water and oil, the more hazardous of ordinary contaminants.

 

[pescador775]

Since the subject of Europe has come up, I am informed that Germany is looking at raising the acceptable carbon monoxide standard for breathing air--to 15ppm. It seems to me that breathing air for divers should have a lower level than that. At depth, the PP of 15ppm carbon monoxide could be the equivalent of<= 90 ppm, enough to make a diver short of breath or nauseous. This gives one pause when reflecting on portable filters.

 

[cool_hardware52]

Hi.
I'm finishing my gas blender course and one of the equipments that my instructor told us, to make the top offs in local centers was a portable filter with a yoke converter, that allows to use compressor that is not ready for O2 compatible air.That is we make the partial O2 filling at home and top off at a center.Since I don't know what brand those filters are could someone tell me something about it.:huh: :huh:

Thank you.

To make genuine Oxygen Compatible Air (OCA) you need an expensive filter tower with enough capacity to ensure a long enough dwell time. Lawrence Factor is one source. Be prepared to spend more than $1500 for the tower, + more for the cartridge.

These Ultra High Purity filters need cool, scuba ready (grade E) air to work well. This means the air should be banked and allowed to cool before passing through the portable filter.

Small, mount on your cylinder, type filters aren't going to provide OCA.

Tobin

Well that's what happens when you get interrupted mid reply. What Oxyhacker said.

 

[jonahfab]

I understand and respect your desire to DIY it on your oxygen blends. But have you done a 'business appraisal' on the idea. What I mean is, will it really be more economical for you to invest in the Oxygen bank and equipment rather than get your fills from a reliable LDS? Or are you concerned to get mixes that are not easily available locally?

Actually I found that I could get a beginning set up for less then $500, and that was based off the set up my instructor had in his garage. My Lds uses only 02 clean air, and the owner is cool with the idea since most of his instructors do the same thing. As far as cost savings I am looking long term, and if I've done my calculations right it would really onlt take the first year to recoup my expenses.( plus splitting the costs with my dive buddy helps also.) The other thing I like about the idea is diving on nitrox more often because I do feel it's safer then straight air. Having been reading through the oxyhacker and love the book.