Discussion in 'Basic Scuba Discussions' started by jaybombs25, Mar 24, 2007.
do you need seperate regs for nitrox and air, or is it fine to just use the same one?
Have you taken the class yet?
Use the same one.
Most regs are ready for mixes up to EAN40 right out of the box.
Recreational nitrox which will have no more than 40% oxygen can be used with nearly any regulator set.
There 2 issues here...
1. Explosion or fire: Here you are safe at 40% or less.
2. Seal degradation: This is more model and brand sensitive. Nearly all are fine. Check your manual or dealer to be sure. If you are told yours is not OK, call the manufacturer. Some have CYA documentation but if you call and ask they say you are good to go.
This should have been covered in your class.
haven't taken the class yet I was just curious
Its a fair question to ask about before deciding whether to take a class.
Gives you an idea of expense, what has and hasn't got to be changed kit wise so work out if its worth the effort.
There's a LOT of crap out there about nitrox and regs, most of which spread by manufacturers who want to make more money by selling you the same reg with a different sticker on. Most if not all regs work out of the box to 40% which is all you'll ever get to on a basic nitrox course.
The only piece of gear you're likely to own that's not recommended for Nitrox is your tank.
Sometimes Nitrox is pre-mixed & put in your scuba tank.
Sometimes, your tank is partially filled with a given amount of pure oxygen, THEN the nitrogen is added. Pure oxygen is potentially hazardous.
For reasons covered in the Nitrox course, a scuba tank (cylinder) is generally designated for enriched air (for practical purposes what you'd call 'Nitrox'), OR for regular compressed air, but you don't use the same cylinder for both.
But your BCD, first & second stage/regulator & octopus are most likely 'good to go' & can be used with either.
The main advantages with Nitrox involve slower buildup of nitrogen in the body, which lets you:
1.) Spend more time down on deep dives.
2.) Dive more often with shorter surface intervals (a particular issue with tropical vacation shore-diving sites like Bonaire, where you can dive 4 or more times per day if so inclined).
Many people encounter such situations mainly on vacations where they're using rental or 'package deal' tanks anyway, & use their regular tanks with compressed air for local diving, but some people may find it worthwhile to plunk down the cash for a dedicated cylinder for Nitrox use.
You can use the same regs for mixes of up to 40%. This is what the industry has set as the limit. If your systems are going to see more that 40% oxygen, then it is advised to have 'Oxygen cleaned regs and tanks.
Partial presure blending is putting O2 in the tank up to the required level and then adding AIR, not nitrogen. You can use the same tanks for both nitrox and air as long as the tanks do not get to see 40% oxygen or more. I.O.W, if you preblend and fill up to 40%, you can use the same tanks.
Again, 40% is what the industry has set itself as the limit between requiring O2 cleaning and not.
I used to be a lot more worried about this than I am nowadays.
The manual for the regs we use in our family (Aqualung Micras) states that the limit is 23% without preparation.
I had also met, on trips, 2 people that independently had been involved/witnessed incidents and one of them had the burn marks.
When we did the checkout dives for the course I went to the extreme of renting O2 clean regs.
Anyway, a few hundred dives later I never saw anyone taking such precautions and on a few trips where I didn't expect to use Nitrox, but did, and up to 40%, and I just used my normal regs for lack of an option.
So nowadays I don't worry about it, I just open the tank valve very slowly and don't bend over my rig while doing so.
This was my decision and shouldn't be construed as advice for you to do the same.
The best thing is to check for the manufacturer's recommendation. They do tend towards very conservative.
The concern about dedicating a reg to nitrox only is the fear that small trace amounts of oil contamination in the 1st stage can ignite, or can partially burn and put combustion products such as carbon monoxide into the breathing air.
For example, this post lists the recommendations for Atomics regs. Note that Atomics accepts switching back and forth between nitrox up to 40% and standard air for their B2, Z1, and Z2 regulators, but recommends that their titanium 1st stage regulator, the T2, be dedicated to either nitrox service or air service, and that you NOT switch back and forth between regular air and nitrox with the T2.
If you normally use nitrox and are extra paranoid, you can always order up "EAN21" or "hyperfilterd air" for when you want to dive air. In the partial pressure blending method of making nitrox, the shop first puts in some 100% O2, and then tops it off with "hyperfiltered" air. Hyperfiltered air goes through some extra filter stages to further reduce the small trace amounts of compressor oil that is in normal air fills.
The concern is only the first stage since it receives the nitrox at a high preasure. Check with the manufacture on that or in your manual. The 2nd stage doesnot need any special service for nitrox. Your tanks will need to be nitrox cleaned eitherway. That is a $$$ maker for shops,But that is another dicussion
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