2nd stage barrel corrosion

[LanceRiley]

Hi i overhauled my oxygen deco reg.
its an apeks xtx50

i got this 2nd hand.

it was overhauled 2.5years ago.

so this time im overhauling it.

I dive a mix of recreational single tank, and doubles tech.

sometimes we dive with nx50 and sometimes nx50 and oxygen.

in my last dive it was free flowing.

decided to overhaul 2nd stage as i ran out of 1st stage kits.

im having doubts on the barrel. internal is kinda corroded. im doubting the oring would seal it.

Opinion? already dipped it in citric acid… acetic acid. Soapy ultrasonic Cleaner

Should i do atill usw this for 1 more ride ?

 

[Mobulai]

I would recommend you use phosphoric acid instead (it’s far better removing the verdigris while softer attack on the chrome/zinc plating— check the TanksALot post in the thread attached belwo), but alas all acids eventually will do the same — eat the corrosion away and leave you with bare brass without the chrome plating
It seems you are almost there, and I suspect some parts were eaten away by the citric/acetic acid as they are more aggressive than phosphoric

Give it a rinse with an old toothbrush and some soap to loosen up the last bit of verdigris, one more run in an acid bath, follow by a mix of water and baking soda to neutralize the acid (so it doesn’t keep eating at the chrome), then a soapy bath for the sake of oxygen cleaning (it’s not that critical btw for 2nd stages as they present no serious risk of o2 fire, but never hurts to do it)

The oring will seal regardless unless you have scratches in an oring land/groove
The freeflow has nothing to do with it — it’s the cracking effort poppet/seat/orifice interface

Check if your orifice has scratches/knicks, might be the reason you don’t get a good seal at the poppet seat, and thus freeflowing

The unplated parts mean that you have to rinse more thoroughly from now on (overnight), and maybe do rebuilds on a shorter intervals to avoid having corrosion reoccurring and gunking the reg — again it’ll not cause a freeflow in its own (unless you have the exposed brass issue with the orifice itself as well and then verdigris accumulates causing an uneven seating surface)

Oh also, cover all the unplated surfaces with lube (cristo in this case instead of silicone) to have a protective layer against water and slow down corrosion

give this thread a look as well, some good relevant advice/content is in here

Scent/perfume free dish soap — that’s what I go for

After reading abit on the boards here thoughts and discussions by other members , I adapted their preference towards EDPM as it has better shelf life, slower degradation towards hardness (in use) and still good enough oxygen fire saftey (I believe @Tanks A Lot and @rsingler have shared these thoughts in multiple threads before — and others too)
Scubapro for example doesn’t use viton and ships EDPM (regardless of o2 clean usage or not). I suspect for similar reasons as this

Viton is commercial name of FKM; the F is fluoro-; so these funes will be containing hydrofluoric acid of some form — HF is toasty indeed

But… don’t overthink this; christolube is a respiratory irritant according to hazard labels so… it’s kinda impossible to comply this way or the other
I’d rather not have a hellfire underwater dealing with deco over off chance far ahead in life of having issues because some traces of a chemical has impacted my lungs minimally
And if your deco reg burns up — the toxicity is low prio on my concern list
You do your own risk assessment/mitigation strategy


you’ve mentioned this (twice)
What do you mean by washing service kit parts; they should be delivered grease free and already clean
Which parts do you mean specifically?
O hope you’re not washing orings

I'll continue my own thread as I'm slowly getting there…
I'm planning to service my regs in about two weeks when I hopefully get my full mine course finished.
(my first dives after the service won't be in mines)

So far I have gathered all needed tools and service kits for servicing Apeks DST and MTX-R 1st stages and XTX40/50 and MTX-R second stages. For now I want to service my nitrox/trimix regs and oxygen clean is not necessary for 1st stages. Altough I would like to do everything so that it is oxygen clean, just for practice. My regs are in good condition and I mostly dive in fresh water.

For cleaning I would like to use chemicals that are and easy to dispose. Feels like most ready made ultrasonic cleaner solutions that are sold in Finland are some sort of toxic waste.

Cleaning process:
1. Clean my tools, I have used same o-ring picks with torch o-rings, maybe I'll get another set, but still make sure my tools are clean.
2. Disassemble regulators
3. Use powder free latex or nitril gloves for cleaning and assembly
4. Wash parts (including service kit parts) to get grease off:
- Use nylon brush
- Many use Simple Green, Joy, Dawn, … which are not available (or Really expensive) in Finland.
- Anyone have suggestion for similar product available in Finland/Europe?
5. Rinse with water to get all detergent off
6. Wash metal parts in ultrasonic cleaner:
- Use white vinegar with water 1:1
- 10% can be found on all stores here
- 1-3 minutes
7. Rinse with water to get rid of vinegar and everything that ultrasonic released
8. If parts are not clean, then repeat cleaning
9. If parts look clean then rinse with sterile water
- Cheap from pharmacy
10. Blow dry with (clean) air
11. Assemble and use Christo lube on all o-rings

Questions:
1. What to use instead of simple green that is available in Finland/Europe?
- Or what not to use? There are a lot of dish washing solutions for grease removal but which one to choose?
2. Apeks service kits has oxygen compatible parts, but do you use Viton o-rings for 1st stage if it's used with 100% oxygen? Or do you just clean oxygen compatible parts before use?
Quote from Harlows Oxygen hacker:
"While viton is less likely to combust, when it does, it produces fumes that are extremely toxic, even in trace amounts. For this reason, several SCUBA regulator manufacturers have specifically recommended against the use of viton!"
3. Has anyone read this TDI Equipment Service Technician Manual - International Training Online Store and Is it worth buying?

Thank you for all the comments.

 

[Mobulai]

Check this tip as well, I don’t know if cerakote is o2 compatible or not, but I personally would worry to much about it as 2nd stages face adiabatic cooling not heating so the risk of o2 fire has a near zero chance

its likely as you suspect, either too much time or too high a concentration of acid stripped the chrome

without the chrome coating, it is vulnerable to dezincification at this point in saltwater. outside of maybe using cerakote, you will just have to monitor it and accept replacing it later on as needed.

 

[LanceRiley]

I would recommend you use phosphoric acid instead, but alas all acids eventually will do the same — eat the corrosion away and leave you with bare brass without the chrome plating
It seems you are almost there, and I suspect some parts were eaten away by the citric/acetic acid as they are more aggressive than phosphoric

Give it one more run in an acid bath, follow by a mix of water and baking soda to neutralize the acid (so it doesn’t keep eating at the chrome), then a soapy bath for the sake of oxygen cleaning (it’s not that critical btw for 2nd stages as they present no serious risk of o2 fire, but never hurts to do it)

The oring will seal regardless unless you have scratches in an oring land/groove
The freeflow has nothing to do with it — it’s the cracking effort poppet/seat/orifice interface

Check if your orifice has scratches/knicks, might be the reason you don’t get a good seal at the poppet seat, and thus freeflowing

The unplated parts mean that you have to rinse more thoroughly from now on, and maybe do rebuilds on a shorter intervals to avoid having corrosion reoccurring and gunking the reg — again it’ll not cause a freeflow in its own (unless you have the exposed brass issue with the orifice itself as well and then verdigris accumulates causing an uneven seating surface)

Oh also, cover all the unplated surfaces with lube (cristo in this case instead of silicone) to have a protective layer against water and slow down corrosion

give this thread a look as well, some good relevant advice/content is in here

Actually when i took it apart. It had a lot of salt sediments. After the acid baths… is when i took the pictures. I suspect that the interiors are already uneven due to corrosion.

And the oring in the adjustment knob isnt properly sealing?

Anyway looking for an opinion if this sill still be good.

Orifice looks fine.

 

[Mobulai]

And the oring in the adjustment knob isnt properly sealing?

Did you notice a leak there already? Or just a guess

Because oring clearance are for sure more than the thickness of chrome plating

Otherwise you have a scratch that bypasses the oring — that has nothing to do with the chrome loss

 

[Mobulai]

I wanna highlight this very important concept:
The seal happens only at the orings (and their land/grooves)
It doesn’t matter if the middle section of the barrel looks like a hilly terrain (well it might affect motion of the poppet, but not the point)

The threads AFTER the knob oring (between the knob itself and the oring on it that seals to the barrel) don’t matter for having a seal (they matter to self seal, so tha the threads don’t trap water and further corrode, but not important for the reg to do its function, seal and breathe at intended cracking effort)

It might be the case that the huge amount of salt deposits dragged along the oring sealing surface and cause a leak there; but you’ll have to confirm that not just guess it (and also means that your really don’t rinse your regs)

 

[Mobulai]

Another thought just came to mind; even if there’s no good seal at the knob, you might not get any bubbles, there’s gonna be a leak, and that leak will in turn seep water into the barrel and effectively increase your cracking effort (more negative pressure to activate air flow) and maybe also some wet breathing

It will NOT cause freeflow — this is my best guess without actually seeing the real status of the insides

 

[LanceRiley]

I actually rinse my gear after every dive, direct a hose on the knob to make sure salts and debris can come out.

No just assume that water is passing thru or seeping past the o ring for this to happen.

I divide my gear as bought new and bought 2hand. These were bought 2nd hand.

All the gears that were bought new didnt look like this…

 

[Centrals]

Test it and see what happens! As long as there is no leak then no need to worry about.
Mine(28yrs old) is far worst than that(superficially).

 

[Mobulai]

I actually rinse my gear after every dive, direct a hose on the knob to make sure salts and debris can come out.

You have to soak your gear as well, a 2nd stage isn’t a sealed system and saltwater attacka the knob from both sides of the oring