39 replies to this topic

[shadragon]

I do not think they made any changes to it, and yep, you get above a certain percentage of oxygen and titanium makes a nice fire. wish we had a camera at the time, but a bunch of people where curious, so they took one and turned it on with the higher oxygen. it did take a little bit, but man that was a hot and bright fire underwater. (and yes the nitrox tank was out of the pool so we could turn it off once the reg went)
thus the reason I am trying to stay away from it. lol.

Question is... Did the guy on his NITROX course pass? haha

Anyone who knows me at all knows I LOVE titanium. Watch, glasses, dive knives... Light weight and strong with little maintenance. I even have a wedding ring picked out for the day when I finally do decide 'she' is the one (Whoever 'she' is...). I have never been disappointed with that metal. However, I would never buy a titanium reg. The cost is exorbitant and whatever weight you save has to go on your weight belt. Nicer to carry through the airport, but that is all.

Now as for the above post I don't think so...

OK, under enough pressure, with an ignition source and 100% O2, titanium will burn. However, so does brass, stainless steel, copper, zinc and others at much lower temps. If a reg has been serviced with an O2 clean kit then chances of ignition are as close to zero as me getting lucky tonight. Yup, that low...

Melting point of pure titanium is 1668 °C (3034 °F). Stainless steel is 1500 °C (2732 °F)

BTW, many aircraft makers use titanium piping and valves for aviation O2 systems.

[Dive_Girl]

But let me also say that the Scubapro Mk2, an extremely basic and cheap unbalanced reg, also gives decent and consistent performance. It's not remotely in the same league as the Titan though.

I can't be certain how long WreckWench has owned her MK2 set, but I was happy to use it for wreck diving in NC when the bungie holding my tank gave and my Apex first stage took a nose dive on the hard deck literally the minute the captain pulled up the buoy of our first dive site - nevermind the 2.5 hour bumpy ride there! Although I now personally dive a MK25, the MK2 was a great regulator!

FYI in regards to the MK25, I have dove mine hard in some of the worst conditions in some of the worst temperature down to 34 degree water on several occassions (including my a snow melt lake dive in 36 degree water I did less than 2 weeks ago) and I have not had an issue with it nor has it free flowed. It has also been my reg of choice for my deep dives (200'+). My second stage is the S555, not the S600 so perhaps that is the difference in my story to those of others. It could also be how our repair techs service them. Settings are made with cold water in mind. I like the S555 so much I actually own 5 (two sets of tech gear and my backup). I have thought about a MK17 for my ponies, but current use a MK25/S555 on those at this time.

Gret thread topic. You have been given some great information and advice by some fantastic members above! Like peterbj7. If anyone knows about regs, it's a dive op who services the rentals!

[KeithT4U]

There is great information here from great divers. One of the local dive shops in Sacramento has an event every June. THey offer classes from the various reps and superb deals on gear. I went to the class offered by the Scubapro rep where he talked about regs and goods and bads of all of them. ON the first stage from his explaination there is little difference in rec diving on balanced vs. unbalanced 1st stages. The main advantages of them coming about in extreme cold and deep diving. However the difference in 2nd stages would be noticable around 60 FSW making a balaced 2nd stage worth the investment for almost all divers. As a note if that rep, forgot his name, might be reading this post and to all in the area of Sacramento next June, attend that class. IT was superb in the information given and extolled the benifits and limits of all manufatures not just Scubapro making it far more informative than it was a sales pitch.

Keith

[davekemph]

"Titanium can catch fire when a fresh, non-oxidized surface gets in contact with liquid oxygen. Such surfaces can appear when the oxidized surface is struck with a hard object, or when a mechanical strain causes the emergence of a crack. This poses the possible limitation for its use in liquid oxygen systems, such as those found in the aerospace industry"

true all things metal will burn when in oxygen, but unlike most metals, titanium will autoignite when enough oxidiser is present. and this aplies to chlorine (which is an oxidizer) also. It is similar to igniting magnesium in air, takes a lot of heat, but it can be done.

so while you are safe below the 40% level in some nitrox mixes, once you get higher you do run the risk of autoignition of the titanium.
and no you do not need to bang the regs around to cause a crack, just the thermal expansion and contraction of normal use will eventually form the cracks in the coating layers and expose the titanium to the oxygen.

so while it might seem like the metal is safe to use for some gas mixes it is not advisable for all of them.

[Dive_Girl]

There is great information here from great divers. One of the local dive shops in Sacramento has an event every June. THey offer classes from the various reps and superb deals on gear. I went to the class offered by the Scubapro rep where he talked about regs and goods and bads of all of them. ON the first stage from his explaination there is little difference in rec diving on balanced vs. unbalanced 1st stages. The main advantages of them coming about in extreme cold and deep diving. However the difference in 2nd stages would be noticable around 60 FSW making a balaced 2nd stage worth the investment for almost all divers. As a note if that rep, forgot his name, might be reading this post and to all in the area of Sacramento next June, attend that class. IT was superb in the information given and extolled the benifits and limits of all manufatures not just Scubapro making it far more informative than it was a sales pitch.

Keith

Would that be Diver Dan's!?? I stopped by there when I was down that way for work last year. How cool!

[shadragon]

"Titanium can catch fire when a fresh, non-oxidized surface gets in contact with liquid oxygen...(snip)"

Exactly correct, but the properties of 100% liquid O2 or LOX are a wee bit different from 100% gaseous O2. The difference is what sends up the space shuttle. In aviation systems liquid O2 is pumped into an evaporator, turned in to gas, warmed up with heaters and THEN dispersed through the titanium lines.

OK, now here is a cool project. Take a gallon of LOX that weighs just over 9 pounds (and only needs to be pressurized to 400 psi), build a converter (which warms it up as well) to turn it into breathing gas and hook a regulator to it. It has an 860:1 expansion ratio which translates to 3255.454 litres of air. That converts to 114.965 cubic feet of O2. Just under a regular 120L tank. Now, you would be limited to diving 33 feet max. to avoid toxicity, but hey, thats the price of science... Now, here is the better solution: Hook that contraption up to a rebreather. According to SDM this gives you 3 - 4 more breaths than an open circuit system so this translates to 345 - 460 cubic feet of usable air on the RB... Oooo baby...!

I know. I know. That pesky -183°C temperature of the LOX will result in a couple of inches of ice around the RB in seconds. Also, many divers tongues will be getting stuck on tanks because of double dog dares, but as I said that is the price of science...

Copyright 2008 Shadragon. All rights reserved. Patent PENDING...

[davekemph]

I am thinking I am going to have to do a mythbusters style experiment in the garage well mayne the backyard, and see at what percentage of oxygen titanium used in regulators starts to cause problems.
and with any luck I will have video for everyone, and will post on a seperate thread.
and yes, I said in regulators, so I will not be using regulators in the process. just the same alloy.
I do not have the budget that mythbusters does.
of course then it is the fun part of finding out what caused the reg in the pool to go.

[peterbj7]

I'm not sure of the detail or I've forgotten it, but I read a report in the DAN magazine a few years ago, certainly in the last 6 years, in which a recreational diver using nitrox and a titanium reg had a fire underwater, and was quite badly injured. The problem was not the first stage but the second, but I'm afraid I don't remember what make the reg was.

The second stage had a predominantly plastic body, with deflector/heat sink vanes in this case made from uncoated titanium. At some point during the dive one of these caught fire, and I suspect the diver wasn't very quick to get the reg out of his mouth. He suffered burns to the inside of his mouth and throat. The mix was undoubtedly no higher than 40% and he won't have been very deep.

You don't need 100% oxygen or any sort of extremes to have this happen to you. As a general rule of thumb stay away from titanium if you're using nitrox.

[uwfan]

Thanks everyone for your posts!! I went out today in my quest for the right reg for me...and I came across a variation from the MK25, MK17, and MK2 that people are talking about...anyone have experience with the MK 11? I'm looking at it with the S555.

Also looking at the Oceanic GT3...anyone have experience with this one? Yea, I guess I'll be a balanced diver...tho I'm sure some might call me unbalanced in other ways!!

[shadragon]

Thanks everyone for your posts!! I went out today in my quest for the right reg for me...and I came across a variation from the MK25, MK17, and MK2 that people are talking about...anyone have experience with the MK 11? I'm looking at it with the S555.

Found these quotes:

"The MK11/S555 regulator system combines the air-balanced valve technology of the S555 with the reliability of a balanced diaphragm first stage. Two easy-to-use regulators come together in a low maintenance and highly enjoyable combination, ideal for temperate waters, providing smooth air delivery at all tank pressures."

"The Scubapro MK11 S555 is new on the market for 2006. Featuring the new MK11 first stage and the redesigned and improved S555 second stage, the MK11 S555 is bristelling with technical improvements. With the MK11 fist stage, the Scubapro engineers have utilised a diaphragm design similar to the MK17AF, making the MK11 first stage ideal for sport divers. The S555 is an balanced, high performance second stage incorporating a redesigned look and technical improvements for 2006. Featuring the VIVA adjustable flow vane, the S555 provides diver adjustment in a simple and easy to use design."

"Few regs offer this kind of breathing performance at such easy-on-the-wallet prices. Both of these breathers earned top honors in this year's reg tests--a Testers' Choice for the MK11/S555 and a Best Buy for the MK11/R395. The compact over-balanced diaphragm MK11 is the engine for both systems. It's a proven performer both on the ANSTI breathing machine and in the water. The main difference between the S555 and the R395 is that the former is pneumatically balanced and the latter is not. This makes the breathing on the S555 less hiccupy in alternate diving positions, but more expensive; the R395 is not as smooth in some dive positions, but cheaper. Take your pick. Either way, you walk away a winner." Link - Best Gear of 2007

Looks like a good warm water reg. Just don't go ice diving in Cozumel and you will be fine...

[uwfan]

Ice diving in Cozumel?...nah, I'll stick to ice skating

One more question...any opinions on balanced versus unbalanced octopus?

Thanks again everyone! You all are awesome!!

[georoc01]

Ice diving in Cozumel?...nah, I'll stick to ice skating

One more question...any opinions on balanced versus unbalanced octopus?

Thanks again everyone! You all are awesome!!

If I am on my octo, the dive is pretty much over, so I am not sure what exactly would be the advantage of spending more for a balanced 2nd stage.

I think the bigger question when it comes to octos is what kind do you like. Something inline on your inflator, a seperate hose or some type of gue configuration with a long hose?

[uwfan]

"Few regs offer this kind of breathing performance at such easy-on-the-wallet prices. Both of these breathers earned top honors in this year's reg tests--a Testers' Choice for the MK11/S555 and a Best Buy for the MK11/R395. The compact over-balanced diaphragm MK11 is the engine for both systems. It's a proven performer both on the ANSTI breathing machine and in the water. The main difference between the S555 and the R395 is that the former is pneumatically balanced and the latter is not. This makes the breathing on the S555 less hiccupy in alternate diving positions, but more expensive; the R395 is not as smooth in some dive positions, but cheaper. Take your pick. Either way, you walk away a winner." Link - Best Gear of 2007

Can anyone explain what is meant by "less hiccupy"? I can see myself (in the future) playing at photography in various positions.

If I am on my octo, the dive is pretty much over, so I am not sure what exactly would be the advantage of spending more for a balanced 2nd stage.

I think the bigger question when it comes to octos is what kind do you like. Something inline on your inflator, a seperate hose or some type of gue configuration with a long hose?

This has generally been my thought as well, just ran across the option and had to ask.

[shadragon]

Can anyone explain what is meant by "less hiccupy"? I can see myself (in the future) playing at photography in various positions.

Some regs can have issues in certain positions. I was once on a rental reg trying to swim straight down into an access hole in the top of a ship bridge and it got a little hard to breath in that position. It was never a critical shortage of air, but was noticeable. In the regular horizontal plane or on ascent I was fine. I assume that is what they are referring too. The MK11/S555 combo looks like a nice reg. I doubt it would have this kind of issue.

As for a balanced Octo. Mine isn't. If I use the octo for me or someone else the dive is over and we are coming up. In an emergency, it works. It delivers air when needed and thats all it is supposed to do. I have only used it twice in 150+ dives and don't see a reason to spend $$$ for balanced. Now my octo (R390 - unbalanced) is hooked to my balanced MK16 on my Pony. The R390 has an adjustable valve which lets me turn it down to stop freeflow. I also use a plug in the mouthpiece to hold it in place on the BC and further stop free flows. I use a 5' yellow hose which is plenty long enough for rec driving and what I do. You can see it in my avatar coming over my right shoulder. Come on the Dolphin trip in September and you can see it for yourself.

There are all sorts of ways to rig alternate air sources. Talk to everyone, read everything you can and choose the way that works for you.