O2 clean reg

[BigJetDriver]

Oxygen cleaning and proper o-rings are definitely necessary, BUT not all regs have HP seats that are compatible with HP oxygen.

Most Apeks and Scubapro regs can be cleaned up for O2 service.

I use a set of four Apeks TX-100 regulators. The O2 service kit includes the O-rings, and the filters. The seats are HP O2 compatible. Cleaning and an O2 compatible lube, such as Christolube, is required.

Interestingly, direct from Apeks, when fitted with the kit and properly cleaned, these regulators were approved for 100% O2 service. After Aqualung/U.S. Divers bought them, this statement was negated.(Thank you, American tort law system!)

P.S.---Parts are still available.

BJD :anakinpod

 

[scubasean]

nm

 

[Scubakevdm]

one more thing, all of my regs are nitrox compatible. shouldn't this mean that they are able to be cleaned?

Thanks for you time.

Nitrox compatible doesn't always mean 100% O2 compatible. Titanium regs, such as the SP Mk25T cannot be used safely with O2 concentrations above 40%. Most regs can be re-sealed with O2 software kit. I think someone was saying Viton, or EDPM, but we used flourocarbon O-rings for O2 service in the navy, if I recall correctly. I think that the ScubaPro O2 software set is flourocarbon too.

 

[Genesis]

OK, here's some truth for 'ya.

There is no such thing as an "O2-compatable" HP seat. It does not exist.

"O2 compatable" means that it will NOT ignite or support combustion at any reasonable combination of working pressure and achieveable temperature in the intended service at the intended FO2.

ALL HP in regs made today seats will flash if abused. ALL! This is because they are all made out of materials that WILL burn in pure O2 at even 1 ATM. Don't believe me? Cool. Take an old seat, stick it on a safe surface (e.g. welding brick), take a welding torch and turn on only the O2, place said stream of O2 over the seat and then attempt to ignite the seat using a common butane lighter. BE CAREFUL DOING THIS! It will go POOF! Kids, don't do this where you can get hurt (e.g. on a flammable surface!)

Ditto for Viton and EPDM O-rings, or for that matter, flourocarbon materials. The ugly fact is that flourocarbon materials (which includes Viton), WHEN they decompose, produce really nice byproducts like phosgene. Yeah, that's the same stuff the Germans gassed people with in WWI.

Note that light AIRCRAFT, which frequently have pure O2 systems running around (especially those without pressurized cabins!) use BUNA O-rings.

Now that's at ONE ATM. Wanna try it at 200 ATM? Uh huh.

Now why doesn't it happen OFTEN? Because seats have an adiabatic expansion happening right next to them, which makes them COLD. BUT, when you turn ON a valve, the seat is slammed shut AND you get an immediate adiabatic HEATING spike. If you do it with short hoses (little reaction time for the seat to slam closed) or worst of all, NO hoses (e.g. a reg with all the port plugs in) it'll blow reliably if you slam a "fast" valve open.

That's how they ignite and flash. Contamination just makes it more likely to happen, but I assure you that I can ignite the seats used in every reg I've seen so far.

So, when you turn ON an O2-rich bottle, hold the purge of the reg depressed. Now you have FLOW across the seat surface which produces adiabatic COOLING, and you are much less likely to get a flash-fire.

Can it still happen? Yep. Your enemy is adiabatic heating. To have a fire you need fuel, oxygen and heat. You always have fuel in a regulator, because ALL of the soft materials that seats and O-rings can be made of WILL combust or decompose if they get hot enough in an oxygen atmosphere. You have lots of oxygen. The ONLY thing under your control is heat.

This is why you don't slam valves open.

BTW, regs made of anything other than Brass (specifically, Titanium and Aluminum!) are unsafe in high FO2 atmospheres. Titanium in particular burns like hell in oxygen. Aluminum medical O2 regs were recalled a few years ago because a number of flash-fires occurred in them - duh on the manufacturers - aluminum will burn quite happily in a high FO2 atmosphere; you just have to get it hot.

BRASS, on the other hand, will NOT burn up to about 10,000 psi of 100% O2! It is therefore the only reasonably-safe material to use for a deco reg.

 

[Scubakevdm]

adiabatic

There's no need for name calling.

 

[BigJetDriver]

Genesis: There is no such thing as an "O2-compatable--(sic)--" HP seat. It does not exist.

compatible---Webster: [adj] able to exist and perform in harmonious or agreeable combination

By the terms of the definition, and in the usage presented, the word "compatible" IS correct.

You are correct, however, in your statements about high pressure oxygen, temperature, and their effects upon almost any material. Given the right set of circumstances involving high pressure oxygen, almost any material will oxidize rapidly.

BJD

 

[Genesis]

The problem BJD is that to be "compatible" it must perform harmoniously in all reasonably-expected scenarios.

That would include someone slamming open a valve on a tank full of 100% O2.

You might get away with that 100 times. You might also not. What is pretty certain though is that this is a fairly high-risk thing to do, and if you don't get away with it, the results are likely to be somewhat dramatic.

 

[WarmWaterDiver]

I concur with the above. I have worked with 100% liquid oxygen systems, using vaporizers, to enrich air for industrial combustion processes. All parts of the air / enriched air system required instrumentation for monitoring and control. The systems I'm familiar with do not typically enrich the combustion air above 27% O2. Great care is taken in terms of removing all greases, milling oils, particulates, etc. in the assembly, comissioning, and operation of these systems.

I am personally not comfortable with the concept of using my high pressure equipment (first stages, SPG's, hoses) with enriched O2 mixtures (anything with O2 greater than air) if I have used Grade E air in them, without having a maintenance service performed which includes O2 cleaning as well as rebuid again with O2 compatible (as is defined above) components. I have recently purchased a separate first stage (and will keep a specific HP hose & SPG with this first stage) for when I'm traveling to a more remote dive destination where only Grade E air is available and I'll be doing recreational diving. If between service intervals I use Grade J air in my O2 cleaned & compatible high pressure equipment I do not have the same concerns.

Compressor oils can concentrate over time on equipment surfaces. There are in-service piping modification procedures ("hot taps") I have seen routinely used on flowing hydrocarbon, hydrogen, and water systems that are not used on industrial compressed air (not even enriched in O2) systems (even at 60 PSIG operating pressure) in facilites I have worked at for this very reason. This is what I have used as guidance for my personal choices with my scuba equipment.

I am certain there are others with different experience and opinions on this matter - just putting my $0.02 in here.

 

[DA Aquamaster]

Well, not necessarily, because most manufacturers say that their regs are good for up to 40% O2. Just because a reg is good for EAN40, doesnt mean that it can handle 100% O2.

40% is pretty much the default now for manufacturers, Scubapro for example approves all their regs sold after 10-2000 for use with Nitrox up to 40%.

The only regs that the manufacturers SAY that they are good for O2 is the Oceanic Tech, the OMS reg, the Poseidon Xstream deco, Aqualung O2 (which is a clean Calypso), and maybe a few others out there (Abyss). Now, that being said, many divers clean alot of different regs, and use them with O2 against the manufacturers guidelines. For instance, Apeks, and Scubapro, and Sherwoods, etc...

Scubapro has approved the Mk 20 and Mk 25 for use with O2 mixes up to 100% at 3500 psi provided they are the brass versions of those first stages, are appropriately O2 cleaned, and have the Nitrox kit installed.

I am not sure where that leaves the MK 2 Plus, which makes a great reg for a deco bottle, or the Mk 16 which seems to be quite popular with divers with concerns about using the Mk 25 in cold water. But I suspect they would work fine with nitrox mixes over 40% as long as they are O2 clean, and the latest o-rings and service kits are used which I believe all use EDPM O-rings. Don't quote me on or take my word for it though.

 

[Genesis]

Scubapro has approved the Mk 20 and Mk 25 for use with O2 mixes up to 100% at 3500 psi provided they are the brass versions of those first stages, are appropriately O2 cleaned, and have the Nitrox kit installed.

Do you know what is ACTUALLY different between the Nitrox and "regular" kits on the Mk20/25?