nitrox

[mk706]

Perhaps I have **** luck, but it seems the vast majority of shops I deal, or have dealt with, use partial pressure blending. On that note, have not had tanks with O2 stickers refused to be filled. So, tanks are cleaned each season, and affixed with O2 compatible stickers. All part of the scuba experience.

Consider all the shops worldwide that use partial pressure blending - how often does one blow up? How often do they blow as a result of a contaminated privately owned cylinder? Perhaps one every few seasons? Remember one two seasons ago in South Alabama (aka FL Panhandle) - seem to recall that was a banked tank, not scuba tank. Have not read of a dirty, or contaminated tank causing one of these explosions (not to say it hasn't happened). Most incidents with scuba cylinders seem to be caused by defective tanks or valves. Lots of variables involved, from the fill station, whip, the individual gas blender to the cylinder.

Don't misunderstand, high concentrations of oxygen in tanks can be dangerous. It's hazardous regardless of how it go in the tank.

 

[syntaxerrorsix]

Perhaps I have **** luck, but it seems the vast majority of shops I deal, or have dealt with, use partial pressure blending. On that note, have not had tanks with O2 stickers refused to be filled. So, tanks are cleaned each season, and affixed with O2 compatible stickers. All part of the scuba experience.

Consider all the shops worldwide that use partial pressure blending - how often does one blow up? How often do they blow as a result of a contaminated privately owned cylinder? Perhaps one every few seasons? Remember one two seasons ago in South Alabama (aka FL Panhandle) - seem to recall that was a banked tank, not scuba tank. Have not read of a dirty, or contaminated tank causing one of these explosions (not to say it hasn't happened). Most incidents with scuba cylinders seem to be caused by defective tanks or valves. Lots of variables involved, from the fill station, whip, the individual gas blender to the cylinder.

Don't misunderstand, high concentrations of oxygen in tanks can be dangerous. It's hazardous regardless of how it go in the tank.

That's because it's the least expensive and equipment intensive way to fill. It's also the most accurate way for your standard tank monkey to hit the requested blend.

 

[mk706]

I don't see any issue with partial pressure blending. Just find it odd when other members make statements somehow implying that it's an inferior method. Agree that it's easy, fast & cheap. Would also include safe, if shop & cylinder owners take reasonable precautions.

 

[paddler3d]

Tanks do not have to be Oxygen clean for nitrox < 40%, if a membrane system is used to fill the tanks. You only need O2 cleaning if partial pressure blending is used. If you do have your cylinders O2 cleaned then every airfill whether nitrox or not has to be to the nitrox standard, if you want to maintain them O2 clean. I suspect for recreational diving, if you don't have access to a membrane filling station, don't bother with nitrox. You can recover from the bends, but you can't survive a seizure underwater! The added expense and hassle is not worth it for me. If I go passed a membrane station I get a nitrox fil otherwise I stick to air.

That just doesn't make sense. Getting bent can kill you. You can survive a seizure underwater. What on earth does that have to do with PP filling or banked EAN systems?

To the OP. Get Nitrox certified. Learn about Nitrox. Learn about Nitrox procedures.

I've been certified for Nitrox for years. My tanks are O2 clean. You can learn to do it yourself. It is not rocket science. I just haven't found the need or want to have EAN as my back gas.

Hundreds of dives and maybe a couple dozen with EAN as my back gas.

I feel it pigeon holes me to a MOD, that I may or may not want.

Take the class and learn. At worse you'll become more aware and knowledgeable diver.

 

[JB]

You can survive a seizure underwater.

Forgive me, but in my limited experience I have yet to see anyone diving with a full face mask!

 

[Codiak]

Forgive me, but in my limited experience I have yet to see anyone diving with a full face mask!

You need to dive more!

 

[EastTNDiver]

Tanks do not have to be Oxygen clean for nitrox < 40%, if a membrane system is used to fill the tanks. You only need O2 cleaning if partial pressure blending is used. If you do have your cylinders O2 cleaned then every airfill whether nitrox or not has to be to the nitrox standard, if you want to maintain them O2 clean. I suspect for recreational diving, if you don't have access to a membrane filling station, don't bother with nitrox. You can recover from the bends, but you can't survive a seizure underwater! The added expense and hassle is not worth it for me. If I go passed a membrane station I get a nitrox fil otherwise I stick to air.

While I can see your point on less hassle/expense in using/maintaining your own tanks, I don't understand your other point. How does partial pressure blending contribute more to chance of siezures? You should be analyzing your fills/establishing your MOD regardless of what system is used to do the fill.

 

[boulderjohn]

Surviving a seizure under water demands the efforts of a skilled rescuer, but it has been done. That is why some tech agencies teach the toxing diver rescue as a standard part of the curriculum.

But I still don't see what this has o do with how your nitrox gets into the tank.

 

[paddler3d]

Forgive me, but in my limited experience I have yet to see anyone diving with a full face mask!

Aside from the full face mask.

I have not seen it.

If someone is having an "O2 hit" or CNS, does not mean an automatic death sentence.

It is entirely possible that someone can be rescued from this in SCUBA and survive.

We're talking about EAN and the possibility of oxtox, which is what they teach you in virtually any Nitrox course, is low but, if you ascend, you can alleviate oxto. So in theory you start to witness your buddy begin to seize, you could control their buoyancy and help them to ascend where the pPO2 is t a level where their body can metabolize the excessive O2. They don't drown if their 2nd stage stays in their mouth.

Am I wrong on this one?

 

[boulderjohn]

In the cases I know where people have survived, the key is understanding the stages of the seizure and acting appropriately. During the tonic/clonic phases, it is important to establish and maintain control of the victim and (especially) make sure that the victim has a functioning regulator in the mouth.

It is important to recognize the difference between this and the classic ascent of an unconscious victim, in which case introducing a regulator is not important. In that case, the victim is not breathing and will not be breathing, so there is no point in putting a regulator in the mouth.

During this phase, no effort should be made to surface the diver. The diver is not breathing, and there is a very good chance of introducing a fatal embolism through an ascent.

Once the diver enters the sleep phase of the seizure, it is safe to begin the ascent. The dive will be almost certainly be breathing, so regulator and airway control is critical. If the diver seizes again (which can happen) stop ascending. During the postictal sleep phase, the diver can continue to breathe while unconscious for a very long time, so as long as regulator and airway control are maintained, there is no rush to the surface.

Once again, compare this with the unconscious diver scenario practiced in all Rescue Diver programs and even in some OW programs. An unconscious diver on the bottom is not breathing, and a safe and expedient return to the surface is critical. It is a far more serious case.

Of course, if no rescuer is able to perform a proper rescue at the moment of seizure, then the result will be fatal. However, it is not an automatic death sentence if all goes well.

Once again, though, it is not just violating the maximum depth for the EAN mix that causes this; it is violating it for a period of time, so it is nothing likely to happen in a standard nitrox recreational dive. More importantly, it has nothing to do with the method with which the EAN was mixed.