O2 clean hoses?

Hi,

I was thinking about getting my standard gear O2 cleaned during the next revision - but the service centers always talk about cleaning the tank and replacing parts in the regulators with O2 compatible lubricant and O-rings. So far so good...

...but I was wondering: don't the hoses need to be O2 clean too???
How would you achieve that?
...and what about the finimeter? :huh:

Thanks for helping me out here!

Clem

I'd only ever bother with O2 cleaning the cylinder. Regs won't see a high enough ppO2 (pO2 if you like) to justify it in my opinion. A cylinder on the other hand can see very high O2 partial pressures when filling.

It all depends on the O2 percentage, if you are only using standard Nitrox ie up to 40% then I wouldn't bother with hoses, regs etc but you will need your cylinder O2 cleaned for anything other than air (21%). The method used in the UK for filling cylinders uses 100% O2 and then topped up with air to achieve the correct O2 percentage.

Not everywhere.

Indeed, not absolutely everywhere blends nitrox by partial pressure filling but most do. Even if they don't partial pressure fill they might still insist on an O2 clean cylinder.

These dive shops are odd places.

Only if you use 50% or higher, then you need to get your hose, reg and first stage 02 cleaned. other wise they will be ok to use on nitrox.
Cylinders need to be 02 clean
ATB
wrekrab

I know plenty of people using pure O2 with no cleaning or regs and hose. ALso the theoretical number always used to be 40%.

Shouldn't be a prob if supplied from a trusted filtered source. However, having seen the effect when pure O2 comes in to contact with a contaminant, I think extreme caution is the word if in doubt.

For me this still comes down to the partial pressure. Pressures that regs see are still pretty low.

Am I missing something?

I thought with 200 bar of an 80% deco mix at the surface the first stage would see a PP02 of 160+ bar?

Even the second stages will see 10 bar at their input.

That's more than than the PP02 my cylinder would see getting a fill of 40%, and that needs to be O2 cleaned...

I should have said the low pressure side of regs. The high pressure side wil see exactly the same that the cylinder sees.

80% O2 at intermediate pressure of 10 bar (Normally lower than this) = 8 bar that the regulator hose or second stage will see.

Partial pressure filling a 32% cylinder from empty will mean adding 32bar of O2 before topping up with air. The cylinder will then see 32 bar of O2 pressure with just the O2 added and 74 bar of O2 pressure when full.

With this example the hose will see a significantly lower O2 pressure than the cylinder.

Even pain old air will exert an O2 pressure of around 49 bar in a full diving cylinder.

The procedure for cleaning hoses is usually determined by following the cleaning media manufacturer's guidance. I find Biox a pretty effective media for most breathing apparatus applications but others are available. If this link works (I'm not great on computers!) have a look at section 10 for a more detailed breakdown on cleaning hoses.

http://www.bioxint.com/files/Latest%20Diving%20Spec.pdf

In our commercial environment we clean, inspect and verify anything that comes into contact with over 21% O2, this is a very conservative approach that stems more from a concern about the consequences of failure than their likelyhood. It certainly is not a universally adopted approach. I'm a fair bit less fastidious about it on my personal diving equipment but still think high FO2 mixtures demand respect.

A warm Simple Green solution works as well. use distilled water so no residue stays behind. Clean hands are a must. If that's an issue, use powderless latex gloves. Using a small funnel to run the solution through the hoses a few times will suffice and then rinse thoroughly. Don't bother doing the inside of the HP hoses, only soak the ends in the solution and clean with a clean toothbrush. The pinhole inlet of the HP hose will prevent a fast introduction of a gas into the hose (works as an ABS brake system) and reduces the chances of adiabatic compression, which is the cause for the heating, which may lead to flashing or explosion of your reg =)

So if I stick a flow restrictor on my Drive Trucks breaking system, I get ABS?? Cool......Off down to Halfrauds.