Nitrox o2 cleaning question

[rysmith]

So to start I had all of m tanks o2 cleaned when I got my nitrox certification because my LDS uses partial pressure blending. I recall him saying(and this could totally be me having a lapse in memory) that if I went anywhere that uses a continuous blend method that I would contaminate my cylinder and then have to get it re-cleaned( he then listed a few sketchy places in my area to get air fills). My problem is that my LDS is shut down right now because the owner has to take care of some personal stuff and the only place I can get a fill is at another really good shop in my area that uses the continuous method to fill the tanks. I talked to the other store owner (continuous fill guy) and he said the tanks will be fine to be partial pressure filled if I get a few fills from him because the air they use is all the same( i.e he is putting in a blend of oxygen and air instead of putting in 100% oxygen and then filling the rest of the tank up with OCA). The continiuous guy made a lot of sense to me but I can't get in contact with the guy ive been going to for quite some time which is why im here.

The Questions:
Is it okay to get a nitrox fill from someone who uses the partial pressure method after getting a fill from a blender who uses a continuous method assuming they both have good quality/clean equipment and practice?

Are there any consequences of switching between the two methods?

 

[BRT]

No consequences unless the first shop wants to get paid for another cleaning/viz fee.

 

[JohnnyC]

In theory, unless you're ONLY ever filling them with O2 straight off a supply cylinder and nothing else, anything else you're putting in the tank has the chance to contaminate it. So if you're topping off an O2 fill with air to make some other mix, you're risking contamination, regardless of whether you're going to the first guy or the last guy.

That being said, if both shops are pumping good air, I wouldn't worry about it.

 

[taimen]

No consequences if the CFM fill is done with filters suitable for pp blending.

 

[Zef]

You can purchase an add-on filter that goes between your tank valve and the filling whip of the compressor...many of the tech divers here in Belgium us them when having their O2 cleaned tanks filled with regular air. Using one of these should solve your problem.

300 bar din nitrox personal air filter

-Z

 

[kelemvor]

So to start I had all of m tanks o2 cleaned when I got my nitrox certification because my LDS uses partial pressure blending. I recall him saying(and this could totally be me having a lapse in memory) that if I went anywhere that uses a continuous blend method that I would contaminate my cylinder and then have to get it re-cleaned( he then listed a few sketchy places in my area to get air fills). My problem is that my LDS is shut down right now because the owner has to take care of some personal stuff and the only place I can get a fill is at another really good shop in my area that uses the continuous method to fill the tanks. I talked to the other store owner (continuous fill guy) and he said the tanks will be fine to be partial pressure filled if I get a few fills from him because the air they use is all the same( i.e he is putting in a blend of oxygen and air instead of putting in 100% oxygen and then filling the rest of the tank up with OCA). The continiuous guy made a lot of sense to me but I can't get in contact with the guy ive been going to for quite some time which is why im here.

The Questions:
Is it okay to get a nitrox fill from someone who uses the partial pressure method after getting a fill from a blender who uses a continuous method assuming they both have good quality/clean equipment and practice?

Are there any consequences of switching between the two methods?

Unless he's 02 cleaning the tank before each fill then it's not really o2 clean, reasons already stated above. Most people o2 clean annually if they're getting blended fills (I do). I also get fills from shops that make banked nitrox using a membrane system on occasion.

Personally, I think your "normal shop" guy is just trying to scare you into only using his shop. I wouldn't hesitate to get fills elsewhere. If you want to go back to him later when he re-opens he might require you to pay him for an o2 clean. I don't think it's necessary but it's his fill station and therefore his rules. Alternatively, you could just start using the other shop going forward.

 

[Superlyte27]

Sigh, I get so sick of these scare tactics.

Look, as long as you're getting good clean gas, you can move back and forth from air, nitrox and o2 in the same clean tank. I've been doing it for 20+ years. Our shop has been doing it as one of the first adopters of Nitrox back in the 80's.

If your shop isn't using good clean air, then find a different shop anyway.

 

[Scared Silly]

Once you have O2 clean cylinders what you want to assure is that the gas going into your cylinders has been made with modified grade E air (aka Oxygen compatible air). If not then you can not be assured that you cylinders remain clean.

If the continuous blender is not using a filtration system that produces modified grade E air then your cylinders can no longer be considered to be O2 clean.

You can purchase an add-on filter that goes between your tank valve and the filling whip of the compressor...many of the tech divers here in Belgium us them when having their O2 cleaned tanks filled with regular air. Using one of these should solve your problem.

300 bar din nitrox personal air filter

-Z

Zef, that filter does not help with maintaining O2 cleanness. It helps with suspect air but does not produce modified grade E air.

 

[KentB]

hes scaring you. how does he possibly know if you get a fill between his shops? an O2 clean is only really good for that first initial fill after that its a crap shoot. how can they possibly gaurentee that in the 2 weeks its been since you been back that that was your only dive? your didnt go somewhere and have it filled 1/2 dozen times??? if it was a huge problem you would hear about issues regularly. dont get me wrong I dont want to put anyone in a dangerous position a marked 100% deco bottle sure but a regular HP100 or HP 117/133 or something I seriously think its blown so far outta proportion its crazy

 

[AbnSwmr]

First of all, if the continuos blender guy is convenient, stop wasting time and money with the partial pressure guy.

Second, for PP blending, they use an extra filter to produce OCA (oxygen compatible air) aka hyper pure air. Ask the continuos blender dude if he has a hyper pure filter (or OCA). If it is a tech shop that blends up custom Deco mixes, he will have it.

If you want to keep your tanks "o2 cleaned" make sure any air or Nitrox that is put into them goes through the hyper pure filter (which is down stream of the banks).