O2 Cleaning of Primary Regulators - Should they be Piston Only

[Peter69_56]

We are taught in O2 Clean class that all items must be non Nitrile/rubber as they are fire risk, yet many primary regulators have a diaphragm made of what appears to be a rubber compound, along with, in my regulator a special flat O ring which I don't seem to see in Viton. This regulator (an AquaLung Legend) and had been cleaned previously by a well known Aussie Peninsular dive repair centre. On pulling it down I found not only the diaphragm, a nitrile flat O ring (backup O ring), and another odd sized O ring still nitrile.

Thus my query is; should O2 clean regulators be only piston regs if they are going to be used for up to 100% O2 on the basis that all components can then be Viton (as all sealing components are then O ring in design?).

If so, why then do LDS supposedly O2 clean regs that have diaphragms in them? Why do O2 clean courses not say this?

 

[jwelburn]

The diaphragm is on the low pressure side and will not see enough pressure to light up.

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[Peter69_56]

The diaphragm is on the low pressure side and will not see enough pressure to light up.

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Whilst I appreciate what you are saying, there is no distinction in anything I have read or seen to date that actually states that its ok not to clean the LP side (as its not enough pressure to "light up"), or not to worry about using rubber/nitrile content.

 

[Peter69_56]

Well I am deafened by the silence. Virtually no response?????

I now find that if a primary reg has a backup O ring it is near impossible to find a Viton replacement? Perhaps a regulator unsuitable for oxygen? Aqualung legend. A regulator cleaned by a LDS and put back into service O2 cleaned with Nitrile backup O ring and plug seat nitrile O ring, apparently OK to use?

My gut feeling is, although there is some risk in O2 fires, much is made of it by LDS to ensure clients come to them in fear, to ensure more money in the bank. Yes there is a risk, however if you take reasonable precautions the risk appears lower than portrayed. Yes things burn in O2 rich environment, but take reasonable precautions regarding flow rates and fuel material and there is low issue.

 

[Mike.D]

I have no experience with O2 cleaned regs or the procedures/theory behind it however I was under the impression that unless the O2 environment your o-rings are subjected to is pressurised, then you can simply clean and re-use the parts in question as the risk of fire will be minimal. I'll put this question forward to my reg tech and see what he has to say.....


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[Peter69_56]

I have no experience with O2 cleaned regs or the procedures/theory behind it however I was under the impression that unless the O2 environment your o-rings are subjected to is pressurised, then you can simply clean and re-use the parts in question as the risk of fire will be minimal. I'll put this question forward to my reg tech and see what he has to say.....


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From my TDI course, Nitrile is a no no. But there we are, using nitrile backup O rings and rubber diaphragms. In particular in the secondary regs as well. In all reality, I suspect the secondary regs are low risk given the low pressures, however it doesn't stop enterprising LDS for taking money on a yearly basis to ensure they are "supposedly" O2 cleaned to ensure less fire risk. I guess my beef is that industrial use of O2 doesn't have the hype similar to diving, and yet we hear little if any about O2 fires. Given the lack of care and responsibility when using industrial gases and regulators, we would expect to see significant safety issues yet we don't. This then suggests we are going somewhat overboard on the issue.

In saying that, I don't dismiss O2 fires as ridiculous, I have had related to me on 2 occasions where rebreather gear has caught fire on boats, once where the rebreather gear was lost over the side, and another where it caused the loss of the boat. It does happen, however the actual causes would be interesting.

 

[Mike.D]

however it doesn't stop enterprising LDS for taking money on a yearly basis to ensure they are "supposedly" O2 cleaned to ensure less fire risk. I guess my beef is that industrial use of O2 doesn't have the hype similar to diving, and yet we hear little if any about O2 fires. Given the lack of care and responsibility when using industrial gases and regulators, we would expect to see significant safety issues yet we don't. This then suggests we are going somewhat overboard on the issue.

You pose a very interesting question there...... Hopefully someone can clarify this a little.....


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[Subcooled]

should O2 clean regulators be only piston regs

If that were true, then every tech diver in Finland would be dead. They are not. The most common first stages for O2 are Apeks DS4 and DST (both are diaphragm regs). Some use Poseidon.

In order to get a fire going you need oxygen, something that reacts with it, and some heat. Heat you can get from a sudden pressure shock. The more pressure the bigger the shock and the higher the temperature. There's a slight difference between "300 bar at once" and "10 bar at once".

 

[Dr. Lecter]

Whilst I appreciate what you are saying, there is no distinction in anything I have read or seen to date that actually states that its ok not to clean the LP side (as its not enough pressure to "light up"), or not to worry about using rubber/nitrile content.

As one who concerns themselves about O2 cleaning the LP side, you must be able to tell me how to O2 clean my teeth.

I'm a fan of pistons myself, but are we sure the diaphram is a rubber compound and not a silicone compound?

 

[Peter69_56]

As one who concerns themselves about O2 cleaning the LP side, you must be able to tell me how to O2 clean my teeth.

I'm a fan of pistons myself, but are we sure the diaphram is a rubber compound and not a silicone compound?

Whilst I am not positively sure, it is the original diaphragm and certainly appears rubber and not silicon using a Mk1 eyeball, which has not been calibrated for rubber, latex or any other nasties.

As for the LP side of the system, I agree the risks are somewhat lower regardless of their condition (to some degree).

I am just talking about what I have been trained to do (as compared to my gut instinct). My "personal" opinion is that we should make effort to ensure that we minimise rubber/nitrile and degreased throughout the whole system thus minimising fuel and potential risk, however if the LP side does contain less than ideal products (nitrile but not grease), the risks are much lower than on the HP side.

I was reading a story where a HP oxygen cylinder caught fire due to the use of 2 sealing washers in the yoke assembly. Obviously causing a HP leak with sufficient friction (heat) and fuel to burn. The risks therefore on the HP side are real and high. I would assume similar to doing partial pressure fills, the care factor should be higher than with say a secondary regulator.

My gut feeling is we are taught the technically correct way (for legal reasons as well as "learn the right way" regardless of what you do in the end), however if reasonable care is used (rather than totally technically correct) the risks are low. My real beef is that it is apparent to me that some people use the fear tactic to take advantage of the general public. I have seen (and been exposed to) both sides of this, those who are ridiculously stupid and think there are no risks at all thus take no care, those who are fair and reasonable (a balance between the technically correct and the stupid), and those who take advantage and rape and pillage. Unfortunately (in my opinion) those who are fair and reasonable are in the minority.

Anyway having finished my rant on the subject, getting back to your post, mmmmmmmmmm maybe that special Colgate toothpaste, low O2, low drag, hi vis, high sheen. I think that will do it and prevent you from self combusting into a ball of flame.

I have found it interesting that there is not much opinion about it.