O2 clean SPGs

[Scubaroo]

Does anyone using EAN40 or higher (eg EAN50 and EAN100 for deco purposes) worry about having 02 clean SPGs? Or O2 clean HP hoses for that matter? People talk about having O2 clean regs because that's where high O2 content gas will be encountering rising temperatures (when the ambient pressure air in the reg is compressed when the valve is opened), but I've never seen SPGs or hoses in the same airspace mentioned. Presumably the ambient air in the hose and SPG would also be compressed by the incoming gas from the tank.

I've seen Apeks oxygen clean SPGs available for sale on a UK website, but a lot of people say they like ScubaPro's mini SPG for deco tanks - I couldn't find any reference to these being O2 clean. Do people get them cleaned, or just not worry about it?

Not diving nitrox yet, but am looking at courses, and I would like to be using my own gear, so this is a consideration (I think).

Ben

 

[100days-a-year]

Ben,the only thing I did was to replace the o-ring and put a film of Christo-lube on it.I use all S-P minis.

 

[FredT]

NEW bourdon tube style SPGs come effectivelyO2 clean, as do PST tanks. The manufacturing techniques necessary to fabricate them pretty effectively demand it as a by-product. It takes contamination from another source to make it _not_ O2 clean.

If in serious doubt hook it to an O2 bottle and place it in a "blastproof" device (12" of 6" pipe buried vertically works nicely) and hit it with O2 at a rate 10x or better than what it would see in service. If it remains intact it's clean. If it doesn't it's cheaper to replace a contaminated Bourdon SPG than to properly clean it. To clean one to "NASA" standards for use with LOX costs several times what the gauge is worth just in solvents! Since they've got very small orifices, and are a "dead end" system, repeated O2 safe solvent immersion in cycling vacuum followed by repeated vacuum cycling in dry nitrogen is necessary to get it perfectly clean. Plan on paying two to three hundred $ or more for the cleaning if it's being done correctly.

BTW I've never seen a dive shop set up to do it properly. The last two rinses in solvent have to be in new clean solvent! As a data point the solvent I use to clean electronic subassemblies prior to wire bonding the die (the substrate has to be completely contaminant free) is only $3000/30gal drum. Fractional distillation is the only way to clean it for reuse, and that hardware is about $16,000 for a machine that processes 2 gallons a day with an 80% recovery rate.

FT

 

[Scubaroo]

So ya reckon just stick to replacing the o-ring, Fred?

 

[FredT]

Getting those tiny O-rings off and on is a PITA. Starting with an unassembled spindle you'll save over half the time it takes to disassemble, clean and reassemble a <$3 part.

 

[pescador775]

My only comment has to do with the regulator/gauge comparison. High pressure gas does not slam the hose or gauge due to the restrictor port. It acts like a bleed valve, the type that PP mixers use to fill tanks with O2. Just install a clean O ring and forget it.