Regulator questions

[lovles2274]

I'm pretty sure that I've decided to get a Cressi Ellipse Titanium/MC9 regulator set. I know that this regulator is good for up to 40% oxygen right out of the box but, what do I need to do to it so it is compatible for higher concentrations? How expensive is this conversion going to be? (and lastly, any comments about my choice of regulators)

 

[Mr Carcharodon]

Usually regulators with titanium components are not recommended for high fractions of oxygen. That may be less of a concern if only the second stage has titanium. The issue is that titanium can burn leading to an explosion. Probably not very likely but it would make for a bad day if it did. I'd stick with chrome plated brass for high FO2. Also titanium is a poor thermal conductor compared to most metals so it is not an obvious choice for cold water diving. It is corrosion resistant, light and strong however.

 

[Jocull]

Usually regulators with titanium components are not recommended for high fractions of oxygen. That may be less of a concern if only the second stage has titanium. The issue is that titanium can burn leading to an explosion. Probably not very likely but it would make for a bad day if it did. I'd stick with chrome plated brass for high FO2. Also titanium is a poor thermal conductor compared to most metals so it is not an obvious choice for cold water diving. It is corrosion resistant, light and strong however.

Fortunately he will be under water

 

[Damselfish]

Fortunately he will be under water

not when he turns the tank on...

 

[DevonDiver]

Fortunately he will be under water

...with high O2 in contact with combustable material...at sufficient temperature for ignition.

Underwater fire... scary huh? Especially when it's connected to an explosively high pressure tank strapped to your back...and you're mouth is wrapped around a hose connected to it....

Think it's impossible? Then how do commerial divers weld metal underwater? Oh yes... they use high O2....

A fire needs three elements: Oxygen. Fuel. Temperature (ignition).

High O2 mix. Oxygen. tick!
Ti or contaminated (non-O2 clean) Regulator. Fuel. tick!
Gas friction through the regulator 1st stage. Temperature. tick!

Ka-boom!

Water normally smothers a fire, by reducing the oxygen that can reach the material it prevents combustion. If you have a direct, high%, oxygen supply to the fuel...then you still have fire, even if underwater.

With very high %O2, the need for high temperature and combustability of the fuel is decreased. A little hydro-carbon contamination inside the reg 1st stage is sufficient fuel. The temperature caused by gas friction through the reg can be sufficient temperature. The high O2 can cause ignition of the initial contaminant material. That, in turns,super-heats (due to the O2) and ignites other combustable materials... rubber hoses, o-rings (even the O2 suitable ones have a combustion point). Those create further heat. That leads to further combustion in 'non-flammable' (pretty much anything is actually flammable given enough O2 and temperature) items such as metals...

For the OP: You won't be using >40% until you start technical diving. That means Advanced Nitrox and Deco procedures. >40% is only used for accelerated decompression. That means you would have a dedicated O2 clean regulator on a stage deco cylinder containing the high O2% mix. You'll be spending a lot of money to train and equip yourself for that sort of diving.

The best bet for a stage deco regulator is something basic that can be easily O2 cleaned. Apeks '50s are perfect. I guarantee that you could pick one of these up on Ebay/Craig's List for a lot cheaper than converting your Ti regulator into a deco regulator.... if you can even get the conversion done...

 

[lovles2274]

How about this.....The Cressi Ellipse Titanium only uses titanium on the external (not coming in contact with the compressed gas) faceplate. Internal components are more traditional brass. I realize that as a new diver I won't need the higher concentrations of O2 for a while but, why spend $400-$500 for something that won't be usable later. I plan on continuing to advance my certifications so I will need another regulator for my desaturation bottle. I was thinking that I could possibly use this one and purchase a more advanced regulator for my primary (later when needed).

 

[DevonDiver]

In reality, the cost of a cheap deco reg from Ebay is just a p1ss in the ocean when it comes to equipping yourself for technical/decompression diving.

Rather than stripping the regulator down for use as a deco reg, chances are you'd keep it preserved for when you simply single-tank dive...

 

[tbone1004]

agreed with Andy. You can get Apeks 50's for not a whole lot of money... The ATX50's are GREAT regulators, and are being cloned by a LOT of other dive manufacturers. HOG being the big thing now. Never dove with the Cressi's but if you're interested in getting into tech later, save yourself the money and buy the right stuff now.
Andy said you can keep the cressi for a single tank rig, which a lot of us do, but a lot of the time for me, its easier to bring my doubles regs and switch the primary over than have a whole separate setup for single tanks.

 

[scubadiver888]

How about this.....The Cressi Ellipse Titanium only uses titanium on the external (not coming in contact with the compressed gas) faceplate. Internal components are more traditional brass. I realize that as a new diver I won't need the higher concentrations of O2 for a while but, why spend $400-$500 for something that won't be usable later. I plan on continuing to advance my certifications so I will need another regulator for my desaturation bottle. I was thinking that I could possibly use this one and purchase a more advanced regulator for my primary (later when needed).

Looking at the specs for this set up, it is VERY light but a lot of the other stuff I read sounds like a load of marketing gobbledy-gook. I believe in the K.I.S.S. principle: Keep It Simple Sir. The more complicated something is, the more risk of failure. Also, the harder and more expensive it is to service. If the shop you bring it to doesn't service these things on a regular basis, the greater the risk they will not service it properly.

The initial purchases matter for the first year. Every subsequent year is based on how easy and well the thing can be serviced. If you don't have someone who can service it or the parts are expensive then you could end up spending a lot more on it in the long run.

Personally, a few extra grams isn't going to make a huge amount of different. A good set of hoses will make a much bigger impact on jaw fatigue.

If you want to plan ahead for getting into say technical diving, you'll need two regulator sets for diving doubles. These regulators have to be simple, durable, robust and operate well at any depth down to say 65m. You could purchase a regulator which will handle these requirements and use it later as one of the two sets. The other set of regulators you would need will be for say a 50% oxygen bottle during decompression/safety stop. So you need something that can be oxygen clean.

The most important thing is that everything needs to be reliable. The less failure points the better. As a recreational diver you always have the option of a Controlled Emergency Swimming Ascent (CESA). As a technical diver, you have decompression obligations and therefore cannot do CESA. You must remain at depth until you have sufficiently off-gassed.

The other option is to do what I did. Buy something inexpensive but reliable for recreational diving. When it comes time to do technical diving, just buy everything new and sell my current regulator to someone or keep it when I'm teaching recreational classes in the pool.

When you look at the costs for technical diving, a couple of hundred dollars for a single regulator is nothing.

 

[lovles2274]

Ok...final update. I ended up getting a Cressi Ellipse Balanced / MC-9 SC.....I'm very excited about this regulator. LDS has ordered a Cressi Octopus for me. I've come to determine that divers (like other sports enthusiasts) are very brand loyal. I've read many reviews and blogs about Cressi and I'm very comfortable with my decision to go with Cressi. I can't wait to get in the water. My wife and I are newly certified and its been too cold to dive (I live in Florida and I'm not prepared to go diving in 45 degree weather) and I'm losing my mind. I'm like a kid with a new toy that I can't play with. In less than 2 weeks we have our Advanced Open Water and Nitrox class. I'm not really sure this post fits but, I'm just excited about diving and wanted to share. Happy New Year.